Patent Publication Number: US-7715429-B2

Title: Interconnect system for supply chain management of virtual private network services

Description:
FIELD OF INVENTION 
   The present invention generally relates to the field of network grid architecture. More particularly, the present invention relates to the architecture and its configuration in delivering managed virtual private networks (VPNs) and VPN services involving multiple carriers. 
   BACKGROUND OF INVENTION 
   As more and more people rely on the ability to communicate data electronically, there is a growing dependency by firms and organizations on the computer networks used to connect its users to each other. For many businesses that have geographically distributed employees, customers and strategic partners, integrating and on-going management of the corporation&#39;s computer networks is a major and increasing challenge. 
   In general, global businesses and organizations have disparate requirements for data network services. There are several approaches to solving a business&#39; network service requirements. One approach is to interconnect a company&#39;s offices or various site locations with dedicated or private communication connections via a wide area network (WAN). 
   An advantage of this traditional approach to building a customized private network is that it is generally owned and managed by the corporation; management of the network along with control of computing resources, is centralized. Another advantage is improved security of the network against unauthorized access. 
   However, a major disadvantage of a corporate-owned and controlled private network is the extremely high total cost of procurement, design, implementation, operations, management, skill retention, and facilities related to private networks. Also, private corporate networks are oftentimes underused as the dedicated resources must be configured to handle the peak capacity requirements of the business. 
   In an attempt to reduce costs and enhance their competitiveness, some companies chose to deploy some business applications over the public Internet, a second approach to solving a business&#39; network service requirements. In other words, rather than undergoing the considerable expense of constructing a private network of dedicated communication lines, some companies opt to employ the Internet to facilitate communication between various remote sites. 
   An advantage of using the Internet as a transport mechanism is the Internet&#39;s ubiquity; Internet access is worldwide. It is also convenient. However, a major disadvantage is that the Internet is a public network. Data propagation is indeterminate, security is relatively low and performance is not guaranteed. Electronic communications are susceptible to interception, modification and replication by third parties, essentially compromising proprietary and confidential internal corporate communications. 
   Because the potential business related damage resulting from security breaches and unreliable performance has become such a critical factor in network services, companies often seek an alternative solution to the Internet to obtain virtual private network (VPN) services with a high degree of security and performance assurance. 
   As a practical matter, there are two approaches to providing VPN services today: “on-net” or “off-net”. These VPN services are generally a premium service offered by a service provider where a firm or business contracts with the service provider for a specified VPN service. 
   In the on-net approach, typically a service provider offers VPN service on its own network infrastructure only. An advantage of on-net service is that it does not require collaboration among multiple service providers, and generally uses standard service provider products and services only. However, a major drawback is the limited reach of a sole service provider&#39;s network. One service provider on its own often cannot offer service to corporate sites in all cases. 
   When a subscriber&#39;s requirements extend beyond the service provider&#39;s infrastructure, an off-net approach is used that sometimes employs the Internet to provide basic, easy-to-implement and easy-to-administer off-net capabilities. Alternatively, two or more service providers may collaborate which may involve some integration of transport networks, operations systems and business systems. Of course, a service provider may choose to extend its reach by building its own network to reach the off-net sites. But this often proves expensive. 
   The problem with one or more of the above-mentioned conventional approaches is difficulty of implementation. Significant time and coordination is required to arrange new service provider partnership(s), and to interconnect network(s) and/or technologies and/or configurations and/or operations systems and/or business systems. For example, a service provider must undertake to coordinate field support of off-net gateways with one or more third party groups. Additionally, the integration of operational and business systems to make the collaboration viable is complex and costly. Moreover, once set-up, the complex interconnections are difficult to change. 
   Another problem in one or more of the prior art approaches is the significant investment of financial resources. The cost of implementing and maintaining an off-net computer network, for example, is high. These high costs are compounded by the high costs for long distance charges for leased lines and switched services. In addition, the number of support staff necessary to manage these networks further increases the costs to manage them. 
   Yet another problem in one or more of the prior art approaches is non-deterministic route propagation. The route by which data communications travel from point to point over a public network, such as the Internet, can vary on a per packet basis, and is essentially indeterminate. This prevents per customer design, implementation and monitoring, essentially preventing a service being engineered to meet an individual customer&#39;s need. It also prevents differentiation between customers because per-customer state/status is not maintained throughout the network. 
   Yet another problem in one or more of the prior art approaches is unreliable network performance. There are little or no controls in the way that users use the Internet, for example. This generally means that one customer&#39;s use of the Internet may be adversely affected by another customer, for instance. 
   Yet another problem in one or more of the prior art approaches is the low level of data security. The data protocols for transmitting information over a public network, such as the Internet, are widely known. Consequently, electronic communications over the Internet are susceptible to interception. Packets can be replicated or even modified by unauthorized users. 
   Yet a further problem in one or more of the prior art approaches is significant delays in restoring service to customers. A significant number of performance-related faults occur at the interface between the off-net gateway and the off-net transport service, for instance. These problems prove very difficult to resolve and, again, the extending service provider must undertake to coordinate fault resolution with the off-net transport supplier. 
   Yet a further problem in one or more of the prior art approaches is lack of effective monitoring to determine whether one or more service providers are providing acceptable or unacceptable service. This creates a bottleneck for proper billing, settlement, fault-finding and fault resolution. 
   Yet a further problem in one or more of the prior art approaches is lack of service guarantees provided to customers. Fault resolution, a service guarantee highly valued by corporate customers, is often haphazard, without procedure, based on goodwill, and of indeterminate duration. This generally results in unacceptably long delays for VPN service to be properly restored. 
   These and other problems are shortcomings for which there is a need to overcome. 
   GLOSSARY 
   The detailed description of the present invention that follows may be easier understood by presentation of the following basic concepts about computer-to-computer communications and virtual private networks, in alphabetical order. 
   ATM (Asynchronous Transfer Mode) is a network technology capable of transmitting data, voice, audio, video, and frame relay traffic in real time. The basic unit of ATM transmission is referred to as a cell, which is a packet consisting of 5 bytes of routing information and a 48-byte payload (data). 
   Collocation Facility is best described as a secure facility where two or more service providers or disparate network fabrics may co-exist. 
   CoS (Class of Service) is a term used to refer to a category or subdivision of service, often by application type, of required quality of service performance. 
   CoS Mediation refers to the switch software that performs mediation between the different class-of-service mechanisms associated with the VPN types that it supports. This includes class-of-service mapping between two networks of the same VPN type that uses different class-of-service values. 
   EBGP (Exterior Border Gateway Protocol) is a protocol for distributing information regarding availability of the routers and gateways that interconnect networks. 
   End-to-end Service refers to the total service provided by an agreement between a subscriber and a provider. End-to-end service may comprise many network service sub-components in the context of a supply chain. 
   Frame Relay is a packet-switching protocol for use on wide area networks (WANs). Frame relay transmits variable-length packets over predetermined, set paths known as permanent virtual circuits. It is a variant of X.25 but dispenses with some of X.25&#39;s error detection and flow control for the sake of speed. 
   IPSec (Internet Protocol Security) generally refers to the security of the protocol standard within Transmission Control Protocol/Internet Protocol (TCP/IP) that governs the breakup of data messages into packets, the routing of packets from sender to destination network and station, and the re-assembly of packets into original data messages at the destination. 
   L2TP (Layer 2 Tunneling Protocol) is a set of rules or standards that governs the method of transmission of a wrapped packet. In tunneling, a packet based on one protocol is wrapped or encapsulated into a second packet based on whatever differing protocol is needed in order for it to travel over an intermediary network. This method of packet transmission is used to avoid protocol restrictions. 
   Martini or Kompella Draft is a document produced by the Internet Engineering Task Force (IETF) for the purpose of discussing a possible change in standards that govern the transport of Layer 2 frames over MPLS. 
   MPLS (Multi-Protocol Label Switching) is a communications method that uses multi-protocol labeling to establish a link or to route information between two parties. The labeling process generally involves attaching information associated with the permission level of the requesting process to an incoming or outgoing data message. 
   QoS (Quality of Service) is the required or desired level of network performance, often characterized by key attributes, such as bandwidth, delay, jitter, loss and the like. 
   SDH (Synchronous Digital Hierarchy) is a high-speed network that provides a standard interface for communications carriers in Europe to connect networks based on fiber-optic cable. It is designed to handle multiple data types such as voice, video, etc. It is an International Telecommunications Union (ITU) recommendation implemented in Europe and similar to the Synchronous Optical Network (SONET) standard used in North America and Japan. 
   A Virtual Circuit is a connection between communicating computers that provides the computers with what appears to be a direct link but can actually involve routing data over a defined, but longer path. A virtual circuit is not a physical entity; it is a logical entity. Multiple virtual circuits may exist across a single physical circuit. 
   VPN (Virtual Private Network) can be described as a wide area network (WAN) formed of permanent virtual circuits on another network, especially a network using technologies such as Asynchronous Transfer Mode (ATM), Multi-Protocol Label Switching or Frame Relay. It is also described as a set of nodes on a network that communicate in such a way that messages are safe from interception by unauthorized users as if the nodes were connected by private lines. 
   X.25 is one of a set of ‘X series’ recommendations for standardizing equipment and protocols used in public-access and private computer networks, adopted by the International Telecommunication Union Telecommunication Standardization Sector (ITU-T) and International Organization for Standardization (ISO). It defines the connection between a terminal and a packet-switching network by incorporating three definitions: (1) the electrical connection between the terminal and the network; (2) the transmission or link-access protocol; and (3) the implementation of virtual circuits between network users. Taken together, these definitions specify a synchronous, full-duplex terminal-to-network connection. 
   Technologies such as X.25, Frame Relay, Asynchronous Transfer Mode (ATM), MPLS, and Internet Protocol Security (IPSec), are well known VPN technologies. 
   In addition to the above, in the Detailed Description Section that follows, the description is presented, in part, in terms of program procedures executed on a computer or network device or network of computers. For completeness, it is to be understood that the instant invention is equally applicable to any customary network of computers. Such networks of computers, for example, include a standard communications protocol, such as Transmission Control Protocol/Internet Protocol (TCP/IP), Open Systems Interconnection (OSI) protocol, User Datagram Protocol (UDP), Wireless Application Protocol (WAP), and/or Bluetooth wireless communications protocol, or any other network-type protocol, local and/or global. 
   The procedural descriptions, representations or functionalities are generally conceived to be self-consistent sequence of steps leading to a desired result. For example, each step may involve physical manipulation of physical quantities, which takes the form of magnetic signals capable of being stored, transmitted, combined, compared and otherwise manipulated. 
   Additionally, the manipulations performed herein, such as capturing, outputting, provisioning, monitoring, maintaining, are often referred to in terms that may be associated with mental operations performed by a human. Human capability is not necessary, or desirable in most cases, in the operations forming part of the present invention; the operations are machine operations. Devices useful for performing operations of the present invention include networking devices, general-purpose computers or such similar electronic devices. 
   The present invention also relates to a system for performing these operations. This system may be specially constructed for its purpose or it may comprise a general-purpose computer as selectively activated or reconfigured by a software program. 
   SUMMARY OF INVENTION 
   It is a feature and advantage of the present invention to provide a networking architecture for configuring a virtual private network and/or interface that accomplishes substantially complete VPN membership decoupling. 
   It is a feature and advantage of the present invention to provide a networking architecture for configuring a virtual private network and/or interface that may replace expensive point-to-point WAN connections and dedicated hardware components. 
   It is a feature and advantage of the present invention to provide a networking architecture for configuring a virtual private network and/or interface that may replace low security Internet virtual private network and/or private network services. 
   It is a feature and advantage of the present invention to provide a networking architecture for configuring a virtual private network and/or interface that may replace unreliable performance Internet virtual private network services. 
   It is a feature and advantage of the present invention to provide a system and/or method for configuring a virtual private network and/or interface that may resolve expensive single managed VPN services. 
   It is a feature and advantage of the present invention to provide a networking architecture for configuring a network interface, usable in a virtual private network, that facilitates decoupled mediation of network services between one or more carriers. 
   It is a feature and advantage of the present invention to provide a networking architecture for configuring a network and/or interface that facilitates quality-of-service management functions. 
   It is a feature and advantage of the present invention to provide a networking architecture for configuring a network grid and/or interface that facilitates (discrete) passive and active measurement and testing throughout the network. 
   It is a feature and advantage of the present invention to provide a networking architecture for creating and managing an end-to-end supply chain of service providers and network operators to deliver a desired virtual private network. 
   It is a feature and advantage of the present invention to provide a networking architecture for configuring a virtual private network and/or interface that manages the forwarding, routing and quality-of-service differences at network interconnections of disparate service providers. 
   It is a feature and advantage of the present invention to provide a networking architecture for configuring a virtual private network and/or interface that requires minimal levels of integration between participants in the supply chain. 
   It is a feature and advantage of the present invention to provide a networking architecture for configuring a virtual private network and/or interface that may supplement a private network by reducing the private network&#39;s load to acceptable levels. 
   It is a feature and advantage of the present invention to provide a networking architecture for configuring a virtual private network and/or interface that may handle the introduction of user requirements in the form of new software applications without disturbing the existing configuration of the network. 
   It is a feature and advantage of the present invention to provide a networking architecture for configuring a virtual private network and/or interface that allows systems integrators, service providers and other entities, to extend end-to-end, service level agreement-based (SLA-based) VPNs beyond their own infrastructure. 
   It is a feature and advantage of the present invention to provide a networking architecture for constructing a virtual private network on a per customer basis. 
   It is a feature and advantage of the present invention to provide a networking architecture for constructing a virtual private network that has a closed-loop control system for service delivery. 
   It is a feature and advantage of the present invention to provide a networking architecture for constructing a virtual private network that employs a router/gateway approach. 
   It is a feature and advantage of the present invention to provide a networking architecture for constructing a virtual private network that is easily scalable. 
   It is a feature and advantage of the present invention to provide a networking architecture for constructing a virtual private network that enables a single point of responsibility and accountability for delivery and performance of the network. 
   The present invention solves the problems in one or more of the prior art approaches and provides the above-mentioned and other features and advantages, by providing a networking architecture for constructing a virtual private network in such a way that minimizes the coordination, time and expense involved in producing and delivering managed virtual private networks and VPN services, including such networks and services involving multiple carriers. 
   A preferred embodiment of the architecture of the present invention, usable in a virtual private network, is created using packet-based data that is preferably, but not necessarily, propagated through a peering point. Alternatively and optionally, non-packet data technology, such as Layer 2 technologies (i.e. Frame Relay and ATM) or time-division multiplexing, may be used. 
   One or more peering points are connected to each other in a desired configuration, such as a string, where, for example, one end of the string (or strings) is connected to a corporation&#39;s headquarter office and the other end of the string (or strings) is connected to a location other than the headquarter office. The configuration of the string or strings, stemming from one or many end points to one or many other end points, constitutes an end-to-end supply chain. In this regard, the term supply chain generally refers to the physical instantiation or configuration of a chain of suppliers comprising one or more service providers and network peering points. 
   Each peering point may be referred to as a virtual private Network Peering Point (NPP), which comprises network hardware and/or software configured in part as a VPN service performance monitoring device. Each peering point or NPP preferably employs Multi-Protocol Label Switching (MPLS) and Ethernet technology, which allows communications with similar or dissimilar VPN transport technologies. 
   Through the networking architecture of the present invention, each NPP is connected to one or more service providers, essentially facilitating multi-lateral service provider inter-connectivity. One type of inter-connectivity service involves providing connectivity between peering points. In order to facilitate the connection between two or more peering points, transit gateways are employed. Another type of inter-connectivity service involves providing connectivity between subscriber site(s) and peering point(s). Here, distribution gateways are used. 
   An interconnect domain for providing substantially complete decoupled mediation of network services between one or more carriers connected to a communications network, is disclosed. The interconnect domain includes: one or more collocation facilities, each having a network device configured to decouple connectivity of one or more carriers to the communications network, and at least one gateway associated with the network device; a route propagation system in communication with at least two gateways in one or more collocation facilities, where the propagation system comprises routers where routing information is hosted for distribution through the communications network; a management network in communication with one or more networking elements of the network device and the route propagation system to facilitate managed operation of the network device and the route propagation system; and at least one pair of single interfaces each configured with substantially the same specification for the removal of network membership information and/or specified distribution protocols from each interface. 
   The interconnect domain further enables: a gateway to carrier interconnect that substantially allows a carrier to connect to at least one of one or more network devices and one or more pairs of network devices; a gateway to gateway interconnect that substantially allows forwarding of site traffic across one or more single logical interfaces; a gateway to gateway interconnect that substantially allows for scalability of the communications network through separated data forwarding from route distribution; a gateway to gateway interconnect that substantially allows for logical separation of one or more grouping of site routing and forwarding information between gateways; a gateway to carrier interconnect that substantially allows for decoupling of network membership schemas; a gateway to carrier interconnect that allows for substantially secure connections on the gateway to carrier interconnect substantially absent denial of service attack; a gateway to carrier interconnect that substantially allows for separation of one or more gateway interfaces from one or more carrier interfaces; a gateway to carrier interconnect that allows for substantially separated ownership of a gateway from a carrier; a gateway to carrier interconnect substantially allowing for support of advanced network services including multi-carrier network enabled multicast. 
   The route propagation system of the interconnect domain: creates substantially mirrored route propagation paths allowing for substantially no single point of failure in the hosted routing; allows for grouping of one or more sites or site groups per carrier; allows for grouping on one or more sites or site groups per network; allows traffic from a grouping of one or more sites or site groups to ingress or egress a carrier as desired; allows for one or more carriers each network routing and forwarding over a single interface to be associated with a subset of one or more sites within the communications network or with all network sites. 
   The interconnect domain further enables: an interconnect that substantially allows a carrier to restrict per VPN the number of routes learned from or advertised to one or more carriers; an interconnect that substantially a carrier to summarize per VPN routes learned from or advertised to one or more carriers; an interconnect that substantially allows a carrier to load balance traffic across one or more networking devices; a single gateway router configuration that allows any IP based VPN carrier to connect to a service grid. 
   An interconnect domain for providing performance-based network services, is also disclosed. The interconnect domain comprises: at least one pair of single interfaces, each interface substantially similarly configured, for the removal of network membership information and/or specified distribution protocols from the interface, resulting in substantially complete routing separation over the interconnect domain; one or more collocation facilities, each having a network device to standardize connectivity of one or more carriers to a communications network, and at least one gateway associated with each network device; a route propagation system in communication with at least two gateways in one or more collocation facilities, the propagation system comprising routers where routing information is hosted for distribution through the communications network; and a management network in communication with one or more networking elements of the network device and with the route propagation system to facilitate operation of the network device and the route propagation system. 
   A system for providing substantially measurable network service across an interconnect domain connecting one or more carriers to the interconnect domain, is also disclosed. The system has: one or more carrier domains connected in a way that each carrier domain is logically separated therefrom, each carrier domain comprising a carrier&#39;s network backbone, and a pair of routers in communication with the network backbone; and at least one interconnect domain comprising at least one collocation facility, which has a network device and one or more gateways associated with the network device, a route propagation system for managing and controlling route propagation functions, a management network in communication with the network device and route propagation system, and a pair of substantially similar single interfaces for separating at least one of the carrier domain from the interconnect domain, the carrier domain from another carrier domain, or the interconnect domain from another interconnect domain. The route propagation system allows for traffic to fail over one of the interconnect domain and carrier domain as directed. 
   The configuration of the networking architecture of the present invention enables service provider-dual homing, which allows subscriber traffic to egress and ingress a service provider at a pair or multiples of pairs of NPPs. In this configuration, the pairs of NPPs are referred to as North and South NPPs, respectively. Each North and South NPP has a connection, referred to as a North and South connection, respectively, carried by participants in the supply chain, such as to another pair of NPPs or a subscriber gateway. The selection of which single NPP is used at any one time to forward subscriber traffic and propagate subscriber routing, is preferably a function of the service provider&#39;s routing protocols. The service provider may then optimize these traffic paths through load balancing or selectively determining individual traffic egress points. 
   The selection of which pair(s) of NPPs is/are used at any one time to forward subscriber traffic and propagate subscriber routing is preferably directed by an interconnect manager. In this embodiment, the interconnect manager preferably operates the NPPs along with the route propagation system. 
   The configuration of each NPP also allows for MPLS Label Switched Path (LSP) protection, which preferably exists between the gateways and resides with the interconnect manager. Selection of the backup path is dynamic such that backup path selection (data convergence) is performed by the gateways, based on directed paths that exist between the NPPs. 
   With respect to routing, each NPP is configurable to support a variety of route propagation methodologies for inter-connecting service providers. For example, one route propagation method the NPP is configurable to support is a MPLS virtual router interconnection where one or more VPNs are interconnected using internet protocols (IP) over a single logical interface per VPN. In other words, the routing/data forwarding interconnect supported from a service provider domain to a peering point is an MPLS virtual router interconnection where one or more VPNs are preferably interconnected using internet protocols (IP) over logical interfaces per VPN. Another method may employ a multi-hop, multi-protocol Exterior Border Gateway Protocol (EBGP), where participant service providers use a transparent layer two (L2) VPN transport mechanism. 
   In addition, devices or routers are preferably centrally located in what may be termed a routing nexus. Multiple routers comprise the routing nexus, where subscriber routing information is hosted and selectively distributed to deliver virtual private networks. Preferably, a minimum of two routers is dedicated to each service provider for multi-protocol BGP route distribution. These routers are preferably divided between a minimum of two geographically distributed and secure operations centers. 
   Also, creating mirrored, separate route propagation paths for all subscriber routes is likely to increase route propagation availability. Principally, there is virtually no single point of failure in the supply chain. 
   In this respect, and before explaining at least one embodiment or aspect of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the figure drawings. 
   The present invention is capable of other embodiments and of being practiced and carried out in a variety of ways. For example, one embodiment falling within the scope of the claims may be described as a method of procuring VPN service. The method includes, in part, the steps of capturing subscriber requirements, formulating one or more solutions based on the subscriber&#39;s requirements, and formulating one or more price quotes based on a selected solution. 
   In another instance, the VPNs are not limited in the number of sites or the nature of inter-connectivity between sites; in other words, the present invention is not limited to point-to-point connections. It could be any combination of connectivities, such as point to multi-point or full mesh. 
   The present invention is also not limited to the number of peering points or service providers, illustrated herein, and used to comprise the supply chain. The number of peering points and/or service providers may reach into the hundreds, for example. 
   Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting the invention. Those skilled in the art will appreciate that the conception, upon which this disclosure is based, may be readily used as a basis for designing other structures or infrastructures, methods and/or systems for carrying out the several purposes of the present invention and its several aspects. Therefore, it is important that the claims be regarded as including such equivalent constructions and/or structures insofar as they do not depart from the spirit and scope of the present invention. 
   The above features and/or advantages of the invention, together with other aspects of the invention, along with the various features of novelty that characterize the invention, are pointed out with particularity in the claims appended to and forming a part of this disclosure. 

   
     BRIEF DESCRIPTION OF PREFERRED EMBODIMENTS 
       FIG. 1  is a block diagram of a configuration of a network peering point, usable in the networking architecture of the present invention. 
       FIG. 2  is a block diagram showing a configuration of the peering point of  FIG. 1  in one arrangement of a network node usable in the networking architecture of the present invention. 
       FIG. 3  is a block diagram showing a virtual private network employing the networking architecture of the present invention, in accordance with one embodiment of the present invention. 
       FIG. 4  is a block diagram showing one embodiment of multiple scaling connections capable with the networking architecture interface of the present invention. 
       FIG. 5  is a flow diagram showing one embodiment of routing nexus resiliency achieved by the present invention. 
       FIG. 6  is a flow diagram showing optimal path routing through one configuration of the networking architecture of the present invention. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   The present invention relates to the construction and configuration of a networking architecture and interface, preferably usable in virtual private networks (VPN) and VPN services in the form of a supply chain. A supply chain generally refers to the physical instantiation or configuration of a chain of suppliers comprising one or more carriers and network devices/peering points, generally interconnected together. The networking architecture and interface of the present invention allows for a variety of applications. 
   For convenience, the description of the present invention will be explained with reference to the data environment, particularly packet-based data. Alternatively and optionally, non-packet-based data approaches, such as time-division multiplexing, are also applicable. 
   In accordance with the invention, a gateway is used to connect the subscriber&#39;s network environment to the networking architecture/interface configuration of the present invention. It is very common that the subscriber&#39;s environment is an Internet Protocol (IP) gateway or router. 
   In a best mode of the invention, each NPP is connected to one or more service providers, essentially providing multi-lateral service provider inter-connectivity. One type of inter-connectivity service involves providing connectivity between peering points. In order to facilitate the connection between two or more peering points, transit gateways are employed. 
   In a preferred embodiment, each transit gateway is arranged with and preferably connected to a peering point or NPP using a high speed Ethernet connection. The transit gateway, which is a network device preferably owned and/or managed by a service provider, has a NPP side and a transport side. 
   The NPP side of the transit gateway is substantially directly connected to the NPP. Each transit or service provider gateway is capable of transporting Ethernet frames on the NPP side. The transport side of the transit gateway is capable of connection to one or more transit gateways generally located at another NPP. 
   As such, on the transport side, the transit gateway is configurable to transparently tunnel Ethernet if applicable over a variety of different VPN transport technologies, such as Ethernet, MPLS, Frame Relay, ATM, SDH, and the like. 
   Another type of inter-connectivity service involves providing connectivity between subscriber site(s) and peering point(s). Here, distribution gateways are used. 
   In a preferred embodiment, each distribution gateway is arranged with and preferably connected to a peering point using a high speed Ethernet connection. 
   Each distribution gateway is arranged with and connected to the NPP using Ethernet or Gigabit Ethernet technology. The distribution gateway, which is a network device, has a NPP side and a transport side. 
   The NPP side of the distribution gateway is substantially directly connected to the NPP. Each distribution or service provider gateway operates Internet protocols over MPLS over Ethernet on the NPP side. The transport side of the distribution gateway is capable of connection to a subscriber&#39;s gateway, which comprises a customer&#39;s network equipment generally located at the customer&#39;s site. 
   As such, on the transport side, the distribution gateway is configurable to operate Internet protocols separated by link layer protocols such as Frame Relay, ATM, PPP and the like. Each NPP is preferably connected to two or more routers via a management network, all of which manages subscriber route propagation and enterprise traffic forwarding throughout the supply chain in conjunction with implementation systems. 
   Referring now to  FIG. 1 , there is shown a preferred embodiment of a configuration of a network peering point  2  usable in the networking architecture of the present invention. Each peering point  2  may be referred to as a Network Peering Point (NPP)  2 . Each NPP is preferably arranged having a left rack and a right rack. Each NPP  2  comprises network hardware and/or software, including operating instructions. Preferably, each NPP includes right and left components for redundancy. 
   The network hardware and/or software preferably includes two Ethernet NPP switches  4 , an operating system platform  6 , such as an OSS platform, one or more routers  8 , localized storage (not shown), and a service control device  10 . The service control device(s)  10  enables the NPP  2  to operate, in part, as a VPN service performance monitoring device, and for quality-of-service management between connecting service providers. 
   Additionally, each NPP  2  preferably employs Multi-Protocol Label Switching (MPLS) and Ethernet technology, which allows the NPP  2  to communicate with similar or different VPN transport technologies on either side of the NPP  2 . Communication with different VPN technologies is achieved by a combination of a service provider gateway, for instance, and normalization to MPLS. The NPP  2  is the fundamental building block of the virtual private network. The NPP  2  is also a fundamental component of a supply chain and delivery of the virtual private network. 
   Referring now to  FIG. 2 , there is shown one configuration of the peering point of  FIG. 1  in one arrangement of a network node usable in the networking architecture of the present invention. The principal components of the network node comprises a NPP  2 , a management network  22 , and a route propagation system  21  which includes one or more routing nexus  24 ,  60 . 
   As depicted, the NPP  2  is preferably configured with two or more routers or gateways  12 ,  16  located on either side of the NPP  2 . 
   The gateways  12  may take the form of a distribution gateway or a transit gateway, depending on the nature, geographical coverage, and role of the service provider in the supply chain. A distribution service provider provides localized, national or global coverage, and connects to the NPP  2  via a distribution gateway. Further, a distribution service provider provides managed IP service connectivity between a subscriber gateway  20  and a NPP  2 . 
   On the other hand, a transit service provider provides layer 2 connectivity between NPPs  2 . There may be one or more distribution service providers connected to each NPP  2 . There may be one or more transit service providers connected to each NPP  2 . 
   The distribution gateway  12 , which is network hardware, has what may be termed as a NPP side  16  and a transport side  18 . The NPP side  16  of the gateway  12  is in substantially direct connection to the NPP  2 . Each gateway  12  is preferably capable of transporting Ethernet frames on the NPP side  16  for transporting site or enterprise traffic. 
   On the transport side  18 , the gateway  12  is capable of operating Internet Protocols (IP) separated by whatever choice of technology the service provider desires. As depicted, the choice of technologies may include, but is not limited to, Frame Relay, Asynchronous Transfer Mode (ATM), SDH and IPSec. Accordingly, the transport side  18  is very flexible; it is capable of connection to another gateway  12 , if it is a transit gateway, which indicates connectability to another peering point or NPP  2 , or it is capable of connection to a subscriber&#39;s gateway  20 , if it is a distribution gateway, which is generally located at the subscriber&#39;s premises. 
   A management network hardware and/or software  22  is in substantially direct connection with each NPP  2  to facilitate operation of the NPP  2 , such as, for example, in-band management, route propagation, performance statistics, configurations, and the like. Given the reliable and redundant nature of the supply chain network configuration, substantially all connectivity to one or more remote NPPs  2  is in-band, essentially removing the need for an extensive and expensive global management network. 
   In addition, a route propagation system  21 , in communication with one or more routing nexuses  24 ,  60 , manages and securely controls subscriber route propagation and distribution. The route propagation system  21  and routing nexus  24 ,  60  operate substantially in connection with the management network  22 . 
   A virtual private network employing the networking architecture and interface of the present invention, is shown in  FIG. 3 . 
   As depicted, two collocation facilities  40 ,  42 , each containing its own NPP  44 ,  46  respectively, are connected together via multiple service providers, SP 1 , SP 2 , SP 3  between two remote subscriber sites  48 ,  50 . A more detailed description is provided below. 
   Each subscriber site  48 ,  50  generally comprises network equipment, including the subscriber&#39;s gateway  20 , on the customer&#39;s premises. In providing VPN service from site  48  to site  50 , the VPN architecture is configured as one or more interconnect domains A, B, C, to include a plurality of service providers intermediate each subscriber site  48 ,  50  and intermediate each collocation facility  40 ,  42 . 
   More specifically, the subscriber site  48  communicates with site  50  through VPN connectivity involving interconnect domains A, B, C and interfaces  41 ,  43 ,  45 ,  47 . Interconnect domain A describes the SP 1  domain, which comprises a pair of routers  51 ,  53  on either side of SP 1 . Similarly, interconnect domain C describes the SP 3  domain, which comprises a pair of routers  55 ,  57  positioned on either side of the SP 3  backbone. The routers  51 ,  53 ,  55 ,  57  are preferably owned and/or operated by the respective service provider SP 1 , SP 3 . 
   The interconnect domain B includes an interconnect domain comprising collocation facility  40 ,  42  and a network backbone shown as SP 2 . Within each collocation facility  40 ,  42  are contained two pairs of gateways  52 ,  54 , and  56 ,  58 , respectively. Gateways  52 ,  54 ,  56 ,  58  may be owned and/or operated by a service provider or providers. In other words, although the gateways  52 ,  58  may be dedicated to service provider SP 1 , SP 3 , respectively, these two gateways  52 ,  58  need not be owned by service provider SP 1 , SP 3 . Gateways  52 ,  54  are located on either side of the NPP  44  in collocation facility  40 , and gateways  56 ,  58  are located on either side of the NPP  46  in collocation facility  42 . 
   Preferably, gateways  52  and  58 , which are in substantially direct communication with routing nexus  24 ,  60  are distribution gateways. Additionally, gateways  54  and  56 , which connect the two collocation facilities  40 ,  42 , are transit gateways, so called since they are managed and/or operated by transit service providers. 
   As depicted in  FIG. 3 , the distribution gateway  52  presents one or more transport interfaces on the transport side, toward the service provider SP 1 , and provides Virtual Local Area Network (VLAN) Ethernet interfaces on the NPP side, toward the NPP  44 . The main properties of the gateway  52  are protocol conversion, forwarding and route propagation. Preferably, the gateway  52  uses BGP and multi-protocol BGP (MBGP) route propagation. 
   The NPP  44 , like the NPP  46 , is preferably owned and/or operated by a NPP Operator, and includes Ethernet switches  4  ( FIG. 1 ) used to interconnect two or more gateways  52 ,  54 , for example. NPP switches  4  are used to establish connection-oriented paths between collocation facilities  40 ,  42 . In addition, the NPP switches are used to establish substantially connectionless paths between routing nexus facilities  24 ,  60 . Moreover, the NPP switches are also used to establish locally switched paths to local monitoring instrumentation devices. 
   The main properties of the NPP Ethernet switches  4  are forwarding, tunneling and MPLS traffic engineering. These switches provide one or more Ethernet transport interfaces to the gateways  52 ,  54  as appropriate, and maps VLANs and other virtual path mechanisms to MPLS Label Switched Paths (LSPs) where applicable. A range of Layer 3 IP VPN transport mechanisms, such as MPLS, ATM or Frame Relay, may be used by service providers SP 1 , and SP 3 , for their part of the forwarding path in the virtual private network. In addition, a range of Layer 2 VPN transport mechanisms, such as Ethernet, MPLS, Frame Relay, ATM or L2TPv3, may be used by service provider SP 2  for its part of the forwarding path in the virtual private network. These layer 2 VPN transport mechanisms appear as logical point-to-point circuits to the NPP switches  4 . 
   The transit gateway  54 , like the gateway  56 , is likely owned and/or operated by the service provider SP 2 . The main properties of the gateway  54  (and gateway  56 ) are protocol conversion and forwarding. Preferably, transit gateways  54 ,  56  do not perform route propagation. Transit gateway  54  provides one or more transport interfaces to the service provider SP 2  on the transport side, as well as VLAN Ethernet interfaces to the NPP  44  on the NPP side. 
   The above explanation is similar for the collocation facility  42 , with the exception that the gateways  54 ,  56 , likely owned and/or operated by the service provider SP 2 . 
   The routing nexus  24 ,  60  are in substantially constant communication with the distribution gateways  52 ,  58  at the collocation facility  40 ,  42 , respectively. Together, the routing nexuses  24 ,  60  acts as a dual redundant cluster of border routers where at least one router in each nexus  24 ,  60  is dedicated to and operates in conjunction with each service provider gateway and supports route propagation in accordance with conventional techniques. 
   A significance of the interconnect domains A, B, C configured in the manner depicted in  FIG. 3  is further elaborated with reference to  FIGS. 4 and 5 , etc. 
   In the networking architecture and interface illustrated in  FIG. 3 , for example, the configuration of interface  41  preferably employs layer 1 and layer 2 protocols for packet transmission between the managed router  20  at site  48  and the edge router  51 . In a preferred embodiment, the specifications of interface  41  is any Open Systems Interconnection (OSI) link layer 2 protocol operating over any OSI physical layer 1 medium, and may be running a desired routing protocol such as a border gateway protocol (BGP). In addition, the configuration of interface  41  does not permit the forwarding or receiving of MPLS-labeled packets or MPLS-related label distribution protocols, or the forwarding of MPLS VPN membership information. VPN/network membership attributes may comprise route target values, route distinguisher values, and the like. 
   In addition to the removal of MPLS VPN membership information from interface  41 , the removal of interface  41  addressing from the address space of the SP 1  backbone results in substantially complete routing separation between site  48  and the SP 1  backbone. In other words, as interface  43  shares substantially identical configuration parameters as interface  41 , interface  43  serves to logically separate the backbone of SP 1  from the gateway  52 . Accordingly, the backbone of SP 1  essentially spans interconnect domain A, or SP 1  Domain A, only. Applying the same principle to interface  45  results in the separation of the SP 3  backbone, which spans interconnect domain C, or SP 3  Domain C, only. The networking interface of the present invention also facilitates standardized interconnections of one or more dissimilar carrier technologies. 
   Notably, the gateway  52  has a similar configuration to routers  53 ,  55  in that the connections between gateway  52  and gateway  58 , for instance, across peering points  44 ,  46  in collocation facility  40 ,  42 , respectively, carry site  48  VPN traffic separated by MPLS labels. As such, the interconnect domain B exhibits similar traffic forwarding properties of SP 1  Domain A and SP 3  Domain C, with MPLS VPN membership attributes, such as Route Target and Route Distinguisher values, spanning the Interconnect Domain B only. Thus, the networking architecture and interface configuration depicted in  FIG. 3  accomplishes substantially complete VPN membership decoupling of the SP 1 , SP 2 , SP 3  backbones by allowing site traffic from one service provider backbone to pass to another service provider backbone through the intermediary Interconnect Domain B. In this regard, Interconnect Domain B serves as an Interconnect Manager, which uses similar principles as associated with a single service provider backbone in the allocation and provisioning of MPLS VPN membership information to enable the backbones of more than one VPN service provider (i.e. SP 1 , SP 3 ) to communicate with each other. 
   What is more, the inventors discovered that by configuring interfaces  43 ,  45  in a substantially identical manner as interface  41  or  47 , using one or more external BGP peering sessions, the following combination of results followed. 
   First, the peering session is useful, at a minimum, to forward and learn per-VPN route updates between the backbones of SP 1  and SP 3 . Additionally, from a service provider perspective, the peering session is also usable by SP 1 , for example, to restrict the number of routes advertised to or learned from the SP 1  backbone. The service provider SP 1  may also use the peering session to summarize route updates advertised to or learned from provider backbones other than SP 1 , such as SP 3 . 
   Second, in instances where a provider backbone is MPLS based, only a single gateway configuration support (as at  52 ) is required for VPN connectivity to the Interconnect Domain B. Gateway  52  is also configurable to support, for example, IP over ATM (Asynchronous Transfer Mode), IP over Frame Relay, IP over Ethernet, IP over SDH (Synchronous Digital Hierarchy), IP over DSL, and the like. 
   Third, in instances where a provider backbone is not MPLS based, the same single gateway configuration (as at  52 ) is the only support required for VPN connectivity to Interconnect Domain B. This is possible due to the gateway transparently supporting IP over any layer 2 based technology. 
   Fourth, VPN membership decoupling results in a simplified infrastructure support for advanced network services such as multiple service provider VPN multicasting, the process of sending a message simultaneously to more than one destination on the  FIG. 3  networking architecture/interface. This simplification results in large measure because each domain boundary (i.e. SP 1  Domain A, Interconnect Domain B and SP 3  Domain C) has separated Multicast Distribution Trees (MDT). Each MDT is independently configurable and manageable by a service provider, and may use separate multicast routing protocols. 
   Fifth, because the configuration of each interface  43 ,  45  is separated at the data link layer or physical layer (layer 2 and layer 1, respectively, in the OSI model), each interface  43 ,  45  is capable of supporting multiple IP-based traffic flows. This capability in turn allows multiple scaling of site  48  to site  50  connections across one or more service provider backbones. 
     FIG. 4  shows one embodiment of multiple scaling connections capable with the networking architecture interface of the present invention. Here, multiple sites  31 ,  33 ,  35  are hosted by SP 1  via interface  41  on the SP 1  backbone. The sites grouped as  31  are associated by SP 1  to a single interface  43   a . Similarly, the sites grouped as  33 ,  35  are associated by SP 1  to a singular interface  43   b ,  43   c , respectively. As all the sites  31 ,  33 ,  35  are members of the same virtual private network, the traffic forwarded on to other service provider backbones through the peering point  44  is forwarded from gateway  52  across a single interface connection  49 . 
   As discussed, multiple VPN connections are configurable between router  53  and gateway  52 . Moreover, each router  53  to gateway  52  interface  43   a ,  43   b ,  43   c  shares VPN membership information with multiple sites  31 ,  33 ,  35 , respectively. This association illustrates that two or more sites  31 ,  33 ,  35  may communicate with a single interface  43 . In addition, multiple router  53  to gateway  52  interface  43   a ,  43   b ,  43   c  may forward and receive traffic across a single MPLS based interface  49 . 
   As a practical matter, generally, there is no limit to the number of peering points and/or gateways and/or networking architecture and/or networking interface and/or service providers in a supply chain VPN. Nor is there any limit to the number of service providers attachable to each peering point or gateway or Interconnect Domain or Interconnect Manager. In a preferred embodiment, one or more carriers are connectable at interconnection points, preferably an interconnect domain, in a network grid. A grid generally refers to a collection of one or more carriers and interconnect points together. 
   A more detailed description is provided below with reference to  FIG. 5 , which shows one embodiment of simplified route propagation thereby enhancing routing resiliency. 
   Each subscriber site  48 ,  50  generally comprises network equipment, including the subscriber&#39;s gateway  20 , on the customer&#39;s premises. In providing VPN service from site  48  to site  50  in  FIG. 5 , for instance, the networking architecture is configured to include two service providers SP 1 , SP 3  intermediate each site  48 ,  50 . The plurality of service providers SP 1 , SP 3 , gateways  52 ,  58  and routing nexus  24 ,  60  forms the supply chain. 
   As to route propagation, the routing protocols associated with service provider SP 1  dynamically determines subscriber data packets flowing from site  48  to site  50 . Preferably, the gateway  52   a ,  52   b ,  58   a ,  58   b  uses BGP route propagation. 
   More specifically, for a site  48  to communicate with site  50  across the VPN supply chain as depicted, a single VPN route is advertised from site  48 , operated by service provider SP 1 , and forwarded to the gateways  52   a ,  52   b  through routers  53   a ,  53   b , respectively. On gateways  52   a ,  52   b , the VPN route is advertised to routing nexus (west)  24  and routing nexus (east)  60 . 
   However, the VPN route advertised by gateway  52   a  is different to the VPN route that is advertised by gateway  52   b . This routing difference is achieved by attaching different route distinguisher values at gateways  52   a ,  52   b  to the route associated with site  48 . In routing nexus  24 ,  60 , peering routers dedicated to SP 1  receive both VPN routes for site  48  from gateways  52   a ,  52   b  and forwards both routes to the peering routers dedicated to service provider SP 3 . 
   In this manner, the propagation of routing updates between the gateways  52   a ,  52   b ,  58   a ,  58   b  and the routing nexus  24 ,  60  is enhanced to include further resilience across potential single points of routing failure within the routing nexus  24 ,  60  or the routing nexus locations themselves. As described and depicted, this enhanced routing resiliency is accomplished by allowing the west and east routing nexus pair  24 ,  60  to act in parallel in the controlled forwarding of routing updates between the gateways. Parallel route propagation between service providers SP 1 , SP 3  allows for the failure of any routing nexus device or single routing nexus location without adversely affecting the forwarding of site traffic flows between the gateways to its intended destination(s). 
   To reiterate, the above-mentioned configuration evidences the plurality of network redundancy of the present invention. As part of the supply chain, there is a north path between transit gateways  52   a ,  58   a , and a south path between transit gateways  52   b ,  58   b . Generally, subscriber traffic may be load-shared across these two connections. In the event of a failure of either of these paths, substantially all subscriber traffic is switched to the other available path. 
   A noteworthy observation is the use of dynamic layer 3 routing protocols between the gateways  52 ,  58  across layer 2 technologies. Such use does not perform enterprise or site routing distribution functionalities for the supply chain, as this is handled by the routing nexus  24 ,  60 . Instead, such use is employed to detect substantially any failure in network connectivity. 
   As earlier described, the main properties of the peering point Ethernet switches  4  are forwarding, tunneling and MPLS traffic engineering. These switches provide one or more Ethernet transport interfaces to the gateways  52   a ,  52   b ,  58   a ,  58   b  as appropriate, and maps VLANs to MPLS Label Switched Paths (LSPs). A range of Layer 2 VPN transport mechanisms, such as ATM or Frame Relay, may be used by service providers SP 1 , SP 3 , for their part of the forwarding path in the virtual private network. 
   The main properties of the gateways  52   a ,  52   b  (and gateways  58   a ,  58   b ) are protocol conversion and forwarding. Distribution gateways  52   a ,  52   b  provide one or more transport interfaces to the service provider SP 1  on the transport side, as well as VLAN Ethernet interfaces to the peering points  44 A,  44 B on the NPP side. 
   As depicted by the x, y, z lines in  FIG. 6 , the routing nexus  24 ,  60  are in substantially constant communication with the distribution gateways  52   a ,  52   b ,  58   a ,  58   b  they support. For redundancy to increase availability of route propagation in the supply chain, as shown, both routing nexus  24 ,  60  are arranged to operate with the distribution gateways  52   a ,  52   b ,  58   a ,  58   b . Preferably, each routing nexus  24 ,  60  contains a redundant cluster of border routers where at least one router in each nexus  24 ,  60  is dedicated to each service provider SP 1 , SP 3  and supports route propagation in accordance with route distinguisher and route target values. 
   Route propagation between distribution gateways  52 ,  58  is enabled by the routing nexus  24 ,  60 , respectively. Route propagation may be implemented, in part, using conventional techniques facilitated by proprietary route propagation management configuration(s) (developed by the inventors), which allows a service provider to only receive the route(s) it needs. In one embodiment, each routing nexus  24 ,  60  is preferably equipped with at least one border router per service provider. 
   Various route propagation techniques for interconnecting service providers may be used in the networking architecture of the present invention. Combined with dynamic MPLS label distribution and IP address mapping configuration, the network architecture of the present invention may support, for example, three inter-service provider routing techniques. 
   For instance, as shown in  FIG. 4 , one propagation technique employs a MPLS virtual router interconnection, such as VPN Routing and Forwarding (VRF) to VRF, (as at  43   a ,  43   b ,  43   c ), where two or more virtual private networks are interconnected using BGP protocols and forwarded to the peering point  44  via a single logical interface  49 . This technique is generally suitable for all IP based VPN service providers. A major advantage is decoupled secure communication between sites within a single interconnect or service provider domain. 
   The architecture of the present invention may also support a second route propagation technique, which employs Provider Edge-Autonomous System Border Routers (PE-ASBR). These routers employ EBGP to re-distribute labeled VPN v4 routes from Autonomous System (AS) to AS. 
   For operational scaling, a Provider Edge Autonomous System Border Router (PE-ASBR) approach to route propagation is the preferred methodology. Under this approach, VPN routes are propagated through a single, multi-protocol exterior border gateway protocol device or devices (for redundancy) from which routes are passed, under desired control, only to service providers that need to receive them, based on VPN participation. Employing this technique greatly reduces the configuration and complexity of the virtual private network. 
   As to the scalability of the virtual private network of the present invention, because routing and forwarding functions are separated within each peering point  2 , the VPN of the present invention is easily scalable to support both increases in the number of VPNs and/or routes created as well as increasing subscriber bandwidth demands.  FIG. 5  shows an example of the scaling benefits inherent in interfaces  41 ,  43  across the backbone of service provider SP 1  to the peering point  44 . 
   As to security of the VPN of the present invention, preferable dedication of router(s) to each service provider serves to minimize the probability of a service provider flooding a multi-protocol EBGP session with flapping or invalid routes, for example. Because these routers only learn routes appropriate to the associated service provider, the need for per-service provider access lists, in order to filter routes not destined for the associated service provider&#39;s network, is thus substantially eliminated. Additionally, there is substantially no layer 3 addressable component intermediate within the supply chain, another attribute that provides additional isolation and, consequently, security. These advantages may be better appreciated with reference to the next embodiment discussed below. 
   In the embodiment of  FIG. 3 , for example, multiple routers form each routing nexus  24 ,  60 . These routers preferably have secure, private in-band connections to distribution gateways  52 ,  58 , for example, which perform the Provider Edge Autonomous System Border Router (PE-ASBR) function. Also, each distribution gateway  52 ,  58  preferably has dual multi-protocol EBGP sessions to geographically separate border routers, which may be located in the dual geographically distributed routing nexuses. 
   A visual presentation of how the configuration of interface  43 ,  45  in a manner substantially identical to interface  41 ,  47 , facilitates a scalable solution for constructing optimized, symmetrical traffic paths between the backbones of service providers SP 1 , SP 3 , may be instructive with reference to  FIG. 6 . 
   By way of overview,  FIG. 6  is a flow diagram showing optimal path routing through the networking architecture of the present invention. More specifically, it describes how traffic flow propagates symmetrically and optimally end-to-end, from non-U.S. sites  48   a ,  48   b  hosted by service provider SP 1  to U.S. sites  50   a ,  50   b  hosted by service provider SP 3 . An underlying principle shown here is the grouping of sites or site groups per service provider. This allows each back-to-back VPN Routing and Forwarding (VRF) over a single logical interface to be associated either with a subset of sites within the VPN, or with all the sites. 
   Referring now to  FIG. 6 , there is shown a pair of service providers SP 1 , SP 3  connected to the ‘north’ gateways  52   a ,  52   b ,  58   a ,  58   b  outside and within the United States. While reference is made to the north gateways, it is understood that the same rules apply for the south gateways also. 
   The sites  48   a ,  48   b  hosted by service provider SP 1  are grouped as the Reading site group  48   a  and the Nagasaki site group  48   b . Similarly, service provider SP 3  has sites grouped as the Boston site group  50   a  and the Houston site group  50   b.    
   The optimal routing protocols for enterprise traffic requires that: traffic from the Reading site group  48   a  to the Boston site group  50   a  traverses interface  97  only; traffic from Reading  48   a  to Houston  50   b  traverses interface  98  only; traffic from Nagasaki  48   b  to Boston  50   a  traverses interface  99  only; and traffic from Nagasaki  48   b  to Houston  50   b  traverses  99  only. 
   Interfaces  97 ,  98 ,  99  between peering points are established per VPN and are configured substantially identical to interface  49  in  FIG. 4 . These interfaces are configured to be capable of forwarding per VPN traffic from multiple site groups as part of a VPN path. 
   Reading  48   a  to Boston  50   a  communication methodology: The Reading site group  48   a  requires communication with the Boston site group  50   a  through gateway  52   a . Interface  43   a  is configured on gateway  52   a  substantially identical to interface  43  in  FIG. 4 . In addition, interface  43   a  terminates at a VRF configured on the gateway  52   a  located at the London ‘north’ peering point. Note that service provider SP 1  is responsible for allowing all sites associated with the Reading site group  48   a  to communicate, at a minimum, with any per site group VRF on the gateway  52   a  that is associated with the Reading site group  48   a  through interface  43   a . Service provider SP 1  configures its backbone routers  51   a ,  51   b  accordingly to permit this association through the allocation of SP1-owned VPN membership route target and route distinguisher attributes. 
   Similarly, for service provider SP 3 , interface  45   a  is configured between its backbone and gateway  58   a . All routes for sites associated with the Boston site group  50   a  are now learned at the Boston VFR site group on gateway  58   a . In addition, all routes for sites associated with the Reading site group  48   a  are now learned at the Reading VRF site group on gateway  52   a.    
   The Interconnect Manager (not shown), by the controlled advertisement of routing updates through west and east routing nexus  24 ,  60 , allows routes learned through interface  43   a  to be advertised through interface  45   a , and routes learned via interface  45   a  to be advertised via interface  43   a . This per VPN communication is based on the careful allocation and provisioning of VPN membership information by the Interconnect Manager. These VPN membership attributes include route target and route distinguisher values, which are configured on the gateway  52   a ,  58   a  as well as at the peering routers in routing nexus  24 ,  60 . The border gateway protocol (BGP) route distribution mechanism for these routes is changed to allow the site traffic to be forwarded through interface  97 . 
   Reading  48   a  to Houston  50   b  communication methodology: Since the Reading site group  48   a  already has an interface  43   a  configured at the gateway  52   a , no further provisioning is required at the SP 1  backbone. In order, then, for the Houston site group  50   b  to communicate with Reading  48   a , a new interface  45   b  must be configured between the backbone of SP 3  and the gateway  58   b . The Interconnect Manager allocates VPN membership attributes across the gateways  52   a ,  58   b , as well as across the routing nexus  24 ,  60  that allows route updates to flow through interface  43   a  and interface  45   b . Traffic between interface  43   a  and interface  45   b  is now directed through configurations at the routing nexus  24 ,  60  across interface  98 . 
   Nagasaki  48   b  to Boston  50   a  communication methodology: The Nagasaki site group  48   b  requires communication with the Boston site group  50   a  through the gateway  52   b . Interface  43   b  is configured on the gateway  52   b . Boston  50   a  requires communication with Nagasaki  48   b  through gateway  58   b . Note that interface  45   c  is configured on gateway  58   b . Here, the Interconnect Manager allocates VPN membership attributes across the gateways  52   b ,  58   b , as well as across the routing nexus  24 ,  60  that allows route updates to flow between interface  43   b  and interface  45   c . Traffic between interface  43   b  and interface  45   c  is now directed via configurations at the routing nexus  24 ,  60  across interface  99 . 
   Nagasaki  48   b  to Houston  50   b  communication methodology: Since the Nagasaki site group  48   b  already has an interface  43   b  configured at the gateway  52   b , no further provisioning is needed at the backbone of SP 1 . Similarly, since the Houston site group  50   b  already has an interface  45   c  configured at the gateway  58   b , no further provisioning is needed at the backbone of SP 3 . Accordingly, the Interconnect Manager allocates VPN membership attributes across the gateways  52   b ,  58   b , as well as across the routing nexus  24 ,  60  that allows route updates to flow between interfaces  43   b ,  45   c . Traffic between the interface  43   b  and interface  45   c  is now directed via configurations at the routing nexus  24 ,  60  across interface  99 . 
   Notably, from  FIG. 6 , once a site group has been configured once per gateway, no additional configurations are required between the service provider&#39;s backbone and the gateway. Additionally, for scalability purposes, multiple site group traffic flows may be forwarded across single interfaces between the gateways, as illustrated by the traffic destined for or forwarded from interfaces  45   c  and  45   b  (for Houston  50   b  and Boston  50   a , respectively) across interface  99 . 
   In this regard, an objective of the VPN supply chain to allow service provider backbones to connect to multiple interconnect domains, is accomplished. As demonstrated above, this connectivity is beneficial to the service provider because the service provider can optimize multiple VPN symmetrical traffic flows to other service provider backbones that encompass shortest data paths. For each enterprise 
   By way of protocol, generally, there are several rules associated with how a site group communicates or does not communicate with other site groups across the VPN supply chain: For instance, a site group may comprise a minimum of one site with no maximum limit; a site group may only communicate across a peering point with any other site group if it shares the same VPN path; a site group cannot communicate with any other site group across more than a single VPN path; no more than a single VPN Routing and Forwarding (VRF) per site group is configured at a single gateway; multiple site groups can forward traffic across the same logical interface; a site may only belong to a single site group at any point in time; generally, enterprise sites  48   a ,  48   b  are grouped by service provider based on topology; (alternatively, sites may be grouped per service provider based on function (i.e. finance, marketing) or any other criteria specific to the site requirement); a VPN path is preferably defined as a path across an interface through the left and right halves of a gateway. A VPN path is preferably defined as the ‘left’ and/or ‘right’ interfaces  49  between a gateway  52  located at the ‘north’ and ‘south’ NPP  44 . 
   It is important to recognize that the above description describes the characteristics of a multi-lateral interconnect model that provides end-to-end service transparency over multiple potentially multi-homed carriers or service providers. 
   With respect to the criteria that allows for decoupled secure communication between enterprise sites within a single domain, the following attributes preferably defines site-to-service provider core connectivity: that the router(s) at the enterprise site communicate through a hierarchical peering model where each router does not peer directly, but rather the site router peers with the service provider&#39;s backbone router; that all connectivity into the service provider domain from the site&#39;s router is IP based and is separated and secured through VPN Routing and Forwarding (VRF) at the service provider&#39;s backbone router. 
   In instances where a service provider collocates a router or gateway at a multi-carrier interconnect peering point, as at Interconnect Domain B, the following attributes preferably defines the gateway configuration that allows for single domain decoupling and security attributes for gateway-to-carrier core communication: that the service provider&#39;s routers must communicate across multiple carrier domains through a hierarchical peering model where multiple carrier routers do not peer directly, but rather peer through a gateway; and that all connectivity into the service provider domain from the gateway must be IP based and separated and secured through VPN Routing and Forwarding (VRF) at the carrier routers as well as at the gateway routers. 
   With respect to the criteria that allows for service provider router-to-router communication within a single MPLS VPN enabled domain, the following attributes preferably defines desirable scaling and communication attributes: that the VPN Routing and Forwarding (VRFs) on service provider routers are not directly connected across a provider&#39;s domain, but rather are logically separated via Label Switched Paths (LSPs); and that single LSPs transport multiples of VRF-based traffic across a single provider&#39;s domain. 
   With respect to the criteria that allows for gateway-to-gateway communication across more than one provider peering point, the following attributes preferably defines desirable communication and scaling single domain characteristics: that the VPN Routing and Forwarding (VRF) on gateways must not be directly connected across peering points, but rather are logically separated via LSPs. This separation allows for controlled per-VPN communication between gateways where multiple VRFs across gateways can communicate without multiples of per VPN bilateral connections. This VRF decoupling enables the optimization of site-to-site traffic flows based on shortest data paths. Second, that single Label Switched Paths (LSPs) may transport multiples of VRF-based traffic between gateways, allowing Multi-Protocol Label Switching (MPLS) to be used for the scalable multiplexing of site traffic across singular/single interfaces. 
   Notably, within a single MPLS VPN-enabled domain, site traffic is logically separated from site route distribution through a provider&#39;s use of route reflector hierarchies and backbone routers that forward traffic without learning VPN route updates. This separation of control traffic (via MP-BGP route updates) from forwarding traffic (via MPLS-labeled packet forwarding across backbone routers) allows for a highly scalable architecture capable of supporting large numbers of end-user sites. 
   As such, the gateway must have single MP-BGP peering sessions into a centralized controlled route distribution hierarchy, with each peer capable of transporting multiples of per-VPN routes. This requirement allows for the scaling of VPN route updates between gateways, as well as avoiding a MP-BGP full mesh. In addition, the peering points need not learn VPN route information in order to forward site traffic. 
   What is more, the network and interface configuration of the present invention addresses and/or solves the following interconnect challenges: 
   Security: Since all connections from the gateway to a provider&#39;s router are terminated within VRFs, IP addressing at the gateway and subsequently across the peering points may comprise private address space and be logically separated from the provider&#39;s address space. The result is elimination of the possibility of Internet-based attacks across the peering points. 
   Gateway ownership: The gateway is not a part of the provider&#39;s core since it connects to the provider&#39;s router in substantially the same way it connects to a customer&#39;s router. Consequently, the gateway may be located externally from the provider&#39;s core at the peering point. Additionally, the gateway may be owned and/or operated by a third party. 
   Service continuity: Since explicitly labeled MPLS packets can not traverse gateway-to-router connections (as traffic from the gateway to the provider&#39;s core is terminated within VRFs at the provider&#39;s router), VRFs cannot forward explicitly labeled MPLS packets. This ensures that the provider&#39;s core is not exposed to MPLS-based Denial of Service (DoS) attacks. 
   Routing: As disclosed, a service provider may summarize or restrict route learning at its router(s) in substantially the same manner that the provider may restrict or summarize routing per site VPN connection. 
   VPN Membership Attributes: Route target and route distinguisher values are not forwarded across gateway-to-router connections. This feature addresses issues associated with VPN topology constructs, route target sharing and route distinguisher overlap, thereby allowing each provider to independently allocate MPLS VPN membership attributes as desired. 
   Load Balancing: Route target and route distinguisher values are appended to VPN routes per provider at the router connected to the gateway. This allows for providers using route reflectors to load balance traffic across multiples of peering points as well as provide optimized site-to-site traffic paths. 
   Scalability: The VRF at the gateway may be logically associated to multiples of end-user sites per VPN. Since this association is per provider and is implementable by the provider at the router using existing Operation Support System (OSS), a scalable default-enabled configuration for site-to-site connectivity across multiple providers may be implemented. In addition, this configuration supports meshed peer-to-peer applications such as voice or video over IP. 
   Multicast: Since provider domains are separated at the router VRF, support for VPN-enabled multicast across provider domains is simplified because carrier Multicast Distribution Tree (MDT) is separate from the gateway MDT. 
   The many features and advantages of the present invention are apparent from the detailed specification. The above description is intended by the appended claims to cover all such features and advantages of the invention, and all suitable modifications and equivalents fall within the spirit and scope of the invention. For completeness, the above description and drawings are only illustrative of preferred embodiments and is not intended to limit the invention to the exact construction and operation herein illustrated and described.