Patent Publication Number: US-2023135936-A1

Title: Interfaces to manage inter-region connectivity for direct network peerings

Description:
This application is a continuation of U.S. patent application Ser. No. 16/723,667, filed Dec. 20, 2019, which is a continuation of U.S. application Ser. No. 16/024,549, filed Jun. 29, 2018, now U.S. Pat. No. 10,516,603, which is a continuation of U.S. patent application Ser. No. 13/335,465, filed Dec. 22, 2011, now U.S. Pat. No. 10,015,083, which are hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     Many companies and other organizations operate computer networks that interconnect numerous computing systems to support their operations and the services they provide to their end customers distributed worldwide. For example, data centers housing significant numbers of interconnected computing systems have become commonplace, such as private data centers that are operated by and on behalf of a single organization, and public data centers that are operated by entities as businesses to provide computing resources to customers. In many cases providers set up large networks that may logically span several regions or even countries, and may include numerous data centers with varying levels of services and facilities available, utilized together to provide a unified set of services to their end customers. 
     In some data centers that have been set up to provide computing and/or storage facilities to remote clients, the set of computational resources at the data center may be dynamically divided into resource pools, with each pool being made available for exclusive use by a given client for designated periods of time. There are a number of alternatives available for how the consumers of these facilities establish network connectivity to the resource pools that have been designated for their use. The customer requests may originate from a wide variety of devices—desktop personal computers, laptops, client-office servers, tablets, smart phones and the like. These devices may use either long-lasting network links (e.g., using a client office network with a T1 connection) to communicate with their proximate private network and/or the public Internet, or they may have transient connectivity (e.g., in the case where the customer uses a mobile smart phone). The proximate networks to which the customer devices are directly connected may in turn route request traffic to the provider network&#39;s data centers over a wide variety of paths. Such paths in many cases may have somewhat unpredictable performance, reliability and security characteristics. 
     For some casual types of service requests, such as a request from a customer to read a recent news article from a web-based news provider, a reasonable variation in responsiveness and an occasional dropped connection may be acceptable. However, for many business-related data transmissions, such as stock quote services and stock purchase order services provided by online stock traders, or for high-bandwidth software package deployments originating at a software development center, more stringent performance, reliability and security needs may exist. In such environments, a customer of the provider network may need a greater level of network isolation and control than is generally available over the public Internet. For example, the customer may wish to establish, if possible, dedicated physical network links between the customer&#39;s own network and the provider network, such that the only traffic transmitted over those links is traffic generated on behalf of the customer and in accordance with policies established by the customer. Furthermore, to meet quickly changing business needs, customers may want the ability to enable and disable such dedicated links dynamically and with a minimum of effort and delay. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    illustrates an example system, according to at least some embodiments. 
         FIG.  2    provides a high level overview of steps that may be taken with the help of services provided by a connectivity coordinator to establish dedicated connectivity between a client network and a resource collection, according to at least some embodiments. 
         FIG.  3    illustrates an example of constituent elements of a request for dedicated connectivity from a client, according to at least some embodiments. 
         FIG.  4    illustrates an example of constituent elements of a response to a request for dedicated connectivity, according to at least some embodiments. 
         FIG.  5    illustrates an example of constituent elements of a request for a logically-isolated network path, according to at least some embodiments. 
         FIG.  6    illustrates an example of contents of a confirmation message indicating that requested connectivity has been established, according to at least some embodiments. 
         FIG.  7    illustrates an example of two logically-isolated network paths sharing a physical link established using an interface provided by a connectivity coordinator, according to at least some embodiments. 
         FIG.  8    is an illustration of a portion of an exemplary web-based interface that may be provided by connectivity coordinator, according to at least some embodiments. 
         FIG.  9    is a flowchart of a method for providing connectivity-related services, according to at least some embodiments. 
         FIG.  10    is a flowchart of a method for providing connectivity-related services including guidance on configuring a client network device, according to at least some embodiments. 
         FIG.  11    illustrates an example of a system including a provider network to which connectivity may be provided from client networks via “last-mile” connectivity providers, according to at least some embodiments. 
         FIG.  12    illustrates an example of constituent elements of a request for dedicated connectivity through a connectivity provider, according to at least some embodiments. 
         FIG.  13    illustrates an example of constituent elements of a response to a dedicated connectivity request that includes information on available connectivity providers, according to at least some embodiments. 
         FIG.  14    illustrates an example communication from a client identifying a selected connectivity provider, according to at least some embodiments. 
         FIG.  15    illustrates example communications from a connectivity coordinator to a connectivity provider and a client after the client has selected the connectivity provider, according to one embodiment. 
         FIG.  16    is an illustration of a portion of an exemplary web-based interface that may be provided for initiating connectivity provider selection, according to some embodiments. 
         FIG.  17    is a flowchart of a method for enabling clients to select connectivity providers, according to at least some embodiments. 
         FIG.  18    is a flowchart of a method for providing dynamic connectivity-related services, according to at least some embodiments. 
         FIG.  19    is a flowchart of a method comprising responding dynamically to changing traffic levels, according to at least some embodiments. 
         FIG.  20    illustrates an example of a system including a provider network within which a client has established a service potentially accessible to other clients via dedicated physical links, according to at least some embodiments. 
         FIG.  21    illustrates examples of constituent elements of a service advertisement request that may be sent to a connectivity coordinator by a client, according to at least some embodiments. 
         FIG.  22    illustrates an example of constituent elements of a service discovery request that may be sent to a connectivity coordinator by a client, according to at least some embodiments. 
         FIG.  23    illustrates an example of constituent elements of a service availability notification that may be sent by a connectivity coordinator to a client, according to at least some embodiments. 
         FIG.  24    illustrates an example of constituent elements of a service selection notification that may be sent by a client to a connectivity coordinator, according to at least some embodiments. 
         FIG.  25    illustrates an example of constituent elements of a subscription verification request that may be sent by a connectivity coordinator to a client, according to at least some embodiments. 
         FIG.  26    is an illustration of a portion of an exemplary web-based interface that may be provided for marketplace operations such as service advertisements, subscriptions and the like, according to some embodiments. 
         FIG.  27    is a flowchart of a method for enabling marketplace operations to which access is configurable via direct physical links, according to at least some embodiments. 
         FIG.  28    is a flowchart of a method comprising using subscription slots to manage incoming subscription requests, according to at least some embodiments. 
         FIG.  29    illustrates an example of a system with a provider network comprising a plurality of geographical zones, according to at least some embodiments. 
         FIG.  30    illustrates examples of constituent elements of a remote resource collection enumeration request that may be sent to a connectivity coordinator by a client, according to at least some embodiments. 
         FIG.  31    illustrates examples of constituent elements of a remote resource collection enumeration response that may be sent by a connectivity coordinator to a client, according to at least some embodiments. 
         FIG.  32    illustrates examples of constituent elements of a remote logical connection request that may be sent by a client to a connectivity coordinator, according to at least some embodiments. 
         FIG.  33    illustrates examples of constituent elements of a metadata transmission request that may be sent by a connectivity coordinator to a client, according to at least some embodiments. 
         FIG.  34    is an illustration of a portion of an exemplary web-based interface that may be provided to allow a client to request the establishment of a logically-isolated path to a remote resource collection, according to some embodiments. 
         FIG.  35    is a flowchart of a method for providing connectivity services across geographical zones of a provider network, according to at least some embodiments. 
         FIG.  36    is a block diagram illustrating an example computer system that may be used in some embodiments. 
     
    
    
     While embodiments are described herein by way of example for several embodiments and illustrative drawings, those skilled in the art will recognize that embodiments are not limited to the embodiments or drawings described. It should be understood, that the drawings and detailed description thereto are not intended to limit embodiments to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope as defined by the appended claims. The headings used herein are for organizational purposes only and are not meant to be used to limit the scope of the description or the claims. As used throughout this application, the word “may” is used in a permissive sense (i.e., meaning having the potential to), rather than the mandatory sense (i.e., meaning must). Similarly, the words “include,” “including,” and “includes” mean including, but not limited to. 
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Various embodiments of methods and apparatus for using interfaces such as application programming interfaces (APIs) to manage dedicated network connectivity between customer networks and provider networks are described. Networks set up by an entity such as a company or a public sector organization to provide one or more services accessible via the Internet (such as various types of cloud-based computing or storage) to a distributed set of clients may be termed provider networks in this document. Such a provider network may include numerous data centers hosting various resource pools, such as collections of computer servers, storage devices, networking equipment and the like, needed to implement and distribute the services offered by the provider. 
     In order to extend the geographical areas over which its services can be accessed with desired levels of performance, reliability and security, an operator of a provider network may establish dedicated private network paths between its data centers and one or more routers that are physically located at a facility remote from the data centers. The facilities at which these routers are housed are termed “router co-location facilities” in this document, as they may sometimes house routers and other network equipment owned and/or managed by business entities other than the provider network&#39;s operator, such as by independent network service providers or by the clients themselves. Routers owned or managed by, or on behalf of, the provider network operator at the router co-location facilities are called “endpoint” routers in this document, as they may represent the furthest points to which the provider network&#39;s control or ownership of network equipment extends. For example, only traffic that has passed through a device owned or managed by the provider network operator, and therefore complies with policies set by the provider network operator, may be allowed on the private paths between the endpoint routers and other components of the provider network. In some embodiments one or more other routers at the router co-location facilities may be part of a client network—i.e., such routers may owned and/or managed by or on behalf of the clients, or the other routers may have private connectivity to the systems at which clients of the provider network generate service requests for the provider network. These other routers are termed “client-side” routers in this document. 
     In order to facilitate the management of network connectivity between the client networks and the provider network, in some embodiments a connectivity coordinator responsible for implementing one or more programmatic interfaces through which connectivity-related requests from clients are handled may be set up. A variety of different kinds of connectivity-related requests, such as requests to discover the types of connectivity options that may be accessible, requests to select a particular connectivity option or service, requests to set up or dismantle a physical link, and the like may be made available through the interface in different implementations. The interface may be exposed to the client in many different ways in various embodiments: for example, as an API, through a graphical user interface, a web page or web site, or even as a collection of commands that can be issued from a computer system&#39;s command-line prompt. 
     In one embodiment, one or more collections or pools of resources at a data center may be allocated for use by a particular client, i.e., to implement functionality needed to satisfy services requested from devices of the client network. In such an embodiment, a connectivity coordinator may be operable to receive a request to establish dedicated connectivity from a client to one or more of the resource pools. The connectivity request may be generated or formatted to conform to the interface implemented by the connectivity coordinator—for example, it may be received via a web-based form submission in a case where the interface is presented to the client as a set of web pages. In response to the request for dedicated connectivity, the connectivity coordinator may select a particular endpoint router from among the set of endpoint routers of the provider network as the target router from which dedicated connectivity is to be provided to the requesting client. For example, the target router may be selected from the available endpoint routers at a router co-location facility geographically closest to the client&#39;s premises, at which the client has access to an existing client-side router. In some implementations the interface may allow the client to specify various details in the request that may help the connectivity coordinator choose an appropriate target endpoint router, such as one or more names and/or addresses of router co-location facilities, a desired bandwidth, desired price ranges, and the like. 
     Having selected the target endpoint router, the connectivity coordinator may generate configuration instructions for one or more physical network links to be established to provide the desired dedicated connectivity, and transmit the instructions back to the client in reply to the client&#39;s request. The reply may also be generated to conform to the interface implemented by the connectivity provider: e.g., in a case where a web page with a form was used for the client request, the configuration instructions may also be specified as one or more web pages, or as links to documents accessible from the web site. The configuration instructions may, for example, identify a physical location of the endpoint router, a physical port of the target endpoint router, the rack in which the target router is housed, the kind of connector required for the physical link, and so on. After the client sets up the physical network link in accordance with the instructions, the connectivity provider in some embodiments may verify that the link has been set up correctly and send a confirmation message to the client indicating that the requested dedicated connectivity has been established. 
     Example System Environment 
       FIG.  1    illustrates an example system environment, according to at least some embodiments. The system  100  may include a provider network  105  with one or more data centers  110  maintained to provide services to clients, such as cloud computing services or cloud storage services. The data centers  110  in turn may include resource collections such as  120 A and  120 B. Each resource collection  120  may include a set of resources (for example, computer servers, storage devices, network devices, etc.) such as resources  112 A in resource collection  120 A and resources  112 B in resource collection  120 B. The system  100  may also include a connectivity coordinator  114  configured to provide a connectivity service to the clients, a connectivity database  115 , and a plurality of endpoint routers such as endpoint routers  132 A and  132 B in some embodiments. The endpoint routers  132  may be linked to the resource collections  120  via private network paths such as paths  170 A,  170 B,  170 C and  170 D. Direct use of a private network path  170 , such as  170 A- 170 D, may be limited to devices and servers of the provider network, i.e., a network packet may only be physically transmitted upon a link of the private network path from a device owned or managed by the owner of the provider network. The term “path” as used herein, broadly refers to the set of links and devices traversed by a network message or packet between a source device and a destination device. The set of links of a given path may, in some cases, comprise a single wire, as when the source and destination may be linked directly by a physical cable. In other cases the path may include multiple wired and/or wireless links and several intermediary devices such as switches, gateways, routers and the like. Paths may comprise unidirectional and/or bidirectional physical links. 
     In the illustrated embodiment, two example client networks  162 A and  162 B representing respective clients of the provider network  105  are shown. Each client network comprises a plurality of client devices  148  (e.g.,  148 A and  148 B) from which requests that are ultimately serviced at resource collections  120  may be generated. Such client devices  148  may include a variety of systems such as desktop or racked computer systems, laptops, notebooks, tablets, smart phones and the like. Some client devices  148  may be housed at client data office premises, client data centers, or client home premises in various embodiments, and others may be mobile devices with no fixed physical location. In the illustrated environment, the client devices  148  of a particular client have access to a client-side router—e.g., client devices  148 A of client network  162 A are connected to client-side router  142 A via path  160 A, and client devices  148 B of client network  160 B are connected to client-side router  142 B via path  160 B. 
     Client-side router  142 A in the example shown in  FIG.  1    is housed at a router co-location facility  150 A, where endpoint router  132 A is also present, and client-side router  142 B is housed at a router co-location facility  150 B where endpoint router  132 B is located. In general, a number of different types of paths to various components of data center  110 , such as connectivity coordinator  114  and resource collections  120 , may be available from client networks  162 A in various embodiments. For example, a path  175  that does not include endpoint router  132 A is shown in  FIG.  1    between client devices  148 A of client network  162 A and connectivity provider  114 ; such a path  175  may include various routers, gateways and devices of the public Internet, for example, which may or may not provide desired levels of performance, availability, reliability or other service characteristics required for some of the services provided by the provider network  105 . Other paths similar to  175 , but not illustrated in  FIG.  1   , may also be available to the resource collections  120  from client devices  148 A and/or  148 B. 
     The connectivity service provided by connectivity coordinator  114  may include a number of techniques implemented to help clients of the provider network establish and manage dedicated network paths from the client networks  162  to the resource collections  120  in various embodiments. For example, a cross-network connection  191  including a physical link or cable between client-side router  142 B and endpoint router  132 B may have been established with the help of some of the features of the connectivity service provided by connectivity coordinator  114 . The term cross-network connection, as used herein, refers to a physical network connection set up between two autonomous networks. For example, within the Internet, an autonomous network may be identified by a unique Autonomous System (AS) identifier—a collection of connected Internet Protocol (IP) routing prefixes under the control of one or more network operators that presents a common, clearly defined routing policy to the Internet. In the illustrated embodiment, the connectivity coordinator  114  may be operable to implement an interface defining various connectivity operations available to clients, including establishment of cross-network connections such as connection  191 , and establishment of logically isolated connections or paths using such cross-network links. The interface may be implemented using a variety of approaches: e.g., as an application programming interface (API), a web-based interface, other graphical user interfaces, or command-line interfaces, in different embodiments. Connectivity coordinator  114  may also make the interface known to clients using various mechanisms—e.g., a notification detailing the interface may be published on one or more corporate web sites in one embodiment. Connectivity coordinator  114  may itself be resident outside provider network  105  in some embodiments, and in other embodiments it may be incorporated within the provider network  105 . 
     Using the interface implemented by connectivity coordinator  114 , a client may generate a request for dedicated connectivity. The client may, by making such a request, wish to indicate that a physical network link (similar to cross-network connection  191  shown in  FIG.  1   ) be established exclusively for a client network  162 A to communicate with one or more resource pools  120 , for any of a number of reasons such as better performance, higher reliability, enhanced security, or lower or more predictable cost. The exclusivity requirement may indicate that only traffic to or from a specified set or sets of network addresses in the client&#39;s network should be allowed over the requested dedicated physical network link. The set or sets of physical addresses may be identified and/or modified by the client after the physical link has been set up in some implementations, i.e., they may not have to be specified prior to the initial establishment of the physical link. The request may provide any combination of a number of different details that may be of use to connectivity provider  114  in various embodiments—for example, the physical location of one or more client-side routers that could be used, a desired bandwidth and, or other service requirements. In some implementations specific service requirements may be provided in subsequent requests after the initial request to establish dedicated physical connectivity has been sent. 
     In response to receiving such a request, connectivity coordinator  114  may select a particular endpoint router  132  that may be appropriate to meet the requirements of the client. For example, the endpoint router that is physically closest to one or more client premises where the majority of client requests may be expected to originate may be chosen in one implementation. Having selected the target endpoint router to provide the dedicated connectivity, the connectivity coordinator  114  may generate a reply or notification comprising configuration instructions for a physical network link to be established to the target endpoint router  132  to provide at least a portion of the desired dedicated connectivity. The instructions may include a variety of elements in various embodiments, including for example a port number, rack identifier and the like to identify the target endpoint router. The instructions may also be generated in accordance with the interface—for example, as the contents of a web page in an implementation where the request was received as a web-based form submission. In some cases multiple responses may be sent by the connectivity coordinator—for example, a combination of one or more web responses to the requester, and one or more email messages, some of which may be sent to entities other than the client, such as the operator of the router co-location facility  150 . The response or responses from the connectivity coordinator  114  may be used to set up the physical link needed. The time taken to establish the physical link may vary widely, depending on the responsiveness of the client, the responsiveness of the operator of the router co-location facility  150 , and various procedures that may have to be completed for security, authorization and the like. After the physical network link has been set up, the connectivity coordinator  114  may in some embodiments transmit a confirmation message to the client indicating that the desired dedicated connectivity has been established. Various connectivity related information, including for example data identifying details of physical links such as cross-network connection  191 , data identifying the clients for which such links have been established, the dates or times of establishment of dedicated connectivity, and the like, may be stored in connectivity database  115  in some embodiments. 
     In addition to the network paths illustrated in  FIG.  1   , in many environments there may be several other alternative network paths available between the client networks  162  and various components of the system  100 . For example, some connectivity requests may be transmitted to the connectivity provider  114  over a path that includes public or shared links, and various services provided at resource collections  120  may be accessed over public or shared links as well. In some cases the alternative paths may serve as backups in case connectivity over the desired dedicated paths is interrupted. 
     Physical and Logical Connectivity Establishment 
       FIG.  2    provides a high level overview of steps that may be taken with the help of services provided by connectivity coordinator  114  in one embodiment to establish dedicated connectivity between a client network  162  and a resource collection  120 . As shown in the entry labeled  201  in  FIG.  2   , the connectivity coordinator  114  may implement an interface defining a set of connectivity-related operations available to clients of the provider network  105 , to other entities (such as one or more administrative servers, measurement agents, billing agents and the like) and/or other parties. The set of available operations may include, for example, operations to create, query, retrieve, update or delete connectivity records or objects in some implementations. The available operations may be exposed via application programming interfaces (APIs) in any of a variety of standard specifications or programming languages, such as Web Services Description Language (WSDL), XML, Java, C, C++, Python, Perl, or derivatives thereof, in some environments, where clients may interact with the connectivity provider programmatically by issuing method calls, function calls and the like. In other environments, in addition to or instead of providing a public API using which clients may write code, the connectivity coordinator may provide a more user-friendly interface such as a collection of Web pages. In one implementation, the connectivity coordinator may for example publish a set of documents (similar to Javadocs in a case where Java or a Java-like programming language is used) that provide an exhaustive list of APIs, and may expose a frequently used subset of connectivity-related operations via a Web page or pages. In such an environment a client may opt to use the Web pages for common operations, and may resort to programs that invoke the API calls for more complex operations or for operations for which a web interface is not provided by connectivity coordinator  114 . A particular web-based interaction with the client may result in an invocation of one or more of the APIs internally at the connectivity coordinator  114  in some such embodiments. Other types of interfaces, such as command-line tools, independently installable graphical user interfaces (GUIs) (i.e., GUIs that do not rely on Web pages and HTTP-based interactions), thick clients, electronic mail, or messaging protocols, may be used in isolation or in combination to implement the services provided by connectivity coordinator  114  in various embodiments. In some cases the interface may consist of multiple layers, where one layer of interface may invoke another, and one or more of the layers may be exposed for direct client interactions. 
     In one embodiment, the connectivity coordinator may provide a “Getting Started Guide” or some other similar documentation that may provide examples of how the interface may be used. The following list, with entries labeled API-1 through API-18, is a set of API call invocation examples that may be provided in such documentation for a subset of connectivity services provided by connectivity coordinator  114 . 
     [API-1] CustomerId customerId=createNewCustomer(CustomerInfo customerInfo);
 
The createNewCustomer API may be used to create a customer account at the connectivity provider. It may take customer information (e.g., name, address, payment-related details) as input, and return a customer identifier.
 
[API-2] ConnectionRequestId requestId=requestDirectConnection(CustomerId customerId, ConnectionSpecification connectionSpecification);
 
The requestDirectConnection API may be used to by a customer to send a request for dedicated connectivity, with various details of the properties of the desired connectivity encapsulated in a ConnectionSpecification object.
 
[API-3] RequestStatus requestStatus=getConnectionRequestStatus(CustomerID customerId, RequestId requestId);
 
A customer may use the getConnectionRequestStatus API to query the current status of a connection request—for example, the connectivity provider may indicate in the returned RequestStatus object that the current state is “in-progress”, “completed” or “rejected”.
 
[API-4] ConnectionId connectionId=getConnectionId(CustomerID customerId, RequestId requestId);
 
If a Connection Object is created successfully by the connectivity coordinator (and for example stored in connectivity database  115 ), a client may use the getConnectionId API to obtain an identifier for that connection object.
 
[API-5] ConnectionInfo connectionInfo=getConnectionInfo(ConnectionId connectionId);
 
The getConnectionInfo API may be used to obtain the properties of the connection object, including such properties as the physical location of a router, a port number, traffic usage metrics, etc.
 
[API-6] PhysicalConnectionInfo physicalInfo=getPhysicalConnectionInfo(ConnectionInfo connectionInfo);
 
The getPhysicalConnectionInfo API may be used to extract the location-specific properties of the connection object from the ConnectionInfo object.
 
[API-7] AuthInfo authInfo=getAuthInfo(PhysicalConnectionInfo(physicalConnectionInfo);
 
The getAuthInfo API may be used to extract authorization-related information for the connection—e.g., a document allowing a technician to enter the premises where an endpoint router  132  is housed, and make a physical network link to an endpoint router.
 
[API-8] RequestStatus modificationStatus=modifyConnection(ConnectionId connectionId, ModificationInfo modificationInfo);
 
The modifyConnection API may be used to request changes to an existing Connection—e.g., to request more bandwidth.
 
[API-9] RequestStatus disableStatus=disableConnection(ConnectionId connectionId);
 
The disableConnection API may be used to request that an existing connection be disabled, i.e., that no traffic be allowed to flow through the physical link previously set up for that connection.
 
[API-10] RequestStatus enableStatus=enableConnection(ConnectionId connectionId);
 
The enableConnection API may be used to request that an existing (e.g., currently disabled) connection be enabled.
 
[API-11] RequestStatus deleteStatus=deleteConnection(ConnectionId connectionId);
 
The deleteConnection API may be used to request that a connection be removed permanently.
 
[API-12] LogicalRequestId logicalRequestId=set UpLogicalConnection(ConnectionId connectionId, LogicalConnectionParameters lcParameters);
 
The setUpLogicalConnection API may be used to request that a logically isolated network path be set up using a previously established physical connection and a set of logical connection properties encapsulated in a LogicalConnectionParameters object.
 
[API-13] LogicalConnectionId logicalConnectionId=getLogicalConnectionId(LogicalRequestId logicalRequestId);
 
A client may use the getLogicalConnectionId API to obtain an identifier for a particular logical connection.
 
[API-14] LogicalConnectionInfo logicalConnectionInfo=getLogicalConnectionInfo(LogicalConnectionId logicalConnectionId);
 
The getLogicalConnectionInfo API may be used to obtain the properties of the logical connection, including such properties as the VLAN tag being used for the logical connection, and/or other routing-related information associated with the logical connection.
 
[API-15] LogicalConnectionRequestStatus modificationStatus=modifyLogicalConnection(LogicalConnectionId logicalConnectionId, LogicalConnectionModificationInfo modificationInfo);
 
The modifyLogicalConnection API may be used to request changes to an existing logical connection—e.g., to modify the set of network prefixes associated with it.
 
[API-16] LogicalConnectionRequestStatus disableLogicalConnectionStatus=disableLogicalConnection(LogicalConnectionId connectionId);
 
The disableLogicalConnection API may be used to request that an existing logical connection be disabled, i.e., that no traffic be allowed to flow through the logically-isolated path associated with the logical connection.
 
[API-17] LogicalConnectionRequestStatus enableLogicalConnectionStatus=enableLogicalConnection(LogicalConnectionId connectionId);
 
The enableLogicalConnection API may be used to request that an existing (e.g., currently disabled) logical connection be enabled.
 
[API-18] LogicalConnectionRequestStatus deleteLogicalConnectionStatus=deleteLogicalConnection(LogicalConnectionId connectionId);
 
The deleteLogicalConnection API may be used to request that a logical connection be removed permanently.
 
     Turning again to  FIG.  2   , the next high-level step illustrated at  206  is the establishment of a client account, which may be used for example for billing purposes. In some embodiments the interface provided by connectivity coordinator  114  may be used (such as via an invocation of a createNewCustomer API or via a web interface that in turn invokes a similar API) to set up the customer account. In other embodiments the connectivity coordinator  114  may not be involved in account creation directly, and some other mechanism (such as interactions with an account manager component not shown in  FIG.  1   ) may be used to set up customer accounts. 
     A customer that has an account set up may use the interface implemented by connectivity coordinator  114  to first establish a physical link for the desired dedicated connectivity (entry  211  in  FIG.  2   ), and then establish one or more logically-isolated network paths that use that physical link (entry  221 ). Finally, the functionality of the dedicated connectivity may be verified or validated (entry  231 ), e.g., in some embodiments the client and/or the connectivity coordinator  114  may perform one or more verification operations and confirm that the client&#39;s request has been satisfactorily implemented. Each of the high-level steps illustrated in entries  211 ,  221  and  231  of  FIG.  2    may involve several interactions and/or operations at the client end and at connectivity provider  114 , and further details of each high-level step are provided below. 
     Example Requests and Responses for Connectivity Establishment 
       FIG.  3    illustrates exemplary elements of a request  351  for dedicated connectivity from a client, according to one embodiment. As shown, the request, which may be generated at a client device  148  and may be formatted in accordance with the interface provided for connectivity-related services by connectivity coordinator  114 , comprises location information  360 , bandwidth requirement  361 , availability requirement  363 , multi-path requirement  365 , client network equipment information  367 , and additional specifications  368 . Not all these elements may be included in a connectivity request; any combination or subset of these and other elements may be included in the requests in various embodiments. In implementations where an API similar to the requestDirectConnection API described above is used, some or all of the request elements may be provided as fields of a ConnectionSpecification object or its equivalent. 
     The location information  360  may include details of a physical location at which the dedicated connectivity is desired: for example a street address where a client-side router  142  currently exists or where such a client-side router may need to be set up, e.g., with the help of a third-party network service provider. In some cases the client may simply list one or more cities or even states where portions of the client network  162  are located and request the connectivity coordinator  114  to provide a set of possible sites where a physical connection could be set up to serve the client network. 
     In some implementations the client may specify a desired bandwidth for the dedicated connectivity via bandwidth requirement  361 . The interface provided to the client by connectivity provider may, for example, allow the client to choose among a discrete set of bandwidth choices such as 500 Megabits/second, 1 Gigabit/second or 10 Gigabits/second, where the choices may be derived from the details of the specific networking hardware available for establishing a physical link to an endpoint router  132 . For example, at some router co-location facilities, the choices for physical links may include 1 Gbps 1000B ASE-LX (1310 nm) single-mode fiber connections over single-mode fiber, and 10 Gbps 10GBASE-LR (1310 nm) single-mode fiber connections over single-mode fiber, and the connectivity coordinator  114  may allow the client to choose between the 1 Gbps option and the 10 Gbps option. In other cases the client may be allowed to request any arbitrary bandwidth and the connectivity coordinator  114  may respond to the request by indicating the bandwidth it is able or willing to provide. In one implementation the connectivity coordinator may not provide any guarantees of bandwidth availability and instead, for example, indicate to the client that a best-effort approach will be used—i.e., the connectivity coordinator will try to provide as much bandwidth (up to the customer&#39;s desired limit) as possible. In another implementation, the connectivity coordinator may indicate that more than one physical link may be needed—e.g., if the customer requests 20 Gbps and the maximum bandwidth available over a single cable is 10 Gbps. It may also be possible to set up multiple physical links distributed over different router co-location facilities  132  in response to a single request for dedicated connectivity—e.g., if a particular client has access to client-side routers  142 A and  142 B at respective facilities  132 A and  132 B, one or more physical links may be set up at each facility if needed or requested. The interface provided by connectivity coordinator  114  may allow clients to specify whether distinct physical locations should be used to provide the desired connectivity, and if so, how many locations should be used. 
     The client may in some embodiments also provide an availability requirement  363  and/or a multi-path requirement  365 . The availability requirement may be expressible in any of various metrics such as desired maximum network outage limits (e.g., one hour per year maximum outage time) or mean time between outages. A multi-path requirement  365  may indicate the number of physical links that should be set up between a client-side router  142  and an endpoint router  132 . Multiple physical links may for example be requested for performance (e.g., so that traffic from the client network  162  may be load-balanced or otherwise distributed over multiple physical paths, thereby reducing network congestion), for higher availability (e.g., by providing multiple paths, an alternate path may be available as a backup path in case of a failure at one of the physical links), or a combination of performance and availability reasons. In addition to specifying how many physical links are needed, a client may also specify the manner in which traffic is to be distributed among them. In a case where two paths are requested, for example, the client may specify whether they should be established in an active/active mode (e.g., where Border Gateway Protocol (BGP) Multipathing is used to balance load across the two links, and in case of a failure, one link takes over the other&#39;s traffic), or in active/standby mode where only one of the links is in use at a time, and the second link is activated only in the event of a failure at the first link. Default choices (e.g., active/active) may be indicated via the interface to the client in some implementations, so that the client need not explicitly specify the type of multi-path setup if the client does not wish to do so. In some cases, indicating a multi-path requirement  365  may negate the need for (or contradict) an availability requirement  363 , so the client may be allowed to specify only one of these two types of options. 
     In one embodiment, in order for example to further simplify the tasks that the client may need to do to establish connectivity at their end, or to optimize performance, the connectivity coordinator  114  may also be able to provide configuration instructions, suggestions, and/or preferred settings for the specific type of networking equipment that the client may have. In such an environment, a client may provide client network equipment information  367  to connectivity coordinator  114 , which may for example consult a database of configuration data (e.g., database  115 ) to look up configuration instructions for the equipment, and provide configuration suggestions or instructions to the client. If a client indicates via information  367  that they wish to use a particular type or class of router from a particular vendor (e.g., a Cisco router, a Juniper router, or a Yamaha router), for example, the connectivity coordinator may be able to provide vendor-specific configuration hints for the particular type of router or for a particular version of software running on that particular router. Such hints may include examples of how to configure or verify BGP settings, tunneling-related settings, IKE (Internet Key Exchange) settings, and may also include instructions on how to test that the particular vendor&#39;s device is operating effectively. Troubleshooting hints and/or tuning hints such as preferred buffer sizes and the like that may be vendor-specific and/or device-specific may also be provided by connectivity coordinator  114  in some embodiments. Since at least in some environments the provider network  105  may have a large number of clients using a wide variety of networking equipment, the connectivity coordinator  114  may be able to build up a knowledge base covering a wide variety of networking equipment configurations, the kinds of client-side settings that work best with the provider network&#39;s own equipment, and so on, which may be very helpful clients that are embarking on the process of linking their client networks  160  to the provider network  105 . In some implementations, additional specifications  368  for the desired connectivity may also be included in a client request—e.g., specifications of a desired start time or end time for the dedicated connectivity, or an acknowledgement that a particular BGP version and/or Bidirectional Forwarding Detection (BFD) are supported in the client network  162 . 
     In various embodiments information similar to that shown in  FIG.  3    may be communicated in multiple steps to the connectivity coordinator  114 —e.g., first location information and desired bandwidth may be communicated, then the connectivity coordinator may provide a response with a list of possible options, and then from among the possible options the client may choose one option and provide additional specifications in subsequent messages. The information may be transmitted to the connectivity coordinator  114  from the client (or from a third party on behalf of the client) using any available network path—for example a path  175  that may include portions of the public internet. Some or all of the interactions between the client and the connectivity coordinator  114  may be encrypted in various embodiments. In some cases where the client does not currently have a client-side router already available at an appropriate router co-location facility  150 , further interactions may be required between the client and the connectivity coordinator  114 , wherein for example the connectivity coordinator provides suggestions for third-party network service providers that the client may be able to use to obtain access to a suitable router. 
       FIG.  4    illustrates an example of constituent elements of a response that may be generated to a request for dedicated connectivity from a client, according to at least some embodiments. The illustrated example shows the connectivity coordinator  114  sending a response  451  back to the requesting client device  148 , and also an optional notification  452  that may be sent to an operator or manager of a router co-location facility  150  in some implementations. Having examined the various parameters or properties of the dedicated connectivity requested by the client as illustrated in  FIG.  3   , the connectivity coordinator  114  may eventually decide on a particular endpoint router  132  that may be appropriate for a physical link to be set up to the client&#39;s network. For example, in  FIG.  1   , endpoint router  132 A at router co-location facility  150 A may be chosen to provide physical connectivity to client network  162 A. Response  451  may include any combination of physical link configuration instructions  471 , authorization information  482 , a connection identifier  482 , and device-specific configuration instructions  483 . The physical link configuration instructions  471  may for example pinpoint the exact physical coordinates where a cable originating from a client-side router such as router  142 A is to be attached: an identification  467  of the physical port (e.g., “port  3 ” or “the third port from the left”), a cage identifier  461 , a rack identifier  463 , and a patch panel identifier  465 . 
     In many cases networking equipment such as routers  132  and  142  are housed in secure environments where not everyone may have physical access. In such cases, authorization information  481 , which may for example comprise a legally-binding agreement to allow a technician to access the endpoint router  132 A may be provided to the client. In some environments a document similar to or derived from a commonly-used standard authorization communication format called “LOA-CFA” (Letter Of Authority and Customer Facility Assignment) may be used for authorization information  481 . Authorization information  481  may itself include the physical link coordinates such as port identifier  467 , cage identifier  461 , rack identifier  462 , and patch panel identifier  465  in some cases. The response  451  may also include a connection identifier  482  corresponding to the requested dedicated connectivity, which may be used in further communications from the client to the connectivity coordinator  114 , such as a request for establishment of logically-isolated paths via the setUpLogicalConnection API described earlier and discussed further in conjunction with the description of  FIG.  5    below. 
     In some embodiments the connectivity coordinator  114  may also provide configuration instructions  483  for client-side network equipment. Such instructions may be provided in cases where client network equipment information  367  was earlier provided to the connectivity coordinator  114 , and may also be provided for a default set of devices (e.g., the most commonly used types of routers) even the client did not previously provide details of the client-side equipment in some implementations. Depending on the specifics of the endpoint router  132  selected for the physical connection, different sets of client-side configuration settings may in general be appropriate even for a given piece of client-side networking equipment, and the connectivity coordinator may consult its configuration knowledge base to choose the appropriate instructions after the endpoint router  132  has been selected. 
     As described earlier, authorization may be required to set up physical connectivity to an endpoint router  132  in some environments. In some embodiments, authorization information  481  may also (or instead) be sent to an operator  433  of the router co-location facility  150  by connectivity coordinator. In some jurisdictions legal constraints may prevent such direct communication between the connectivity coordinator  114  and co-location facility operators  433 , in which case the authorization information may, if required, be provided by the client to the operator  433 . 
     In many cases a client may be interested in using resource collections  120  for a variety of different purposes—for example, a software vendor may wish to use one set of resources  112 A to set up a development and build environment for its software engineers, another set of resources  112 B for an intranet for storing and sharing corporate information internally within the company, and a third set of resources  112 C (not shown in  FIG.  1   ) for a web site that may be accessed by the software vendor&#39;s customers. Such a client may desire, for example for administrative purposes, accounting/billing purposes, and/or security purposes, that the network traffic for each set of resources  112  be isolated from the traffic for the other sets of resources  112 . For example, the software vendor may wish to ensure that the build-related traffic be kept separate from the intranet traffic, that traffic from the build machines or resources  112 A may not be permitted to reach one or more intranet servers  112 B, and so on. At the same time, such a client may wish to utilize the same dedicated physical connectivity provided via an endpoint router  132  for all these different functions, i.e., the client may wish to establish multiple logically-isolated network paths that all share the same physical link similar to cross-network link  191  established for dedicated connectivity to resource collections  120 . In some embodiments, the interface set up by connectivity coordinator  114  may be capable of providing support for various operations related to such logically-isolated paths, such as creating, modifying, deleting, and retrieving or querying the state of the paths. 
       FIG.  5    illustrates an example of constituent elements of an isolation request  551  for a logically-isolated network path that may be sent to connectivity coordinator  114 , according to at least some embodiments. Prior to making a request for a logically-isolated network path, a client may have established a physical link to obtain dedicated connectivity, as illustrated in high-level step  211  of  FIG.  2   , and may have obtained a connection identifier  482  during the physical-link establishment process. That connection identifier may be included in the request  551  in the illustrated embodiment. Request  551  may also comprise various selection criteria such as any combination of a VLAN tag  501 , a BGP ASN  511 , a set of network prefixes  521 , pairing information  531 , virtual private gateway information  541 , and/or other information that may be useful in network isolation in various embodiments. 
     A Virtual Local Area Network (VLAN) is a method often used for creating multiple logically-isolated networks within a single physical network. A tag or identifier called a VLAN tag may be inserted into the header of each packet being transmitted within a given VLAN environment to enable switches or other network devices to identify the VLAN to which the packet belongs. In one embodiment, connectivity coordinator  114  may require the client to provide a unique VLAN tag  501  for each logically-isolated network path that the client wishes to establish, i.e., a client may not be permitted to use the same VLAN tag for multiple logically-isolated paths. In one implementation the VLAN tag  501  may be required to comply with a standard, such as the Ethernet 802.1q standard. 
     A client may also be required to provide a BGP Autonomous System Number (ASN)  511 . As noted earlier, an Autonomous System (AS) is a collection of connected Internet Protocol (IP) routing prefixes under the control of one or more network operators that presents a common, clearly defined routing policy to the Internet. A unique ASN is typically allocated to each AS for use in BGP routing. ASN  511  may be public (i.e. may be exposed to various routers of the public Internet) or private (exposed only to routers of the provider network  100  and the client network  162 ), depending on the type of logical connectivity the client wishes to establish in various embodiments. The client may also provide a set of network prefixes  521  to be advertised for the logically isolated network, e.g., in accordance with BGP or another routing protocol. Pairing information  531 , indicating for example whether the desired logically-isolated path is to be paired in an active/active or active/standby mode with any other path, may also be included in request  551  in some embodiments. In some implementations the provider network may support establishment of virtual private gateways to support VPN (virtual private network) functionality between a client network  162  and resource collections  120 , and request  551  may also include an identification of such a virtual private gateway to be used for the logically-isolated network path. In some embodiments Multiple Protocol Label Switching (MPLS) techniques may be used to implement logical network isolation. While the exemplary elements illustrated in  FIG.  5    may be applicable in environments where BGP and related protocols are in use, in other embodiments other network isolation mechanisms (e.g. any other techniques usable for connecting to virtual private clouds or VPNs) may be supplied by the client and used by connectivity provider for logical network isolation. In the example setUpLogicalConnection API call described earlier, some or all of the various elements of request  551  may be included for example in fields of the LogicalConnectionParameters object passed as a parameter. 
     In one embodiment, after receiving the request  551  for establishing a logically-isolated network path, connectivity coordinator  114  may perform a set of operations, such as updating connectivity database  115 , propagating appropriate routing information to various routers of provider network  105 , refreshing various routing-related caches, and the like, to complete the requested configuration. After establishing the logically-isolated network path successfully, in some embodiments the connectivity coordinator  114  may send a confirmation message back to the client indicating that the requested dedicated connectivity and/or logical isolation has been successfully provisioned.  FIG.  6    illustrates an example of contents of such a confirmation message  651  indicating that requested connectivity has been established, according to at least some embodiments. In the illustrated example the physical connection confirmation details  601  may confirm some of the information related to the physical link established at the request of the client, such as port identifier  467 , rack identifier  463 , available bandwidth, etc. Logical connection confirmation details  621  may confirm properties of the logically-isolated network paths, such as VLAN tag  501 , BGP ASN  511 , network prefixes  521 , pairing information  531 , and virtual private gateway information  541 . In the illustrated example confirmation message  651  also includes the connection identifier  482  and support information  611 —e.g., information that the client may use to obtain help in case of a traffic interruption, poor performance, or other issue that may arise. Confirmation messages  651  may exclude any combination of the elements shown in  FIG.  6    in different embodiments, and may include additional information in some embodiments. In one embodiment multiple confirmation messages may be sent by connectivity coordinator  114 —e.g., a first confirmation message may be sent after the physical link is established, and a second confirmation message may be sent after the logically-isolated network path has been established. Connectivity coordinator  114  may also send instructions to the client to verify or validate that the desired connectivity is functioning correctly at the client end—e.g., in en embodiment where resources  112  include virtual compute servers with associated public and/or private IP addresses, such instructions may direct the client to start up a virtual compute server and ping one of its IP addresses. 
     Example of Logically-Isolated Network Paths Over Shared Physical Link 
       FIG.  7    illustrates an example of two logically-isolated network paths  752 A and  752 B sharing a single dedicated physical link such as a cross-network connection established using an interface provided by connectivity coordinator  114 , according to at least some embodiments. In the environment shown in  FIG.  2   , the client requires connectivity to be established and maintained between internal network  732  and a restricted-access resource farm  712 . At the same time the client has set up a de-militarized network zone (DMZ)  722  (which may also be termed a perimeter network)—a sub-network of client network  162 A that may expose some of the client&#39;s services to the public or untrusted Internet via public-access resource farm  702  within provider network  105 &#39;s data centers. To ensure that the traffic for both the restricted-access resource farm  712  and the public-access resource farm  702  meets desired performance, security and cost requirements, the client may first use the interface provided by connectivity coordinator  114  to establish a cross-network connection  791  between client-side router  142 A and endpoint router  132 A, using for example the steps described in  FIG.  2   . The client may further use other components of the interface to establish two logically-isolated network paths that share the cross-network connection  791 : path  752 A for traffic between DMZ  722  and the public-access resource farm  702 , and path  752 B for traffic between the client&#39;s internal network  732  and restricted-access resource farm  712 . 
     In some embodiments multiple dedicated physical links such as cross-network connections  791  or  191  may be set up on behalf of a single customer, either within one router co-location facility  150  or across multiple router co-location facilities. For example, a multinational corporation may have office facilities in several different countries, which may all benefit from dedicated connectivity to a set of resource collections  120 ; in such as a case, one or more dedicated physical links may be set up for respective geographically separated office locations. A single physical link may be shared across numerous logically-isolated paths such as paths  752  of  FIG.  7   . Furthermore, a given resource collection such as a resource farm  702  or  712  may be accessible via a plurality of logically-isolated paths  752 , where some of the logically-isolated paths  752  may use different dedicated physical links  791 . 
     Example of Web-Based Interface 
       FIG.  8    is an illustration of a portion of an exemplary web-based interface that may be provided by connectivity coordinator  114  in some embodiments. As noted earlier, the interface implemented by connectivity coordinator  114  to provide connectivity services may be exposed to clients as a set of web pages in some embodiments. Web page  800  of  FIG.  8    is a representation of an example of one such web page that includes several form fields that a client may fill out to provide details about desired dedicated connectivity requirements. In some implementations the submission of form data via an interface like web page  800  may result in an invocation of one or more API calls similar to those listed earlier in conjunction with the description of element  201  of  FIG.  2   . 
     In area  803  of web page  800 , a friendly greeting and overview message may be provided. Form fields  805  may be provided to allow the client to specify a physical location where the dedicated connectivity is desired. Using form field  807 , the client may specify desired bandwidth, for which a default value of 1 Gbps is shown pre-selected in  FIG.  8   . Form fields  809  may be used to provide optional pairing or multi-path information; as shown, a default of two connections in active/active mode is pre-selected. For fields  811  may allow the client to specify a vendor name and model for a client router to be used for a dedicated physical link. Form field  813  may allow the client to identify a network service provider that may also be involved in setting up the dedicated connectivity—for example, an operator of the router co-location facility that may be used. In some embodiments, when the client fills in the address information in form fields  805 , the connectivity coordinator  114  may automatically fill out the network service provider form field  813 , or may populate a set of drop-down options from which the client may select a preferred provider via form field  813 . The client may submit the completed form using submit button  815  in the illustrated example. In some implementations employing a web page interface, several different web pages may be employed during the process of establishing the desired physical and logical connectivity. As the client fills out one form entry, the connectivity coordinator may be able to customize or narrow the set of options available for subsequent form entries. 
       FIG.  9    is a flowchart of a method for providing connectivity-related services, according to at least some embodiments. As shown in element  900  in the flowchart, an interface that defines a set of connectivity operations may be implemented, for example by a connectivity coordinator  114 . The connectivity operations provided via the interface may include services to set up, query, modify, disable and tear down various types of physical and logical connections in various embodiments. The interface may comprise any combination of a set of APIs, a web-based or standalone GUI, command-line tools, and the like. 
     A request for dedicated connectivity may be received in accordance with the interface, as shown in element  910 . For example, in an environment where the interface is web-based, the request may comprise one or more HTTP or HTTPS requests, while in a different embodiment, the request may comprise one or more method calls from a program coded and executed on behalf of the client. The request may comprise an enumeration of several details that may be needed to make a decision as to where and how the dedicated connectivity may be provided, and which business entities such as third-party network service providers or network data center operators may need to be involved. For example, the request may specify a desired physical address at which a client-side router  142  is available for use, a desired bandwidth, and various other requirements. 
     On receiving the request, a target endpoint router  132  of a provider network  105  may be selected, through which a route to provide the desired dedicated connectivity to the client may be configurable, as shown in element  920  of  FIG.  9   . The target endpoint router may be selected based on any of a variety of factors in different embodiments, including physical location, measured and/or expected bandwidth utilization levels, costs, previous positive or negative experiences with the operator of the facility where the router is located, compatibility with the client&#39;s networking equipment and the like. 
     A set of configuration information and instructions may then be generated for setting up a physical link to the target endpoint router, as shown in element  930 , and a response may then be transmitted (element  940 ). In some embodiments the response may be submitted only to the requesting client, while in other embodiments a response may be submitted to an operator of a router co-location facility  150  where the physical link is to be established, or responses may be submitted to both the requesting client and the facility operator. The response may include data identifying the particular physical port, cage, rack, and/or patch panel where a physical cable may be attached in some implementations. Authorization information, e.g., granting permission to a technician to access the endpoint router may be included in the response, or may be made accessible via the response. 
     In one implementation, after the physical link is established, a confirmation message indicating that the desired connectivity has been established successfully may be transmitted to the client (element  950  of  FIG.  9   ). In other implementations, a confirmation message may be generated after one or more logically-isolated network paths have been established using the newly established physical link. 
       FIG.  10    is a flowchart of a method for providing connectivity-related services including guidance on configuring a client network device, according to at least some embodiments. An interface that allows a client to make a variety of connectivity-related requests, including requests for assistance in configuring one or more network devices that may be used to establish dedicated connectivity with a provider network, may be implemented as shown in element  1000 . A request that provides an identification of networking equipment (e.g., any combination of a vendor name, a model name, and a software version identifier for software running on the networking equipment) available for use by the client may be received (element  1010 ) in accordance with the interface. Such a request may also include other details of the connectivity requested by the client, such as a desired bandwidth, availability/redundancy requirements, and the like. 
     In response to the request, in some implementations a connectivity coordinator  114  may query a database of configuration information, for example using a combination of vendor name, model name, software version and/or connectivity requirements (element  1020 ). If appropriate configuration guidance is found, e.g., based on the identification information provided in the request, a response containing the configuration information or instructions may be generated (element  1030 ) and transmitted to the requesting client (element  1040 ). In some implementations, the database of configuration information may include an inventory of where (i.e., by which clients) different types of networking equipment are being used; in such a case, a record indicating that the requesting client uses the specified equipment may be inserted into the database (element  1050 ). In some environments additional information on experiences with different types of networking equipment, such as surveys of client satisfaction with their networking equipment, mean times to failure, availability data, and the like may also be maintained in a knowledge base by connectivity coordinator  114 , and some or all of this additional information may also be made available via the interface. 
     Interactions with Last-Mile Connectivity Providers 
       FIG.  11    illustrates an example of a system  1105  including a provider network  1100  to which connectivity may be provided from client networks such as  1162 A and  1162 B through “last-mile” connectivity providers (e.g.,  1150 A,  1150 B, and  1150 C), according to at least some embodiments. In many environments, client devices such as  1148 A and  1148 B may be provisioned within networks (e.g.,  1162 A and  1162 B) that may not have private paths available from their client-side routers  1142  to router co-location facilities (similar to facilities  150  of  FIG.  1   ) where endpoint routers such as  1132 A and  1132 B may be located. This may be especially likely in the case of relatively small client businesses, or when client business premises are located in areas that are somewhat remote from router co-location centers. Such client networks  1162  may have access via shared network paths (e.g., the portions of the public Internet, including for example portions of path  1175 ) to various resource collections  1120  of the provider network  1100 , but the operators of the client networks may wish to avail themselves of the advantages of dedicated paths to the resource collections. Various third party connectivity providers  1150  (i.e., business entities other than the provider network&#39;s operator) may be capable of providing the dedicated paths to the endpoint routers  1132 —for example, in  FIG.  11   , connectivity provider  1150 C is shown providing a dedicated or direct path  1149  between endpoint router  1132 B and client network  1162 B. Such connectivity providers may help clients to bridge the gap between the client networks  1162  and the private paths  1170  (e.g., paths  1170 A,  1170 B,  1170 C and  1170 D, similar to paths  170  of  FIG.  1   ) available between the endpoint routers  1132  and the resource collections  1120 . These third party connectivity providers may be referred to as “last-mile” connectivity providers (or “last-kilometer” connectivity providers in environments where metric distance units are more popular), as they are often responsible for implementing physical network connectivity closest to the client premises, and therefore furthest from the premises of major network infrastructure providers. In this document, last-mile connectivity providers may also be referred to using the abbreviation “LMCP”. 
     Identifying which, if any, last-mile connectivity providers may be available and willing to link a client&#39;s network to the provider network  1100  may often be cumbersome from a client&#39;s perspective. In some cases, a number of LMCPs may operate in the vicinity of the client&#39;s premises, but only a subset may be supported or preferred by the operator of provider network  1100 . In the embodiment illustrated in  FIG.  11   , connectivity coordinator  1114  may be operable to implement an interface defining a variety of connectivity-related services, which may allow clients to easily determine which LMCPs  1150  can be used to connect to provider network  1100 . Such an interface may further allow the clients to establish desired dedicated connectivity (e.g., over a direct path  1149 ) to resource collections  1120  with the help of selected last-mile connectivity providers. Connectivity coordinator  1114  may implement one or more databases  1115  to store connectivity-related information, including for example a directory of last-mile connectivity providers  1150  and their offerings. The interface may be published or made available to clients by connectivity coordinator  1114  using any appropriate technique, such as one or more email messages to all the clients of the provider network  1100 , establishing a web site or web page with the details of the interface, and so on. The interface itself may, for example, be programmatic, and may comprise any combination of a collection of APIs, one or more web pages, command-line tools, an installable graphical user interface, or the like. Connectivity coordinator  1114  may itself be resident outside provider network  1100  in some embodiments, and in other embodiments it may be incorporated within the provider network  1100 . 
     Using the interface, e.g., from one of the client devices  1142 A, a client may submit a request for dedicated connectivity, e.g., over a path  1175  that may include links of the public Internet. The request may, for example, include the physical address or addresses at which the client desires dedicated connectivity. In response to the request, the connectivity coordinator may be operable to identify one or more LMCPs  1150  that may be available to establish dedicated connections between the provider network  1100  and the requesting client&#39;s network (e.g.,  1162 A), and generate and transmit a response that lists the selected LMCP or LMCPs. The selected LMCP may operate or manage one or more routers that happen to be co-located with one of the endpoint routers  1132  of the provider network  1100 , or may have the ability to set up such routers if they are not already available. In some embodiments the connectivity coordinator  1114  may allow the client to select one LMCP from among a set of available LMCPs, while in other embodiments the connectivity coordinator  1114  may determine the specific LMCP or LMCPS that should be used, and inform the client of the determination. Later, after the dedicated connectivity has been set up, for example via steps similar to those outlined in  FIG.  2   , the connectivity coordinator  1114  may in some embodiments provide a confirmation to the client indicating that the desired connectivity has been verified. The interface may be used for communication between the client and the connectivity coordinator  1114  during any of the stages of dedicated connectivity establishment and use—e.g., a client may query the state of a requested connection or an established connection using the interface, and may request various connectivity modifications, disabling and enabling of connectivity, and the like. Responses to the client requests may also be formatted in accordance with the interface. 
     The connectivity coordinator  1114  may, for example, look up LMCP information in database  1115  to respond to the initial request for dedicated connectivity. In cases where multiple LMCPs  1150  are available, the connectivity coordinator  1114  may in some implementations provide an unordered enumeration of all available LMCPs to the client. In other implementations the available LMCPs may be sorted according to any of a variety of criteria based on details of the client&#39;s request and on the connectivity coordinator&#39;s LMCP knowledge base. For example, if the connectivity provider  1114  is aware of service quality rankings or ratings of the various LMCPs, it may sort the LMCPS from highest to lowest quality. If the connectivity provider  1114  has pricing information available for the different LMCPs it may rank them according to price, and so on. Connectivity coordinator  1114  may in some implementations periodically query clients for quality rankings or ratings of different LMCPs and store the results of such surveys in its database  1115 , or it may monitor outages or support requests to establish its own quality rankings. In one implementation in which clients may specify desired connectivity establishment times (e.g., the logical equivalent of “I need this connectivity by Aug. 1, 2011 at 8 AM EST”), the connectivity coordinator may be able to eliminate some LMCPs from the list of available LMCPs based on how quickly the LMCPs have been known to establish connectivity in the past. In some embodiments the interface supported by the connectivity coordinator  1114  may allow clients to query its knowledge base of LMCPs. In addition to the paths illustrated in  FIG.  11   , in many environments there may be several other alternative network paths available between the client networks  1162  and various components of the system  1105 —for example, the connectivity requests may be transmitted to the connectivity provider  1114  over a path that includes public or shared links, and various services provided at resource collections  1120  may be accessed over public or shared links as well. 
     LMCP-Related Communications with the Connectivity Coordinator 
       FIG.  12    illustrates an example of constituent elements of an initial request  1251  for dedicated connectivity through a connectivity provider  1150 , according to at least some embodiments. As shown the request comprises location information  1260  for the client network  1162 , and optional connectivity details  1261 , an optional start time  1268 , and an optional end time  1269 . The connectivity coordinator  1114  may use location information  1260  as the primary criterion for querying its LMCP database to identify available LMCPs. Optional connectivity details  1261  may include requirements similar to those shown in  FIG.  3   , for example, bandwidth requirement  361 , availability requirement  363 , and/or multi-path requirement  365 . In some embodiments the client may also specify a desired start time  1268  and/or a desired end time  1269 —for example, indicating that the dedicated connectivity is only going to be needed for 3 months starting on Jan. 1, 2011. In some cases the start and end times may indicate that the client only desires to use the dedicated connectivity part of the time—e.g., the start time and end time may be specified as “8 AM-8 PM, Monday through Friday”. In some implementations where desired start times  1268  are indicated by the client, end times  1269  may not be required. Timing requests comprising desired start and/or end times may be sent separately from the initial request  1251  in some embodiments. 
       FIG.  13    illustrates an example of constituent elements of a response  1301  to a dedicated connectivity request that includes information on available connectivity providers  1150 , according to at least some embodiments. The response  1301  may comprise a list of one or more LMCP details records  1361 , e.g.,  1361 A and  1361 B, that the connectivity coordinator  1114  may have found to meet the request  1251  from the client. Different types of information regarding the available LMCPs may be provided to the client in various embodiments. For example, LMCP details record  1361 A may comprise an identification (e.g., name and contact information)  1311 A of the LMCP  1150 A, pricing information in fields  1321 A and  1321 B, estimated connectivity establishment time  1341 A, and/or a satisfaction rating  1351 A. Pricing information may be split into a recurring price component  1321 A (e.g., “X dollars per month, independent of the actual usage”) and a non-recurring price component  1331 A (e.g., based on measured bandwidth usage by the client). In some implementations the pricing information may be broken down further into components that are to be paid to the LMCP  1150 A directly by the client, and components that are to be paid to the operator of provider network  1100 . The interface supported by coordinator  1114  may allow clients to submit pricing-related queries as separate requests in some implementations. The earliest time at which the LMCP  1150 A and/or the provider network  1100  operator may be able to establish the desired dedicated connectivity may be indicated via field  1341 A. In some cases a satisfaction rating  1351 A (e.g., based on surveys of the clients of the LMCP  1150 A) may be included, which may be helpful to the client in selecting among available LMCPs. Details record  1361 B may include similar fields as record  1361 A for a different LMCP, e.g., for LMCP  1150 B. 
       FIG.  14    illustrates an example communication from a client identifying a selected connectivity provider  1150 A, that may be generated by the client after receiving a response  1301 , according to at least some embodiments. Selection notification  1451  may also be formatted in accordance with the interface implemented by connectivity coordinator  1114 , e.g., as an API call or a web form selection.  FIG.  15    illustrates example communications from connectivity coordinator  1114  to an LMCP  1150  and the client after the client has selected the LMCP, according to one embodiment. As shown, in response  1551  to the client, the connectivity coordinator  1114  may provide confirmation  1583  of the selection of the LMCP. In one embodiment, the connectivity coordinator  1114  may determine the LMCP  1150  to be used, e.g., based on the client&#39;s location information, and may not require that the client make a selection; in other embodiments, the connectivity coordinator  1114  may wait for the client&#39;s selection or confirmation before making the determination of the LMCP. In some implementations the client may suggest or recommend one or more LMCPs in the initial request for dedicated connectivity (e.g., request  1251  of  FIG.  12   ), and the connectivity coordinator  1114  may determine the LMCP to be used based on the initial request. A connection identifier  1581  may also be provided to the client in response  1551 . In some embodiments authorization information  1582  allowing physical access to the network provider&#39;s endpoint router  1132 , similar to the authorization information  481  shown in  FIG.  4   , may be provided to the client as well. In notification  1552  sent to the selected LMCP  1150 , connectivity coordinator  1114  may also provide authorization information  1582 , as well as physical link configuration instructions  1571  (similar to physical link configuration instructions  471  of  FIG.  4   ) which may include port, cage, rack and/or patch panel identifiers  1567 ,  1561 ,  1563  and  1565  respectively for the endpoint router  1132  to which a physical link may be established by or on behalf of the selected LMCP. In some embodiments the authorization information  1582  may be sent to either the client or the LMCP, but not both. 
     After communications similar to those shown in  FIG.  15    are received by the client and/or the selected LMCP  1150 , a path (similar to direct path  1149  of  FIG.  11   ) comprising a dedicated physical link may be established between equipment of the provider network (such as an endpoint router  1132 ) and the client network  1162  using the selected LMCP&#39;s network and/or equipment in one embodiment. As desired, one or more logically-isolated paths, similar to those discussed in conjunction with the description of  FIGS.  5  and  7    may then be established using the newly-established dedicated physical link. In some implementations, the connectivity coordinator  1114  may verify, e.g., by exchanging one or more network packets or messages with the client and examining the routes taken by the messages, that the desired dedicated connectivity has been provided, and may send a confirmation message to the client and/or the LMCP  1150  indicating this accomplishment. 
     In environments where timing constraints (such as start times and/or stop times) were requested by the client, connectivity provider  1114  may also be operable to implement those timing constraints, e.g., by scheduling routing changes or making other configuration changes at the appropriate times. For example, in one environment where BGP is used as a routing protocol, a set of network prefixes for the client network may be advertised at or shortly prior to a desired start time to enable or disable the dedicated connectivity. In some implementations, the dedicated connectivity provided to a client with the help of an LMCP may have an associated bandwidth limit, and the interface supported by the connectivity coordinator  1114  may also enable clients to make bandwidth modification requests—e.g., to request a higher or lower rate of traffic than initially agreed upon. In response to such requests the connectivity coordinator  1114  may dynamically change configuration settings at one or more devices to comply with the new bandwidth requirement. In one embodiment the connectivity coordinator  1114  may itself monitor the rate at which traffic flows to a client network  1162 . If traffic over a measured period of time reaches a threshold (e.g., 80% or more of the maximum allowed traffic), the connectivity coordinator  1114  may inform the client that a bandwidth modification may be advisable, and the client may in turn request a bandwidth increase using the interface. In some implementations the connectivity coordinator  1114  may also be configure to notify a client if it may be advisable to lower the bandwidth limit associated with a dedicated direct path, e.g., if measurements indicate that the client appears to use only a small fraction of the bandwidth it requested. 
     Example Web Interface for Initiating LMCP Selection 
       FIG.  16    is an illustration of a portion of an exemplary web-based interface that may be provided for initiating connectivity provider selection, according to some embodiments. As shown, the web-based interface may comprise a web-page  1600  with several form fields that may be presented to the client by connectivity coordinator  1114 . The web page may include a welcome message area  1603 , and form fields  1605  for the client to specify a physical address where dedicated connectivity is desired. In fields  1607 , the client may indicate whether assistance in selecting a connectivity provider is desired. Bandwidth requirements may be specified in fields  1609 , and timing-related requirements for the dedicated connectivity, such as a desired start time and/or a desired end time, may be specified in field  1611 . The submit button  1615  may be used to submit the completed form to the connectivity coordinator  1114 . 
     In one embodiment, the submission of such a form may result in the invocation of one or more APIs at the connectivity coordinator similar to APIs API-1 through API-18 listed in conjunction with the description of  FIG.  2   . Some additional APIs, including some LMCP-specific APIs and APIs to provide dynamic modification of existing connections and/or pricing-related operations may also be supported in some implementations, for which example invocations may include the following: 
     [API-21] ProviderList providerList=getConnectionProviders(CustomerID customerId, CustomerLocationRecord location);
 
The getConnectionProviders API may be used to find available LMCPs based on the location information specified in a CustomerLocationRecord object.
 
[API-22] RequestStatus status=setConnectionProvider(ProviderId providerId, CustomerID customerId, RequestId requestId);
 
The setConnectionProvider API may be used to specify that a particular LMCP identified by its ProviderId has been selected by the customer.
 
[API-23] RequestStatus status=setConnectionStartTime(ConnectionId connectionID);
 
The setConnectionStartTime API may be used to specify a start time for the dedicated connectivity.
 
[API-24] RequestStatus status=setConnectionEndTime(ConnectionId connectionID);
 
The setConnectionEndTime API may be used to specify a desired end time for dedicated connectivity.
 
[API-25] PricingInfo pricingInfo=getConnectionPricingInfo(ConnectionId connectionID);
 
The getConnectionPricingInfo API may be used to query pricing-related information for an existing connection or for a connection that has not yet been established.
 
     In some embodiments, APIs such as those for which examples are provided above may be available for use directly by clients, LMCPs  1150  and/or other network providers, or by facility providers such as operators of router co-location facilities  150 . In some implementations multiple layers of interfaces may be supported, allowing clients to request some connectivity-related operations using a web interface, for example, and to perform or request other operations using an API. 
       FIG.  17    is a flowchart of a method for enabling clients to select connectivity providers, according to at least some embodiments. The method (as shown in element  1700  of  FIG.  17   ) comprises implementing an interface that defines a set of connectivity operations made available to clients of a provider network  1100  by a connectivity coordinator  1114 . The interface may comprise an API, a command-line interface, a web-based interface, some other GUI, or any other programmatic interface, for example. A request for dedicated connectivity, formatted in accordance with the interface, may be received (element  1702 ). The request may in some cases directly indicate that the requester requires assistance in selecting a connectivity provider. In other cases the request may simply contain some information (such as a physical address where a client wishes to obtain dedicated connectivity) from which the connectivity coordinator  1114  may infer, based on its knowledge of where endpoint routers  1132  of provider network  1100  are physically located, that a connectivity provider may be needed to fulfill the client&#39;s request. As indicated in element  1704 , one or more connectivity providers may then be selected, and a response identifying the selected connectivity provider or providers may be generated (element  1706  of  FIG.  17   ) and transmitted (element  1708 ). In some implementations the response may be transmitted to just the requesting client, while in other implementations a response and/or notification may also or instead be transmitted to the selected connectivity provider. 
     When the client receives the information identifying candidate connectivity providers such as LMCPs  1150 , it may select one (if more than one were identified by the connectivity coordinator  1114 ) and notify the connectivity coordinator of its choice. The connectivity coordinator  1114  may then communicate with the selected LMCP  1150 , and with the client, to coordinate the establishment of a physical link (and in some cases one or more logical connections that use the physical link) to fulfill the client&#39;s connectivity needs. After connectivity has been successfully established, the connectivity coordinator  1114  may in some implementations send a confirmation of the completion of the establishment (element  1710  of  FIG.  17   ). 
     In some embodiments a number of additional capabilities, in addition to connectivity provider selection and connectivity establishment, may be supported via the interface provided by a connectivity coordinator  1114 .  FIG.  18    is a flowchart of a method for providing dynamic connectivity-related services, according to at least some embodiments. The connectivity coordinator  1114  may wait for connectivity-related requests from clients, as shown in element  1800 . When such a request is received, if the request is a supported type of request, the connectivity coordinator  1114  may take the requested action. For example, if a request for dynamic enablement of connectivity is received and supported in the embodiment (element  1810 ), the connectivity coordinator may enable traffic flow, as shown in element  1815 . In some cases enabling or disabling traffic may require interaction or coordination between the connectivity coordinator  1114  and an LMCP  1150 . Similarly, if the request is for disabling connectivity (element  1820 ), the desired change may be put into effect by connectivity coordinator  1114  (element  1825 ). If the request is for a change to the bandwidth limits associated with a client&#39;s dedicated connection path (element  1830 ), the requested change may be implemented, e.g., by making configuration changes at one or more network devices of the provider network  1100  and/or an LMCP. If the request comprises a pricing query (element  1840 ), the connectivity coordinator  1114  may provide the requested pricing information (element  1845 ), which may for example include recurring and/or non-recurring cost information that the provider network operator and/or the LMCP may charge the client. If an invalid or unsupported request is received, as shown in element  1850 , the connectivity coordinator may transmit a response indicating that an unexpected request was received. In each case, as the arrows leading back to element  1800  indicate, the connectivity coordinator eventually resumes waiting for connectivity-related requests. While the determination of the type of request is shown as a series of checks in  FIG.  1800    for simplicity (first checking for dynamic enablement requests, then for disablement requests, and so on), in various implementations the request type may be determined in a single step using logic similar to a “case” or “switch” statement in C or Java 
       FIG.  19    is a flowchart of a method comprising responding dynamically to changing traffic levels, according to at least some embodiments. As shown in element  1900 , the connectivity coordinator may monitor traffic rates over the dedicated path set up for a client. If some threshold of traffic is reached or sustained over a period of time (as detected in element  1910 ), the connectivity coordinator may provide an indication to the client that a bandwidth change may be appropriate (element  1915 ). If a request to change the bandwidth is received in response to the indication (element  1920 ), the connectivity coordinator may implement the requested change (element  1925 ). The connectivity coordinator may then resume monitoring the traffic. Each of the interactions illustrated in  FIGS.  18  and  19    between the connectivity coordinator  1114  and the client may be implemented using the interface or interfaces (such as one or more web pages) provided by the connectivity coordinator. 
     Marketplace Enablement for Services Accessible Via Direct Links from Client Networks 
     Clients of provider networks (such as provider network  105  of  FIG.  1    or provider network  1100  of  FIG.  11   ) may in many environments implement applications and services exposed to their own customers outside the provider networks. For example, one client (“Client A”) of a provider network that has set up direct physical links from its client network to the provider network using the techniques described earlier may set up a file backup service using one or more resource collections, and customers of Client A may access the file backup service from the customers&#39; client devices. In some cases some of the potential customers of such a Client A may also be clients of the provider network, and may have set up their own dedicated physical links to the provider network using interfaces similar to those described above. For example, a Client B of the provider network may have such a dedicated physical link (similar to the cross-network connection  191  shown in  FIG.  1   ) set up between its client network and Client B&#39;s resource collections in the provider network, and may be a candidate to be a customer of Client A&#39;s backup service. However, such a Client B may not be aware of the possibility that Client A&#39;s backup service may be made accessible from Client B&#39;s client network using Client B&#39;s dedicated physical link, thereby gaining the performance and security benefits of such dedicated links. In such environments a connectivity coordinator similar to coordinator  114  of  FIG.  1    may support a number of marketplace-related features that, for example, allow services such as the backup service to be advertised, allow clients of the provider networks to subscribe to such services, and make any configuration changes needed to allow the services to be used via the dedicated physical links. 
       FIG.  20    illustrates an example of a system  2000  including a provider network  2005  within which a client has established a service  2008  potentially accessible to other clients via dedicated physical links, according to at least some embodiments. In the illustrated embodiment, Client A may have used some of the interfaces and techniques described above, provided by a connectivity coordinator  2014 , to establish dedicated connectivity via direct link  2049 A from its client network  2062 A to resource collection  2020 A via endpoint router  2032 A. Similarly, Client B may have used the interfaces to establish dedicated connectivity via direct link  2049 B from its client network  2062 B to resource collection  2020 B via endpoint router  2032 B. Within the provider network  2005 , various private paths  2070  such as paths  2070 A,  2070 B,  2070 C and  2070 D may be available between endpoint routers  2032  and resource collections  2020 ; not all the paths may be actively in use at any given time (e.g., routing configuration settings may need to be changed to permit traffic to flow along a given path  2070 ). Client A may have implemented its service  2008  using resource collection  2020 A allocated to Client A, and may be interested in making the availability of the service  2008  known to other clients of provider network  2005  (such as Client B), and adding such subscribers to service  2008 . The term “service-providing clients” may be used in this document to designate those clients (such as client A) that implement a service that can potentially be made accessible via direct links  2049  of other clients of the provider network  2005 . Clients (such as Client B) that are, or may become, customers of the service-providing clients may be termed “service-consuming clients”. In some embodiments the service may be made available to service-consuming clients that may have set up direct links  2049  (similar to link  2049 B) between their client networks (similar to  2062 B) and the provider network  2005 , but may not have their own resource collections allocated. That is, in such embodiments the direct links  2049  may be set up to provide connectivity between the service-consuming clients&#39; networks and various resources and services available within the provider network  2005 , without requiring the service-consuming client to reserve or obtain its own resource collections within the provider network. Such a service may also be available to various potential customers outside provider network  205  via paths that do not include direct links  2049  in some embodiments. A programmable interface implemented by connectivity coordinator  2014  (which may extend or be similar to the interfaces implemented by connectivity coordinators described earlier in conjunction with  FIGS.  1  and  11   ) may be usable by Client A to advertise its service  2008 , and by Client B to discover Client A&#39;s service and subscribe to it. 
     For example, in one embodiment connectivity coordinator  2014  may receive a service advertisement request, formatted in accordance with the interface, from a service-providing client such as Client A, in which Client A may identify and describe various features of service  2008 . In response, connectivity coordinator  2014  may store this information within a database  2015  in some implementations. In some embodiments the connectivity coordinator  2014  may actively propagate or distribute the advertised information to other clients of provider network  2005 , that may for example have agreed (or “opted-in”) to receive notifications of such services as they become available. Such notifications may also be formatted in accordance with the interface. The notifications may include, among other information, pricing indications for service  2008  in some embodiments; for example, billing rates that may be charged by Client A for service  2008 , and/or billing rates that may be charged by the operator of provider network  2005  for providing network connectivity to service  2008 . 
     In some embodiments clients such as Client B may submit service discovery requests formatted in accordance with the interface to connectivity coordinator  2014 , requesting the coordinator to enumerate or list services with certain desired characteristics that may be available from within provider network  2005 . Upon receiving such a discovery request, the connectivity coordinator  2014  may determine (e.g., by consulting or searching database  2015 ) whether any such services are available, and transmit a notification, formatted in accordance with the interface, to the requesting client with the results of its determination. If one or more services such as service  2008  were found, the notification may comprise a list of the services found, and if no services were found, the notification may indicate that result. In some embodiments access policies may be associated with various resource collections and/or the services implemented therein, which may govern who is allowed to access the resource collection or service, or from where such access is permitted. In such embodiments, before responding to a connectivity request or providing any connectivity-related notifications, the connectivity coordinator  2014  may verify whether the action it is taking is in compliance with the applicable access policy or policies. Access policies associated with the resource collections  2020  and/or services  2008  may, in some implementations, be stored in the database  2015 . 
     Subscriptions to services such as service  2008  may also be set up or disbanded using the interface provided by connectivity coordinator  2014  in some embodiments. For example, after a client such as Client B learns about a service, the client may send a subscription request to the connectivity coordinator  2014  via the interface, indicating that the client wishes to start using the service. In response to such a subscription request, connectivity coordinator  2014  may in some implementations verify whether the requested subscription is acceptable (e.g., by communicating with Client A for service  2008  using the interface). If the subscription is acceptable (e.g., if sufficient resources are still available for Client A to respond to a new subscriber&#39;s requests with acceptable performance and quality levels), the connectivity coordinator  2014  may initiate or make one more configuration changes, for example routing-related changes at endpoint router  2032 B, to enable requests from Client B&#39;s network  2062  to flow to the resource collection  2020 A where the service is being implemented or provided. In some environments, depending on policies agreed to between the connectivity coordinator  2014  and the service-providing client, the connectivity coordinator  2014  may perform the configuration changes necessary without verifying the acceptability of the request. After the configuration changes have been completed, in one embodiment the connectivity coordinator may send messages formatted according to the interface to one or both of the participating clients (Client A and/or Client B) confirming that a new subscription has been enabled. The term subscription, as used herein, refers broadly to any mechanism whereby a client receives requested services and pays for the services. A variety of payment or billing options may be implemented for the service  2008  in different embodiments; for example there may be fixed charges per unit time (e.g., per business day) that the service is available, as well as request-based charges (e.g., per HTTP request) or usage-based charges (per megabyte of data transferred for the service). In some embodiments the charges may be based on how far the traffic generated for, or associated with, a given service or service request has to be transmitted—e.g., a different charge may be incurred if a service requested from the U.S. east coast is handled by a resource in the central U.S., than if the service is handled by a resource in Singapore. 
     In one implementation, the client operating service  2008  may provide the connectivity coordinator  2014  with capacity information for the service, e.g., by specifying a number of available customer “slots”, which may indicate how many subscriptions (or connections for subscriptions) may be accepted. As each new subscriber such as Client B is added, the connectivity coordinator  2014  may use up one or more of the slots. For each slot in some such implementations, addressing or routing information such as IP addresses and/or port numbers to be used for accessing the service  2008  may be made available as well. Information about changes to slot availability (e.g., if Client A expands its resources and makes more slots available, or if Client A is performing upgrades or repair to service  2008  and reduces the number of slots available) may be exchanged between service-providing clients such as Client A and connectivity coordinator  2014  using the interface. 
     Using the interface, a variety of other functionality related to services such as service  2008  may be implemented in some embodiments. The interface may be used to drop or cancel subscriptions, for example. Support requests and/or customer feedback such as ratings and rankings related to a service  2008  may be implemented using the interface as well. In some embodiments users of a service  2008  may be allowed to modify their subscriptions (e.g., to reduce the number of concurrent user sessions for which they are willing to pay) and/or submit queries regarding their subscriptions (e.g., “how many gigabytes of data have I backed up so far this month?”) via the interface. Different types of programmatic interfaces (e.g., APIs, command line interfaces, web-based or other GUIs, etc.) may be used to support the service marketplace functionality in different embodiments. In one embodiment clients such as Client A may also be allowed to extend or customize an API to, for example, provide their own branded “look and feel” to a service such as service  2008 . The techniques described earlier in conjunction with the descriptions of  FIGS.  1 - 19    may be used in various combinations to provide service marketplace functionality in various embodiments. For example, the direct links  2049 A or  2049 B may be set up using last-mile connectivity providers (similar to providers  1150  of  FIG.  11   ) in some embodiments. Logically-isolated network paths similar to those illustrated in  FIG.  7    may be set up for clients subscribing to service  2008  in one embodiment, e.g., using requests similar to request  551  of  FIG.  5   . That is, a client such as Client B may wish to restrict traffic generated for a subscribed service to a designated isolated network path, on which only traffic related to the subscribed service is allowed, and such isolation may be implemented using techniques such as VLAN tags described earlier in conjunction with the description of  FIG.  5   . 
     Marketplace-Related Communications with the Connectivity Coordinator 
       FIG.  21    illustrates examples of constituent elements of a service advertisement request  2151  that may be sent to connectivity coordinator  2014  by a client such as Client A using the interface provided by the connectivity coordinator, according to at least some embodiments. As shown, the request comprises a client identifier  2160  of the client implementing the service (such as service  2008 ) that is being advertised. The request may include any of a number of elements providing information about the service in different embodiments, such as a service name  2161  (e.g., “WorldsBestBackups.com” for a backup service), a service description  2162 , pricing information  2163 , service connectivity information  2164 , available slot information  2166 , and a distribution policy  2167 . A service description field  2162  may in some embodiments provide links or pointers to additional collateral regarding the service  2008 , e.g., in the form of web links to documentation on the service, testimonials or reviews for the service, and the like. The service description field may also include any constraints or suggested requirements for clients wishing to use the service—e.g., that the browser software to be used to access the service must implement HTMLS, or that the client should use a T1 line for connections to the service, and so on. 
     Pricing information  2163  may include details such as different rates based on the time of day or the day of the week (e.g., different rates may be charged during peak business hours vs. weekends or evenings), the geographical location of the requesting clients, the type of connectivity used (e.g., public internet connectivity vs. dedicated links) and so on. In some implementations pricing information  2162  may include indications of the different rates may be charged by the distinct providers involved: the service-providing client (e.g., Client A) may have its pricing rates, and the operator of the network such as provider network  2005  may have its own rates. Service connectivity information  2164  may include instructions on how to access the service, e.g., providing URLs, ports and the like. In some embodiments, as noted above, the service-providing client may provide an indication of available slots  2166 —for example, 100 slots may indicate that up to 100 subscribers of a high-bandwidth backup service may be accepted. As the connectivity provider  2014  enables new subscriptions, it may use the available slot information  2166  to determine whether the service  2008  still has enough spare capacity to add another subscriber. In some implementations the available slot information  2166  may include IP addresses and/or ports to be used for each of the slots, and/or a maximum supported bandwidth or data transfer rate for each slot. In one embodiment the service advertisement request  2151  may include an indication of a distribution policy  2167  controlling how (or whether) the information within the advertisement should be propagated—e.g., whether the connectivity coordinator  2014  should send notifications to potential customers (who may or may not have agreed to receive such notifications) on its own, whether it should wait for service discovery requests to send notifications to potential customers, or whether it should wait for requests from the service-providing client to transmit notifications to specified potential customers. 
       FIG.  22    illustrates an example of a service discovery request  2251  that may be sent to connectivity coordinator  2014  by a client (such as Client B) using the interface provided by the connectivity coordinator, according to at least some embodiments. Such a service discovery request may be used by a client to ascertain the types of services that may be available to the client through its direct link or links (such as link  2049 B) to the provider network. The requesting client may include its client identifier  2260  within the discovery request  2251 . In one embodiment the service discovery request  2251  may also include service selection criteria  2261  to allow connectivity coordinator  2014  to restrict the set of services on which information is provided to the client, i.e., to filter out services in which the requesting client may have no interest. Service selection criteria  2261  may include, for example, an enumeration of keywords indicating the types of services of interest (e.g., “backup”, “disaster recovery”, “video delivery”), desired price range, vendor criteria (e.g., the logical equivalent of “Tell me if any services are provided by MyFavoriteVendor.com”), rating or popularity criteria (e.g., the logical equivalent of “Tell me about the 20 most subscribed services”), and the like. In some implementations, by default (e.g., if no service selection criteria are specified) notifications regarding all available services may be provided to a client in response to a service discovery request. 
     In some embodiments a discovery request  2251  may include notification settings  2262 , which may specify how frequently or under what circumstances the requesting client should be notified regarding the availability of services matching the service selection criteria. For example, a client may specify that service availability notifications may be sent to the client only in response to receiving a specific discovery request  2251 , or that such notifications may be sent at some interval (e.g., weekly or monthly) even when no new service discovery requests  2251  have been sent during that period, or that such notifications may be sent whenever a new service matching the selection criteria becomes available. 
       FIG.  23    illustrates an example of constituent elements of a service availability notification  2301  that may be sent by a connectivity coordinator  2014  to a client, according to at least some embodiments. Such a notification may be sent to a client via the interface in response to a specific service discovery request  2251  in some embodiments; in other embodiments it may be sent periodically, or whenever a new service becomes available, or when a service advertisement request  2151  is received at the connectivity coordinator  2014 . As shown, a service availability notification  2301  may include one or more service details entries  2361  (e.g.,  2361 A and  2361 B) describing the services available to potential customers. A given service detail entry such as entry  2361 A may include a service name  2311 A, a service description  2321 A, and pricing information  2331 A (such as recurring and non-recurring subscription rates, rates charged by the different vendors involved, rates that vary based on time of day or day of the week, rates that vary based on the geographical region where the service request originates, etc.). 
     In some embodiments a service detail entry  2361 A may also include a subscription requirement entry  2341 A, e.g., describing criteria that the customer must meet, such as a minimum bandwidth needed for service-related network data traffic between the client and the resource collection(s) such as  2020 A where the service is implemented, or a minimum time period for which the customer must subscribe to the service, and so on. In one embodiment a service detail entry  2361 A may include one or more indications of a popularity of the service, such as a satisfaction rating  2351 A, reviews, rankings and the like. Connectivity coordinator  2014  may in some embodiments be configured to allow clients to provide feedback on services such as service  2008 , and may store the feedback in its database  2015  together with other service details that may be used in the various interactions between the clients and the coordinator, for example to send satisfaction ratings  2351  to potential clients. 
       FIG.  24    illustrates an example of constituent elements of a service selection notification  2451  that may be sent by a client to a connectivity coordinator  2014 , according to at least some embodiments. Such a notification may serve as a subscription request in which the client indicates the service it wishes to utilize via its dedicated physical link  2049 . The service selection notification  2451  may also provide information about a logically-isolated path or connection the subscribing client may wish to use for the service. As shown, a service selection notification  2451  may include an identification of the selected service  2405 , payment details  2410  (e.g., details of credit cards or other sources from which payments for the services are to be made), and logical connection information  2420 . The logical connection information  2420  may include a name or identifier of a previously established logically-isolated path similar to paths  752 A and  752 B of  FIG.  7    in one embodiment. In another embodiment, the logical connection information  2410  may include elements similar to those shown in  FIG.  5   , such as a VLAN tag, a BGP ASN, network prefixes, pairing information, and/or gateway information for the logically-isolated connection over which the client wishes to transmit and receive network traffic for the subscribed service. In one implementation, a service selection notification  2451  including details  2420  of a logical connection may serve as a request to the connectivity coordinator  2048  to establish a new logical connection over the requesting client&#39;s direct link  2049 B—e.g., the connectivity coordinator  2014  may perform some actions (such as routing changes) responsive to the service selection information  2451  that are similar to the actions taken in response to isolation request  551  of  FIG.  5   . In embodiments where a client requests that a particular logically-isolated path or connection is to be used for its subscription-related traffic, the connectivity coordinator  2014  may perform one or more configuration operations to enable the traffic to flow as desired over the logically-isolated path or connection. In some implementations the subscribing client may identify which logically-isolated path(s) are to be used for a given subscription using a separate notification distinct from the service selection notification. 
     In one embodiment, connectivity coordinator  2014  may be operable to verify with a service-providing client (such as Client A of  FIG.  20   ) whether a subscription request is acceptable, e.g., before making any configuration changes that may enable traffic of such a subscription to flow.  FIG.  25    illustrates an example of constituent elements of a subscription verification request  2551  that may be sent by the connectivity coordinator  2014  to a service-providing client, according to at least some embodiments. The subscription verification request  2551  may include details  2505  of the requested subscription and/or configuration change information  2510  indicating some of the changes that the coordinator  2014  intends to put into effect if the subscription request is acceptable. Subscription details  2505  may include for example an identification of the subscribing client, payment information from the client, the number of slots that the subscription may take up, and so on. Configuration change information  2510  may include for example routing-related changes that the coordinator intends to make, and in some cases an indication of how the new subscription might impact the total bandwidth or other resources allocated to the service-providing client. A subscription verification request  2551  may be communicated via the interface implemented by the connectivity coordinator  2014  for marketplace-related functions in some embodiments (e.g., by updates to a web page listing information on pending subscription requests), and may be transmitted using other mechanisms such as e-mail in other embodiments. In response to a subscription verification request  2551 , the service-providing client may transmit a subscription approval message to the connectivity coordinator  2014  if the subscription is acceptable, and a rejection notice if the subscription is unacceptable. If the subscription is approved, the connectivity coordinator  2014  may implement the configuration changes corresponding to the subscription; if the subscription is rejected, the connectivity coordinator may inform the subscribing client of the rejection. In some embodiments a subscription verification request  2551  may be sent to the service-providing client before a service availability notification  2301  is sent to a potential customer of the service, e.g., the connectivity coordinator  2014  may wish to have potential subscriptions pre-approved before inviting a new customer to subscribe to a service. 
     Example Web Interface for Service Marketplace Operations 
       FIG.  26    is an illustration of a portion of an exemplary web-based interface that may be provided for marketplace related communications such as service advertisements, according to some embodiments. Web page  2600  may be used by service-providing clients such as Client A of  FIG.  20    to provide information about the service they are making available to other clients of provider network  2005  that have direct physical links  2049  linking their client networks to the provider network. As shown, the web-based interface may comprise several form fields that may be presented to the client by connectivity coordinator  2014 . The web page may include a welcome message area  2603 , and form fields  2605  for the clients to specify the name and description for the service they wish to advertise. In some embodiments where for example the service-providing client may wish to provide additional information about the service, such as documentation, reviews and the like, a form field  2605  may include an area to provide links to the additional information. 
     In fields  2607 , the client may indicate pricing information for the service, including for example a flat rate that may be charged regardless of the amount of network traffic that occurs on behalf of the service, and a variable rate that may be charged as a function of the amount of traffic. Additional or advanced pricing options may be specified as well in some implementations using the advanced pricing options section shown in  FIG.  26   , such as different recurring and non-recurring rates that may be charged at different times of day, on business days versus weekdays, and so on. Customer requirements for the service, such as browser software versions, bandwidth requirements and the like may be specified in fields  2611 . In embodiments where the service-providing client uses a slot-based system to indicate the available capacity for new subscribers, slot information  2613  may be provided via a form field as well. Distribution options  2614  for the service advertisement, e.g., whether the advertisement should be propagated without waiting for discovery requests may be selectable in some implementations. The submit button  2615  may be used to submit the completed service advertisement form to the connectivity coordinator  2014 . In some embodiments one or more of the form fields may be populated with the help of drop-down menus that allow the client to select from among several choices available, and default values may be provided for some form fields. Web pages similar to web page  2600  may be used for other types of marketplace-related communications between clients and the connectivity coordinator, such as discovery requests, subscription requests, and the like. 
     In one embodiment, the submission of such a form  2600  may result in the invocation of one or more APIs at the connectivity coordinator  2014  similar to APIs API-1 through API-18 and API 21 through API-25 described earlier. Example API invocations for marketplace-related operations may include the following: 
     [API-31] AdvertisementStatus status=advertiseService(CustomerID customerId, AdvertisedServiceInfo advertisedServiceInfo);
 
The advertiseService API may be used by a service-providing client such as Client A of  FIG.  20    to send information about an advertised service, encapsulated within an AdvertisedServiceInfo object, to the connectivity provider.
 
[API-32] ServiceList sList=discoverAvailableServices(CustomerID customerId, ServiceSelectionCriteria serviceSelectionCriteria, NotificationSettings nSettings);
 
The discoverAvailableServices API may be used by a potential customer to discover information about available services that meet specified service selection criteria. A list of services that match the criteria may be specified in the returned ServiceList object.
 
[API-33] RequestStatus status=subscribeToService(CustomerID custId, ServiceID serviceId, LogicalConnectionInfo logConnInfo, BillingInfo billingInfo);
 
The subscribeToService API may be used to specify the service to which a client such as Client B wishes to subscribe over a logically-isolated connection specified using the LogicalConnectionInfo object.
 
[API-34] RequestStatus approvalStatus=approveSubscription(SubscriptionInfo sInfo);
 
The approveSubscription API may be used by the connectivity coordinator to verify whether a service-providing client wishes to accept a requested subscription described in the SubscriptionInfo object.
 
     As noted above, in some embodiments connectivity coordinator  2014  may allow clients to extend or customize the interface, e.g., by introducing some level of branding to the information seen by prospective customers regarding a service. In some implementations multiple layers of interfaces may be supported, allowing clients to request some connectivity-related operations using a web interface, for example, and to perform or request other operations using an API. 
     Methods for Service Marketplace Operations 
       FIG.  27    is a flowchart of a method for enabling marketplace operations to which access is configurable via direct physical links, according to at least some embodiments. As shown in element  2700  of  FIG.  27   , the method comprises implementing an interface that defines a set of connectivity operations made available to clients of a provider network  2005  by a connectivity coordinator  2014 . The interface may comprise an API, a command-line interface, a web-based interface, some other GUI, or any other programmatic interface in various embodiments. As shown in element  2705 , the method may include waiting for a marketplace-related request received in accordance with the interface. Depending on the type of request, one or more operations may be performed as part of the method. For example, if the request is a service advertisement request (element  2710 ), information on the newly-advertised service may be stored as shown in element  2715 , e.g., in a repository such as database  2015 . In some embodiments, information on the newly advertised service may be propagated to potential customers of the service, either as soon as the advertisement is requested, or according to a schedule requested by the advertiser or the potential customers. A notification of the availability of an advertised service may also be transmitted in accordance with the interface. 
     If a service discovery request is received (element  2720 ), indicating that the requester wishes to learn about services accessible through their direct path  2049  to the provider network, a notification that enumerates available services that meet the criteria specified in the request may be transmitted in accordance with the interface (element  2725 ). In response to the notification, or upon learning about available services based on some other interaction such as a propagated service advertisement, a client may submit a subscription request (element  2730 ) using the interface, identifying the service to which access is requested. The method may, as indicated in element  2735 , further include performing or initiating one or more configuration changes in response to a subscription request (e.g., routing changes at endpoint routers) that may be needed to enable access to the service from the subscriber&#39;s client network. In some embodiments the service-providing client may be sent a subscription verification request to check that the new subscription is still acceptable, prior to the configuration changes. 
     The method may also comprise operations performed responsive to other types of marketplace-related requests. For example, as shown in elements  2740  and  2750 , in some embodiments, clients may submit requests to unsubscribe from a service (element  2740 ), or queries (element  2750 ) e.g., regarding their subscriptions or regarding other services). In response to an unsubscribe request, the method may comprise performing one or more configuration operations to disable connectivity between the client network and the resource collection where the service is implemented (element  2745  of  FIG.  27   ). The configuration changes may include routing changes at one or more routers or other network devices, as well as changes to subscription slot availability records, for example. In response to queries regarding client subscriptions, service usage and the like, a query response may be generated (element  2755 ), e.g., by consulting a database  2015  in which marketplace related data is stored, and the response may be transmitted back to the requesting client in accordance with the interface implemented by the connectivity coordinator  2014 . After a requested operation is completed, the method may comprise resuming waiting for the next marketplace related request. 
     As noted earlier, in some embodiments, information regarding the ability of a service-providing client (such as Client A of  FIG.  20   ) to accept new subscriptions may be maintained using a subscription slots mechanism.  FIG.  28    is a flowchart of a method comprising using subscription slots to manage incoming subscription requests, according to at least some embodiments. As shown in element  2800 , the method may comprise implementing an interface for connectivity-related services, and waiting for the next marketplace-related connectivity request (element  2805 ). In response to receiving new or updated slots information from a service-providing client (element  2810 ), the method may comprise storing the slots information in a database or persistent repository (element  2815 ). Subscription slots information may comprise, for example, an indication of how many subscribers the service-providing client is currently capable of serving, or how many distinct network ports or connections are available for subscriptions. In some implementations the slots information may include, for each slot, one or more IP addresses and/or TCP/IP port numbers from which the service may be accessed for the customer to whom that slot is allocated. In one implementation, a given slot may have additional information such as service-level characteristics associated with the corresponding subscription—e.g., a list of 10 open slots may include 3 slots for 10 GB of service related traffic per month and 7 slots for 1 GB traffic each. The service-providing client may in some embodiments use the interface provided by the connectivity provider to provide updates to slots information as subscribers are added or removed. 
     In element  2820 , a new subscription request may be received at the connectivity coordinator in accordance with the interface. In response, the coordinator may determine whether a free slot is available (element  2830 ). If no slot is available, the subscription request may be rejected (element  2835 ). If a slot is available, the configuration changes needed to enable network traffic for the service between the subscriber&#39;s client network and the resources used for the service may be implemented (element  2840 ), and the slots information may be updated (e.g., by allocating one or more of the slots to the new subscriber). In some embodiments, the connectivity coordinator may be configured to monitor the number of slots available, and if the number of slots reaches some threshold (e.g., if 90% of the slots known to it are filled), notify the service-providing client, as shown in elements  2845  and  2850 . The service-providing client may thus be made aware that it may soon need to increase the resources dedicated to providing the service, if new customers are to be accommodated. 
     Remote Connectivity Services Across Geographical Region Boundaries 
     In some cases an operator of a provider network may have facilities, including data centers, set up in multiple geographical regions. For example, one set of data centers may be established near the east coast of the continental United States, another set near the west coast, a third set in Europe, and a fourth set in Asia. For administrative as well as technical reasons, such a globally distributed provider network may be managed as a set of geographical zones, with each zone corresponding to a set of data centers and other facilities (such as the router co-location facilities  150  of  FIG.  1   ) that are located near each other. The resource collections within a given geographical zone may be operated somewhat independently of those in other zones (e.g., different zones may have their own pricing policies, legal policies based on the region&#39;s government regulations, and the like) and yet may be reachable from other zones via private dedicated network paths that are also managed by the provider network&#39;s operator. Multiple geographical zones may help the operator of the provider network serve customers distributed across the world, and may enable functionality such as disaster recovery or remote replication that may not be easily accomplished without geographical diversification. In addition, in some cases such geographical diversification may permit the operator of the provider network to allow clients to benefit from pricing and technology variations across the different regions. In some embodiments, for example, a client that has established a direct physical link (similar to cross-network connection  191  of  FIG.  1   ) to a provider network in one geographical zone may be able to access resources in other geographical zones using that same physical link, thus obtaining the benefits of having such a direct link without having to establish additional similar links in the other zones. 
       FIG.  29    illustrates an example of a system  2900  with a provider network  2905  comprising a plurality of geographical zones, according to at least some embodiments. In the illustrated embodiment, provider network  2905  includes geographical zones  2906 A and  2906 B. Geographical zone  2906 A is designated as the “local” zone in the following description; it is the zone within which a client has established a direct dedicated physical link  2949 . Geographical zone  2906 B is designated the “remote” zone. The client in the illustrated embodiment operates a distributed client network, comprising a local client network component  2962 A and a remote client network component  2962 B that may be linked via paths external to the provider network (e.g., via elements of the public Internet and/or client-managed private paths), such as path  2959 . The client may have established the direct link  2949 , e.g., with the help of a connectivity coordinator  2914  using techniques similar to those described earlier in conjunction with the description of  FIG.  1    or  FIG.  11   , to set up a logically-isolated path  2910 A between its local client network  2962 A and a local resource collection  2920 A via an endpoint router  2917 . 
     Connectivity provider  2914  may be operable to implement a programmable interface (which may enhance or extend the functionality of the interfaces described earlier of coordinator  114  of  FIG.  1   , coordinator  1114  of  FIG.  11   , and/or coordinator  2014  of  FIG.  20   ) defining connectivity services for remote geographical zones such as zone  2906 B in the illustrated embodiment. For example, in response to a connectivity request formatted according to the interface to establish a logically isolated network path to remote resource collection  2920 B, connectivity coordinator  2914  may perform one or more configuration operations to enable traffic to flow from the local client devices  2948 A to remote resource collection  2920 B over path  2910 B using the dedicated physical network link  2949 . The configuration operations may include, for example, routing changes at endpoint router  2917  and/or changes at other networking devices within inter-region paths  2990  of the provider network. 
     In some embodiments, the establishment of logically-isolated oath  2910 B may require the requesting client to communicate with a metadata target  2932  in the remote zone  2906 B. For example, in response to the connectivity request in such an embodiment, the connectivity coordinator  2914  may send connectivity metadata to the requesting client together with instructions to transmit the connectivity metadata to the metadata target  2932  over an alternate network path outside the provider network. The connectivity metadata may in some embodiments comprise information on some of the possible configuration changes that may be proposed by connectivity coordinator  2914 , and may also include information about the requesting client or client devices. The connectivity metadata may be encoded or encrypted into a format that cannot be parsed by the client in some embodiments, e.g., to prevent the client from deliberately or accidentally corrupting or modifying the metadata. Such a technique may be used, for example, in a provider network  2905  that is configured to minimize control traffic or network administration traffic across its geographical zone boundaries, especially control traffic initiated in response to some types of client requests. Minimizing cross-zone control traffic in this way may help reduce the chances that the effects of a failure, misconfiguration or network intrusion within one geographical zone spread across multiple zones, and may thereby increase the reliability and availability of the provider network as a whole. The client may transmit the connectivity metadata from its local client network  2962 A via external path  2959  to its remote client network  2962 B, and from remote client network  2962 B to the metadata target  2932  via path  2969  in the illustrated embodiment. The metadata target  2932  may process or validate the connectivity metadata in some embodiments, and send an indication to the connectivity coordinator  2914  (using any appropriate paths comprising elements internal to or external from the provider network) that the metadata has been received and processed as requested. Upon receiving such an indication, the connectivity coordinator may in such an embodiment proceed to make the configuration changes needed to establish the logically-isolated path  2910 B. The metadata target  2932  may comprise various types of devices in different embodiments, such as for example a router, a gateway, or some other device capable of performing network administration functions. In some embodiments the metadata target  2932  may comprise a remote component of the connectivity coordinator  2914 . 
     In addition to responding to connectivity requests for paths to remote zones, in some embodiments connectivity coordinator  2914  may also provide other services related to remote zones. For example, the connectivity coordinator  2914  may respond to a client query via the interface asking for an enumeration of remote resource collections to which paths can be set up by that client, a client query asking for performance metrics or status of a logically-isolated path to a remote resource collection, and so on. The connectivity coordinator  2914  may store connectivity-related information in a database  2915  in some embodiments, which may be used to provide responses to such client queries. Clients may also use the interface to disable or terminate logical paths such as path  2910 B, to modify the characteristics (e.g., the maximum allowed traffic rate) of an existing logically-isolated path, to provide payment-related information for the paths, to identify services (similar to service  2008  of  FIG.  20   ) that may be implemented in a remote zone, and so on. Pricing information for the remote connectivity services (such as rates for traffic that stays within a given zone, and rates for traffic that crosses zone boundaries) may also be provided via the interface. Pricing for traffic within one zone (e.g., the local zone  2906 A) may differ from pricing from traffic within a different zone (e.g., remote zone  2906 B) in some embodiments, and pricing for traffic that moves from one zone to another may be different from intra-zone pricing for either zone. The pricing information provided via the interface in some embodiments may include pricing indicators that depend on the amount of network traffic generated (e.g., based on the number of megabytes of network traffic over a given time period), and/or on the distance that traffic is transmitted. In one embodiment, service characteristics such as expected response times or throughputs may differ from one zone to another, and the interface may be used to provide information on such service variations as well: for example, the expected response times may be higher for requests that cross zone boundaries than for requests are serviced without crossing zone boundaries. In some embodiments access policies may be associated with various local and remote resource collections  2920  and/or the services implemented therein, which may govern who is allowed to access the resource collection or service, or from where such access is permitted. In such embodiments, before responding to a connectivity request or providing any connectivity-related notifications or responses, the connectivity coordinator  2914  may verify whether the action it is taking is in compliance with the applicable access policy or policies. Access policies associated with the resource collections  2920  and/or associated services may, in some implementations, be stored in the database  2915 . The interface may comprise any combination of an application programming interface, a command-line interface, a GUI, and/or a web interface in different embodiments. 
     Examples of Client-Coordinator Interactions for Remote Connectivity Operations 
     In some environments, clients may have multiple resource collections allocated for their use in various geographical zones, and it may not be clear to the client how many (or exactly which) remote resource collections may be reachable via new logically-isolated paths over a given direct physical link.  FIG.  30    illustrates examples of constituent elements of a remote resource collection enumeration request  3051  that may be sent to connectivity coordinator  2914  by a client using the interface provided by the connectivity coordinator, according to at least some embodiments. Such a request may be sent by the client to identify the specific resource collections in remote zones to which it may be possible to establish new logically-isolated paths using an existing dedicated physical link such as link  2949  of  FIG.  29   . As shown, the request comprises a client identifier  3060  of the requesting client, zone information  3061  indicating the geographical zones to which logically-isolated paths may be desired, and physical link identification information  3063  indicating the direct link or links to be used for the paths. In some embodiments the request may include only the client identification  3060  and the zone information  3061 , and the connectivity coordinator  2914  may be responsible for identifying both the remote resource collections and the direct physical links that have already been set up on behalf of the client. 
       FIG.  31    illustrates examples of constituent elements of a remote resource collection enumeration response  3151  that may be sent by connectivity coordinator  2914  using the interface to a client from which a request similar to request  3051  was received, according to at least some embodiments. Such a response may include a list of resource collection details records such as  3171 A and  3171 B which the connectivity coordinator  2914  may have retrieved from its connectivity database  2915  in some embodiments. Each details record  3171  may comprise an identification  3160  of a resource collection within a corresponding geographical zone  3161  to which a new logically-isolated path may be established over an existing physical link identified by physical link information  3162 . In addition, the response  3151  may include pricing-related information  3163  for each potential logically-isolated path in one embodiment. Pricing details may include different rates for different time periods—e.g., in an environment where the local zone and the remote zone are in different time zones, one rate may be quoted for inter-zone traffic during 8 am to 6 pm of each business day in the local zone, and another rate may be quoted for inter-zone traffic during Sam to 6 pm of the remote zone&#39;s business day. Pricing information  3163  may include fixed fees (e.g., for establishing the logically-isolated paths) and traffic-based fees (e.g., proportional to the amount of traffic transmitted or the number of service requests made). In some embodiments clients may also be charged based on their use of additional services that may be provided within the provider network, such as hardware or software load balancing, wide area network (WAN) scaling, and the like. In such embodiments pricing information  3163  may include indicators of the pricing for such services. 
       FIG.  32    illustrates examples of constituent elements of a remote logical connection request  3251  that may be sent by a client to connectivity coordinator  2914  using the interface, according to at least some embodiments. In embodiments where a client sends a remote resource collection enumeration request such as request  3051  to a connectivity coordinator to find potential remote resource collections, request  3251  may be sent after the remote resource collections have been enumerated and the client has selected a particular remote resource collection. In other embodiments a client may not need to request an enumeration of remote resource collections (e.g., if the client already knows which remote resource collection to connect to, or has only one remote resource collection), and in such cases a remote logical connection request  3251  may be sent without the types of communications shown in  FIGS.  30  and  31   . The remote logical connection request  3251  may include client identification  3262 , the remote resource collection identification  3260 , zone information  3261  for the remote resource collection, information  3262  identifying the physical link (similar to link  2949  of  FIG.  29   ) to be used, and logical connection information  3265  in some embodiments. Logical connection information  3265  may in turn comprise any of a number of elements similar to those shown in  FIG.  5   , such as a connection identifier  482 , VLAN tag  501 , BGP ASN information  511 , network prefixes  521 , pairing information  531 , and virtual private gateway information  541 , that may be useful in establishing the requested logically-isolated path. 
     Upon receiving a remote logical connection request  3251 , in some embodiments connectivity coordinator  2914  may perform the configuration change or changes (such as routing changes at endpoint router  2917  and/or configuration changes at other network devices managing traffic flow over inter-regional paths  2990 ) needed to enable traffic to flow over the requested logically-isolated path. In other embodiments the provider network  2905  may implement policies that require the requesting client to perform an additional step of transmitting metadata for the requested logical connection to a target address, before the configuration changes are made.  FIG.  33    illustrates examples of constituent elements of a metadata transmission request  3351  that may be sent by the connectivity coordinator  2914  to a client via the interface, according to at least some such embodiments. The metadata transmission request  3351  may comprise identification information  3360  for the resource collection to which a new logically-isolated path was requested by the client, physical link information  3363  identifying the direct physical link to be used, connectivity metadata  3364  and instructions  3365  for transmitting the connectivity metadata. The instructions may, for example, comprise an IP address or addresses in the remote zone to which the client is requested to transmit the metadata  3364 , and/or steps to be followed during the transmission—e.g., the equivalent of “save the metadata as a file and forward it as an email attachment”, or “open a web page at this host and port, authenticate yourself using your user ID, and paste the metadata in the form field on the page”. In some embodiments the metadata  3364  may be encoded or encrypted, e.g., using a digital signature mechanism in which the connectivity coordinator and the metadata target device participate, so that its contents are not easily modifiable or corruptible by the client. As described earlier, such a step of requesting a client to transmit connectivity metadata to a destination in the remote zone via a path outside the provider network may be implemented to reduce the control traffic across geographical zones in some embodiments, and may help enhance the reliability and fault-tolerance of the provider network. 
     In an embodiment in which a metadata transmission request  3351  is sent to a client, the connectivity coordinator  2914  may then wait for an acknowledgement from the metadata target device to which the client is requested to send the metadata. Such an acknowledgment may be transmitted across paths external to the provider network in some embodiments, and within the provider network in other embodiments. When an acknowledgment from the metadata target device is received, indicating that the metadata was transmitted by the client as per the instructions  3365  and was found to be valid, the connectivity coordinator  2914  may perform the configuration changes needed to establish the desired logically-isolated connection. In some embodiments the metadata may be used by one or more devices within the remote zone (including, for example, the metadata target device) to perform configuration changes needed for the logical connection within the remote zone, and the connectivity coordinator  2914  may perform configuration changes needed within the local zone. In one embodiment, portions of the functionality provided by connectivity coordinator  2914  may be implemented within each zone, and the target metadata device may comprise a remote component of the connectivity coordinator. After the desired connectivity has been established, in one embodiment the connectivity coordinator may send a confirmation message to the client, similar to the confirmation message  651  of  FIG.  6   . 
     Example Web Interface for Remote Logical Connections 
       FIG.  34    is an illustration of a portion of an exemplary web-based interface that may be provided to allow a client to request the establishment of a logically-isolated path to a remote resource collection, according to some embodiments. As shown, form fields included within a web page  3400  may be used by clients to provide the information needed to set up such a path. The web page may include a welcome message area  3403 , and form field  3405  for the client identifier of the requesting client. The remote resource collection to which the logically isolated path is desired may be specified via form field  3407 . The remote zone may be specified via field  3409 , and the direct physical link to be used may be identified via filed  3411 . 
     Additional details about the desired logically-isolated path, such as a VLAN tag, a BGP ASN, network prefixes, pairing information, and gateway information, may be specified via form fields  3413 . The submit button  3415  may be used to submit the completed request for the remote logical connection to the connectivity coordinator  2914 . In some embodiments one or more of the form fields may be populated with the help of drop-down menus that allow the client to select from among several choices available, and default values may be provided for some form fields. Web pages similar to web page  3400  may be used for other types of remote connectivity-related communications between clients and the connectivity coordinator as well, such as enumeration requests for identifying remote resource collections, modifications to existing logical connections, queries, and connection disablement or termination. 
     In one embodiment, the submission of such a form  3400  may result in the invocation of one or more APIs at the connectivity coordinator  2914  similar to APIs API-1 through API-18, API 21 through API-25, and API-31 through API-34 described earlier. Example API invocations for operations related to remote logical connections may include the following in one implementation: 
     [API-41] ResourceCollectionList rsList=findRemoteResourceCollections(CustomerID customerId, ZoneInfo zoneInfo, ConnectionId connectionId);
 
The findRemoteResourceCollections API may be used to obtain an enumeration or list of remote resource collections in specified zones to which connectivity may be enabled using a physical link identified via connectionId.
 
[API-42] LogicalRequestId logicalRequestId=set UpRemoteLogicalConnection(ConnectionId connectionId, RemoteLogicalConnectionParameters lcParameters);
 
The setUpRemoteLogicalConnection API may be used to request that a logically isolated network path be set up using a previously established physical connection and a set of logical connection properties encapsulated in a RemoteLogicalConnectionParameters object.
 
[API-43] RemoteLogicalConnectionInfo logicalConnectionInfo=getRemoteLogicalConnectionInfo(LogicalConnectionId logicalConnectionId);
 
The getRemoteLogicalConnectionInfo API may be used to obtain the properties and status of the remote logical connection, including such properties as the VLAN tag being used and/or other routing-related information associated with the logical connection.
 
[API-44] RemoteLogicalConnectionRequestStatus modificationStatus=modifyRemoteLogicalConnection(LogicalConnectionId logicalConnectionId, LogicalConnectionModificationInfo modificationInfo);
 
The modifyRemoteLogicalConnection API may be used to request changes to an existing remote logical connection—e.g., to modify the set of network prefixes associated with it.
 
[API-45] RemoteLogicalConnectionRequestStatus disableLogicalConnectionStatus=disableRemoteLogicalConnection(LogicalConnectionId connectionId);
 
The disableRemoteLogicalConnection API may be used to request that an existing remote logical connection be disabled, i.e., that no traffic be allowed to flow through the logically-isolated path associated with the logical connection.
 
[API-46] RemoteLogicalConnectionRequestStatus enableLogicalConnectionStatus=enableRemoteLogicalConnection(LogicalConnectionId connectionId);
 
The enableRemoteLogicalConnection API may be used to request that an existing (e.g., currently disabled) remote logical connection be enabled.
 
[API-47] RemoteLogicalConnectionRequestStatus deleteLogicalConnectionStatus=deleteRemoteLogicalConnection(LogicalConnectionId connectionId);
 
The deleteRemoteLogicalConnection API may be used to request that a remote logical connection be removed permanently.
 
     In some implementations multiple layers of interfaces may be supported, allowing clients to request some connectivity-related operations using a web interface, for example, and to perform or request other operations using an API. Customized versions of portions of the interface may be provided in some implementations, e.g. web pages may be translated into the local language for each zone. 
     Methods for Remote Connectivity Operations 
       FIG.  35    is a flowchart of a method for providing connectivity services across geographical zones of a provider network, according to at least some embodiments. As shown in element  3500  of  FIG.  35   , the method may comprise implementing a programmatic interface that defines a set of connectivity operations made available to clients of a provider network  2905  by a connectivity coordinator  2914 . The interface may comprise an API, a command-line interface, a web-based interface, some other GUI, or any other programmatic interface, for example. As shown in element  3505 , the method may include waiting for a remote connectivity-related request received in accordance with the interface. Depending on the type of request, one or more operations may be performed as part of the method. For example, if the request is a query related to an existing remote logical connection or a remote resource collection (element  3510 ), a response to the query may be generated (element  3515 ), e.g., by consulting database  2915 , and transmitted to the requester. In response to a query (such as the request  3051  of  FIG.  30   ) requesting an enumeration of remote resource collections to which logically isolated paths may be configurable, a list of such resource collections may be provided to the requester, together with information such as connectivity pricing rates in some embodiments. If a request to establish a remote logical connection is received (element  3520 ), and the connectivity coordinator is configured to use the technique described above of requesting the client to transmit connectivity metadata to a designated address within the remote zone (as determined in element  3525 ), the connectivity coordinator  2914  may send the metadata and instructions (element  3526 ) to the requesting client. After the metadata has been transmitted in accordance with the instructions, an acknowledgement of the metadata transfer may be received from the remote zone by the connectivity coordinator (element  3527 ). The configuration operations to enable traffic to flow over the requested logically-isolated path may then be performed (element  3528 ). In embodiments where connectivity metadata transfer by the client is not required, the connectivity coordinator  2914  may perform the configuration operations as indicated in element  3528  in response to receiving the request as shown in element  3520 . The configuration operations may for example include routing changes at endpoint routers  2917  or other devices involved in administering inter-region paths  2990  of the provider network. 
     If a request to disable or terminate a logically isolated path to a remote resource collection is received (element  3530 ), the appropriate configuration changes may be performed (element  3535 ) to disable further traffic via the path. In some implementations, clients may issue requests via the interface to modify one or more properties of an existing remote logical connection (element  3540 ), such as the maximum traffic rate supported, and in response the connectivity coordinator may modify the properties as requested (element  3545 ). Upon completing the operations responsive to a given request, the method may comprise resuming waiting for the next client request. In some embodiments multiple requests may be handled in parallel. 
     Example Use Cases 
     The techniques described above of providing easy-to-use interfaces for dedicated connectivity operations may be used in a variety of environments. For example, if the provider network is expanding quickly across new geographical regions where the reliability, performance and/or security of publicly available networking facilities is limited, more and more clients may wish to utilize dedicated connectivity, especially if it is provided at a reasonable price point. In addition, in cases where a provider network operator may already provide a set of interfaces for managing computation and/or storage resources (such as resource collections  120  of  FIG.  1   ) that are currently accessed via shared (non-dedicated) paths, the provision of additional interfaces to manage dedicated connectivity options may significantly increase the adoption rate of the dedicated connectivity services in which the operator has invested. 
     Illustrative Computer System 
     In at least some embodiments, a server that implements a portion or all of one or more of the technologies described herein, including the techniques to implement an interface that defines various connectivity services and operations, and to receive and respond to various types of connectivity requests via the interface, may include a general-purpose computer system that includes or is configured to access one or more computer-accessible media, such as computer system  6000  illustrated in  FIG.  36   . In the illustrated embodiment, computer system  6000  includes one or more processors  6010  coupled to a system memory  6020  via an input/output (I/O) interface  6030 . Computer system  6000  further includes a network interface  6040  coupled to I/O interface  6030 . 
     In various embodiments, computer system  6000  may be a uniprocessor system including one processor  6010 , or a multiprocessor system including several processors  6010  (e.g., two, four, eight, or another suitable number). Processors  6010  may be any suitable processors capable of executing instructions. For example, in various embodiments, processors  6010  may be general-purpose or embedded processors implementing any of a variety of instruction set architectures (ISAs), such as the x86, PowerPC, SPARC, or MIPS ISAs, or any other suitable ISA. In multiprocessor systems, each of processors  6010  may commonly, but not necessarily, implement the same ISA. 
     System memory  6020  may be configured to store instructions and data accessible by processor(s)  6010 . In various embodiments, system memory  6020  may be implemented using any suitable memory technology, such as static random access memory (SRAM), synchronous dynamic RAM (SDRAM), nonvolatile/Flash-type memory, or any other type of memory. In the illustrated embodiment, program instructions and data implementing one or more desired functions, such as those methods, techniques, and data described above, are shown stored within system memory  6020  as code  6025  and data  6026 . 
     In one embodiment, I/O interface  6030  may be configured to coordinate I/O traffic between processor  6010 , system memory  6020 , and any peripheral devices in the device, including network interface  6040  or other peripheral interfaces. In some embodiments, I/O interface  6030  may perform any necessary protocol, timing or other data transformations to convert data signals from one component (e.g., system memory  6020 ) into a format suitable for use by another component (e.g., processor  6010 ). In some embodiments, I/O interface  6030  may include support for devices attached through various types of peripheral buses, such as a variant of the Peripheral Component Interconnect (PCI) bus standard or the Universal Serial Bus (USB) standard, for example. In some embodiments, the function of I/O interface  6030  may be split into two or more separate components, such as a north bridge and a south bridge, for example. Also, in some embodiments some or all of the functionality of I/O interface  6030 , such as an interface to system memory  6020 , may be incorporated directly into processor  6010 . 
     Network interface  6040  may be configured to allow data to be exchanged between computer system  6000  and other devices  6060  attached to a network or networks  6050 , such as other computer systems or devices as illustrated in  FIGS.  1  through  35   , for example. In various embodiments, network interface  6040  may support communication via any suitable wired or wireless general data networks, such as types of Ethernet network, for example. Additionally, network interface  6040  may support communication via telecommunications/telephony networks such as analog voice networks or digital fiber communications networks, via storage area networks such as Fibre Channel SANs, or via any other suitable type of network and/or protocol. 
     In some embodiments, system memory  6020  may be one embodiment of a computer-accessible medium configured to store program instructions and data as described above for  FIGS.  1  through  35    for implementing embodiments of methods and apparatus for interfaces to manage direct network peerings. However, in other embodiments, program instructions and/or data may be received, sent or stored upon different types of computer-accessible media. Generally speaking, a computer-accessible medium may include non-transitory storage media or memory media such as magnetic or optical media, e.g., disk or DVD/CD coupled to computer system  6000  via I/O interface  6030 . A non-transitory computer-accessible storage medium may also include any volatile or non-volatile media such as RAM (e.g. SDRAM, DDR SDRAM, RDRAM, SRAM, etc.), ROM, etc, that may be included in some embodiments of computer system  6000  as system memory  6020  or another type of memory. Further, a computer-accessible medium may include transmission media or signals such as electrical, electromagnetic, or digital signals, conveyed via a communication medium such as a network and/or a wireless link, such as may be implemented via network interface  6040 . 
     CONCLUSION 
     Various embodiments may further include receiving, sending or storing instructions and/or data implemented in accordance with the foregoing description upon a computer-accessible medium. Generally speaking, a computer-accessible medium may include storage media or memory media such as magnetic or optical media, e.g., disk or DVD/CD-ROM, volatile or non-volatile media such as RAM (e.g. SDRAM, DDR, RDRAM, SRAM, etc.), ROM, etc, as well as transmission media or signals such as electrical, electromagnetic, or digital signals, conveyed via a communication medium such as network and/or a wireless link. 
     The various methods as illustrated in the Figures and described herein represent exemplary embodiments of methods. The methods may be implemented in software, hardware, or a combination thereof. The order of method may be changed, and various elements may be added, reordered, combined, omitted, modified, etc. 
     Various modifications and changes may be made as would be obvious to a person skilled in the art having the benefit of this disclosure. It is intended to embrace all such modifications and changes and, accordingly, the above description to be regarded in an illustrative rather than a restrictive sense.