Patent Publication Number: US-11658876-B2

Title: Software defined access fabric without subnet restriction to a virtual network

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. Non-Provisional patent application Ser. No. 16/368,624, filed Mar. 28, 2019, which claims the benefit of U.S. Provisional Patent Application No. 62/791,212, filed Jan. 11, 2019, the contents of each are incorporated herein by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     The subject matter of this disclosure relates in general to the field of computer networking, and more particularly, to systems and methods for software defined access fabric without subnet restriction within a virtual network. 
     BACKGROUND 
     An enterprise network can be seen as a communication backbone for the enterprise by connecting computers and other related computing devices across different locations. Furthermore, the enterprise network also provides the enterprise features for obtaining insight regarding the functioning of each computing device connected to the network as well as accessibility to the data associated with each of the computing devices as well. 
     Depending on the size of the enterprise network, the network itself can be broken up into smaller and more efficient subnetworks. Subnets can allow connected computing devices to communicate with each other within the subnet while utilizing routers to communicate between subnets. Sizes for the subnets can depend on various factors, for example, connectivity requirements and the network technology used with the enterprise network. One example advantage for having multiple subnets within a larger enterprise network is to improve address allocation efficiency and network address utilization. Furthermore the use of subnets can improve network performance and speed, reduce network congestion, ease administration, and control network growth. Other advantages of using subnets include setting up logical divisions that help maintain separation within the network and improved network security. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       To provide a more complete understanding of the present disclosure and features and advantages thereof, reference is made to the following description, taken in conjunction with the accompanying drawings, in which: 
         FIG.  1    illustrates an example enterprise network; 
         FIG.  2    illustrates an example enterprise network in accordance with an embodiment applying the principles of this disclosure; 
         FIG.  3 A - FIG.  3 C  illustrate exemplary flow diagrams for a network management system in accordance with an embodiment; 
         FIG.  4    illustrates an example method according to an aspect of this closure; 
         FIG.  5 A  and  FIG.  5 B  illustrate examples of systems in accordance with some embodiments. 
     
    
    
     OVERVIEW 
     Disclosed herein are computer-implemented methods, computer-readable media, and systems for providing software defined access fabric without subnet restrictions to a virtual network. The methods, computer-readable media, and systems relate to receiving notifications from a switch that a host joined an enterprise network. The hosts are then assigned an address within a common subnet associated with the enterprise network. A policy is generated for the host based on the assigned address that includes assigning the host a role associated with the enterprise network (e.g. provider, subscriber). When a data packet transmission request is received at a later time, which includes identification of another host within the common subnet as a destination for the data packet, the generated policies are used to evaluate the request. Instructions are then provided to the switch based on the outcome of the evaluations. For example, if the data packet transmission request corresponds to allowed communication between the two different hosts within the same subnet outlined in the generated policies, instructions to the switch would allow the switch to carry out the data packet transmission. However, if the data packet transmission request corresponds to communications between two different hosts within the common subnet that are not permitted, instructions to the switch would instruct the switch to drop the data packet so that the transmission is not completed. 
     Description of Example Embodiments 
     The detailed description set forth below is intended as a description of various configurations of embodiments and is not intended to represent the only configurations in which the subject matter of this disclosure can be practiced. The appended drawings are incorporated herein and constitute a part of the detailed description. The detailed description includes specific details for the purpose of providing a more thorough understanding of the subject matter of this disclosure. However, it will be clear and apparent that the subject matter of this disclosure is not limited to the specific details set forth herein and may be practiced without these details. In some instances, structures and components are shown in block diagram form in order to avoid obscuring the concepts of the subject matter of this disclosure. 
     Enterprises customers may desire a subnet to go to multiple devices with Layer-3 underlay. However, many network implementations restrict a single virtual network (VN) to be associated with one subnet. For example, an enterprise customer with 1500 sites (e.g., one site for each store associated with a retail enterprise customer) may wish to utilize the power of software defined access (SD Access) to manage, group, or separate the sites. SD Access is an intent-based networking solution for an enterprise network environment. The intent-based network treats the computing network as a single system that provides the translation and validation of the business intent (or goals) into the computing network and returns actionable insights. SD Access provides automated end-to-end services (such as segmentation, quality of service, analytics, and so on) for users, computing devices, and application traffic within the computing network. One feature of SD Access is that SD Access automates network user policies so organizations (e.g. enterprises) can ensure the appropriate access control and application experience are set for any user or device to any application across the network. This is accomplished using a single network fabric across a local area network (LAN) and wireless local area network (WLAN) which creates a consistent user experience, anywhere, without compromising on security. 
     As described herein, each of the sites may have multiple virtual networks (VNs). The enterprise customer may wish to keep the same subnet across all of the sites (which would include each of their respective virtual networks). The enterprise customer may also wish to have common shared resources or services (e.g., Dynamic Host Configuration Protocol (DHCP), Domain Name System (DNS), etc.) for all the sites. However, most current network implementations are unable to keep the same subnet across multiple sites and/or virtual networks thereby providing an embodiment where each subnet would have its own virtual network. The network hardware may also be unable to support the large number of virtual networks that comes with each site having multiple subnets. 
     Aspects of the subject technology addresses these restrictions and technical obstacles by describing a mechanism where a computing network (e.g., an enterprise fabric) can be provisioned with a common subnet across a number of subscribers while having dynamic network policies that isolate those subscribers from one another. The dynamic generation of the network policies is performed when a host (e.g. client) is detected (via a switch) as the host connects/joins the computing network. This ability to configure a common subnet for all the hosts (e.g. clients) of the Enterprise accessing external shared services while keeping the separation and segmentation of multiple subscribers and their respective virtual networks within a single subnet makes the Enterprise fabric more simple and convenient to deploy with shared service without any security compromise. 
     Example Embodiments 
       FIG.  1    illustrates an example enterprise network  100 . The enterprise network  100  may have an enterprise fabric that would be used by the enterprise to manage its different sites  120 . For example, the enterprise may be a retail customer that wants to be able to manage each of its individually franchised stores (each associated with a different site). Each site  120  may have computing devices (e.g. cashier system) that the enterprise would like to manage using the enterprise fabric  110 . 
     The management of the different sites  120 , using the enterprise fabric  110 , is performed at a single headquarter site  130 . Furthermore, by using the headquarter site  130 , the enterprise is also capable of sharing resources and services (for example, via a server at the headquarter site  130 ) to each of the different sites  120 .  FIG.  1    provides an example enterprise with 1500 different sites. It should be noted that more or less sites can be present. 
     It may be desired by the enterprise that each of the sites be assigned to the same subnet  140  (e.g. common subnet). By having each of the sites assigned to the same subnet (as opposed to separate subnets), this simplifies the deployment and management for the different sites associated with the enterprise. As new sites are added and/or removed from the enterprise, these sites can be associated with the same subnet. There would be no need to track the different sites and their corresponding subnet addresses if the sites all are assigned to the same subnet. 
     Although having each of the different sites be managed by the same subnet would be a desired method of management, as illustrated in  FIG.  1   , currently there are a number of issues that prevents the embodiment from being effective. Although the exemplary arrangement, illustrated in  FIG.  1   , allows the enterprise to communicate between the headquarter site  130  with each of the different sites  120  associated with the enterprise fabric  110  assigned at the same subnet, the same can be said about communications between each of the sites  120  within the same subnet. Such communication between sites  120  within the same subnet of the enterprise fabric  110  can be performed, for example, via leaks or broadcasts/multi-cast packet transmission. 
     Each of the sites can be viewed as an independent entity (e.g. a store owned by a different franchise owner). As such, there may be no need or desire to each the sites be capable of communicating amongst each other. Furthermore, for the purposes of security, it would be desired that the sites  120  themselves be completely isolated from one another (e.g. incapable of communication between each other). Isolation of each of the sites could be possible, for example, if each of the sites  120  is assigned a different subnet whereby each of these subnets are assigned exclusively to a different virtual network. However, having each site be assigned to a different subnet would also further complicate the process of deploying the different sites and associated subnets as well as the management of the different sites and subnets in connection with the headquarter site  130 . 
     Another possible process for maintaining isolation between the different sites  120  within the same subnet  140  could be to use an access LISP (e.g. locator/identifier separation protocol). LISP is a network architecture and protocol that implements the use of two namespaces instead of a single IP address. The namespaces, known as endpoint identifiers (or EID), are associated with each of the end-hosts. The access LISP can then define which hosts (identified via their respective Internet Protocol (IP) addresses) can transmit and receive communications between themselves. The issue, however, is that hosts (and IP addresses) are generally not static. In order for the access LISP to work, each and every IP address for the different sites  120  associated with the common subnet of the enterprise fabric  110  would need to be known. Furthermore, the IP addresses for the different sites  120  cannot change. If, for some reason, some computing devices are moved from one site to a different site, the access LISP would be incapable of identifying if the IP addresses have been re-assigned properly and could potentially fail in managing the communication as originally intended. 
     Therefore, there is a need for a method that allows the sites to be associated with the same subnet but still have their respective isolation while using their respective virtual networks. The following figures describe in further detail how isolation is provided using some example embodiments. 
       FIG.  2    illustrates an example enterprise network  200  in accordance with an embodiment applying the principles of this disclosure. The example enterprise network  200  is similar to the enterprise network illustrated in  FIG.  1    except for a couple of features. A first difference pertains to the implementation of various virtual networks (VNs) at each of the different sites  220  and the headquarter site  230 . The use of virtual networks would allow the enterprise network  200  to maintain isolation between sites. Subnets provide some isolation via logical division or separation of IP addresses. However, subnet addresses of one host can be routable to other hosts so complete isolation cannot be guaranteed. 
     Furthermore, the example enterprise network  200  also includes a new feature, a map server  250 . The map server  250  (described in further details below) will be used to dynamically generate and enforce network policies. The network policies will be used to define the allowable communication between each of the sites  220  and the headquarter site  230 . The network policies are dynamically generated each time a host joins and is detected within the network (e.g. enterprise fabric  210 ). The dynamic generation of network policies provides greater flexibility as this allows for constantly changing environment (as hosts can join, leave, and re-join at any time). In the scenario that a computing device is taken offline, the previously assigned IP address for that computing device in connection with the enterprise fabric  210  is released and may be picked up by a different host connecting to the network at a subsequent time. If and when the computing device reconnects to the enterprise fabric  210 , if the computing device is assigned a new IP address, a new policy would also be created based on the new assignment. 
     The network (which will also be referred within disclosure as the enterprise fabric  210 ) provides the capability for an enterprise to connect each of its computing devices so that it can communicate and be managed. As further described in  FIG.  3 A - FIG.  3 C , the network includes various switches that facilitates different hosts in joining and communicating via the network. 
     Generally, the network (e.g. enterprise fabric  210 ) can comprise a variety of different planes (not illustrated). For example, the network can comprise an orchestration plane, a management plane, a control plane, and a data plane. 
     The orchestration plane can assist in the automatic on-boarding of edge network devices (such as switches and routers) in an overlay network. The orchestration plane can include one or more physical or virtual network orchestrator appliances that perform the initial authentication of the edge network devices as well as provide connectivity between devices of the control plane and the data plane. In some embodiments, the network orchestrator appliances also enable communication of edge network devices located behind Network Address Translation (NAT). Exemplary network orchestrator appliances that may be used with the present disclosure may include, for example, physical or virtual Cisco® SD-WAN vBond appliances and Cisco® DNA Center. 
     The management plane can be responsible for central configuration and monitoring of the network. The management plane can include one or more physical or virtual network management appliances that provide centralized management of the network via a graphical user interface (GUI). The GUI allows a user to monitor, configure, and maintain the edge network devices and links (e.g. Internet transport network, multi-protocol label switching (MPLS) network, 4G/LTE network) in an underlay and overlay network. The network management appliances can also support multi-tenancy and enable centralized management of logically isolated networks associated with different entities (e.g. enterprises, divisions within enterprises, groups within divisions, etc.). Alternatively or in addition, the network management appliance(s) can be a dedicated network management system for a single entity. In some embodiments, physical or virtual Cisco® SD-WAN vManage appliances and Cisco® DNA Center can operate as the network management appliance(s). 
     The control plane can build and maintain a network topology and make decisions on where traffic flows within the network. The control plane can include one or more physical or virtual network controller appliances. The network controller appliances can establish secure connections to each network device and distribute route and policy information via a control plane protocol (e.g., Overlay Management Protocol (OMP), Open Shortest Path First (OSPF), Intermediate System to Intermediate System (IS-IS), Border Gateway Protocol (BGP), Protocol-Independent Multicast (PIM), Internet Group Management Protocol (IGMP), Internet Control Message Protocol (ICMP), Address Resolution Protocol (ARP), Bidirectional Forwarding Detection (BFD), Link Aggregation Control Protocol (LACP), etc.). In some embodiments, the network controller appliances can operate as route reflectors. The network controller appliances can also orchestrate secure connectivity in the data plane between and among the edge network devices. For example, in some embodiments, the network controller appliances can distribute crypto key information among the network devices  142 . This can allow the network to support a secure network protocol or application (e.g., Internet Protocol Security (IPSec), Transport Layer Security (TLS), Secure Shell (SSH), etc.) without Internet Key Exchange (IKE) and enable scalability of the network. In some embodiments, physical or virtual Cisco® SD-WAN vSmart controllers can operate as the network controller appliances. 
     The data plane can be responsible for forwarding packets based on decisions from the control plane. The data plane can include the edge network devices, which can be physical or virtual network devices. The edge network devices can operate at the edges various network environments of an enterprise, such as in one or more data centers or colocation centers, campus networks, branch office networks, home office networks, and so forth, or in the cloud (e.g., Infrastructure as a Service (IaaS), Platform as a Service (PaaS), SaaS, and other cloud service provider networks). The edge network devices can provide secure data plane connectivity among sites over one or more WAN transports, such as via one or more Internet transport networks (e.g., Digital Subscriber Line (DSL), cable, etc.), MPLS networks (or other private packet-switched network (e.g., Metro Ethernet, Frame Relay, Asynchronous Transfer Mode (ATM), etc.), mobile networks (e.g., 3G, 4G/LTE, 5G, etc.), or other WAN technology (e.g., Synchronous Optical Networking (SONET), Synchronous Digital Hierarchy (SDH), Dense Wavelength Division Multiplexing (DWDM), or other fiber-optic technology; leased lines (e.g., T1/E1, T3/E3, etc.); Public Switched Telephone Network (PSTN), Integrated Services Digital Network (ISDN), or other private circuit-switched network; small aperture terminal (VSAT) or other satellite network; etc.). The edge network devices can be responsible for traffic forwarding, security, encryption, quality of service (QoS), and routing (e.g., BGP, OSPF, etc.), among other tasks. In some embodiments, physical or virtual Cisco® SD-WAN vEdge routers can operate as the edge network devices. 
     The map server  250  will be used to dynamically define the relationship between the headquarter site  230  and each of the sites  220  within the enterprise network  200 . Specifically, the headquarter site  230  will be identified, via the policies, as a provider. Each of the sites  220  will be identified as individual subscribers. 
     The map server  250  is able to implement the isolation between the different sites  220  by generating site-specific policies that only allow communications to be transmitted between a particular site within the subnet with the headquarter site, namely only communications between sites having different roles (e.g. between the provider virtual network and a subscriber virtual network) are allowed. Each of these policies are generated as different entities join and are detected within the same subnet  140 . By using the dynamically generated policies, the map server  250  can be used to detect and deny requests corresponding to communications between subscriber sites using the same subnet. 
     As illustrated in the figure, the map server  250  can be its own separate entity with respect the enterprise fabric  210 . However, there may be other embodiments whereby the map server  250  can be part of the headquarters site  230  or part of the enterprise fabric  210  itself (e.g. switches/nodes). 
     An example network policy command line interface (CLI) is provided below. The network policy command is able to be provided dynamic capabilities with the use of an ‘ip-any’ keyword which allows the map server  250  to generate policies for any IP address that is detected within the subnet  140 . 
     
       
         
           
               
             
               
                   
               
             
            
               
                 router lisp 
               
               
                 site ‘site1’ 
               
               
                 authentication-key uci 
               
               
                 eid-record instance-id 1 &lt;subnet_provider_prefix&gt; accept-more-specifics 
               
               
                 eid-record instance-id 2 0.0.0.0 accept-more-specifics 
               
               
                 eid-record instance-id 2 &lt;subnet_subscriber_prefix&gt; 
               
               
                 accept-more-specifics 
               
               
                 eid-record instance-id 3 &lt;subnet_subscriber_prefix&gt; 
               
               
                 accept-more-specifics 
               
               
                 ! 
               
               
                 extranet ext1 
               
               
                 eid-record-provider instance-id 1 
               
               
                 &lt;prefix&gt; 
               
               
                 &lt;ip-any&gt; 
               
               
                 ! 
               
               
                 eid-record-subscriber instance-id 2 
               
               
                 &lt;ip-any&gt; 
               
               
                 ! 
               
               
                 eid-ecord-subscriber instance-id 3 
               
               
                 &lt;ip-any&gt; 
               
               
                 ! 
               
               
                 ! 
               
               
                 ! 
               
               
                   
               
            
           
         
       
     
     For the above exemplary policy, the following notes are provided:
         ‘router lisp’ and ‘site’ CLI are used to configure the allowed subnet for each virtual network/Instance ID (IID). The common subnet would be configured as part of the site command for all subscriber virtual networks.   ‘router lisp’ and ‘extranet’ CLI configures the enterprise network provider and subscribers for corresponding virtual networks/instance IDs.   ‘ip-any’ would be configured as part of the network subscriber configuration for all subscriber virtual networks. For dynamic learning of the hosts and their virtual networks in the network policy, ‘ip-any’ would allow all valid registrations to be added as allowed hosts and virtual networks in the network policies.   ‘ip-any’ also allows both ipv4 as well ipv6 prefixes to be learned for the provider/subscriber as per allowed site configuration.   Both &lt;ip-any&gt; and &lt;prefix&gt; options can coexist (i.e. both of these option—dynamic learning or static policy prefixes—can be configured for the same provider/subscriber at the same time). The advantage is that a static prefix can be used for less specific EIDs (eg. /24). More specific EIDs (e.g. /32) won&#39;t be learned and dynamically added in the network policy since overlapping prefixes are not allowed. This would help the network policies to scale for dynamic EIDs if needed.   If 0.0.0.0 is used as an allowed site prefix for subscriber virtual networks/instance IDs under site configuration, another non-zero site prefix needs to be configured which would tell the common subnet used for that virtual network. For security, configuration should specify which common subnet joining hosts are part of. If all VN/IID&#39;s have 0.0.0.0 configured as allowed prefix, that means all host are allowed for all VNs which is unintended. Intention for 0.0.0.0 site configuration is to allow learning prefixes from a different secured networks (eg data center), not to allow every ip host address. Hence it&#39;s advisable to configure each VN&#39;s site prefix 0.0.0.0 (to allow learning datacenter prefixes) with a common subnet prefix to restrict host to a secured configured common subnet for dynamic inter VN communication policy.       

       FIG.  3 A - FIG.  3 C  illustrate exemplary flow diagrams for a network management system in accordance with an embodiment. Specifically,  FIG.  3 A  illustrates exemplary flows showing the detection of each host and subsequently dynamically generating network policies for the enterprise network;  FIG.  3 B  illustrates exemplary flows showing allowable communication between a subscriber and the provider; and  FIG.  3 C  illustrates exemplary flows showing what occurs when a non-permitted communication is detected between two subscribers. 
     With reference to  FIG.  3 A - FIG.  3 C , the exemplary flow diagram includes a number of different entities that are used in connection with the network management system. These entities communicate with each other via messages as the different hosts are detected, the policies are dynamically generated for the detected hosts, determining whether a communication is appropriate, and transmission of the data packets if such communication is allowed. The exemplary entities include the map server  300 , each of the hosts  310 ,  340 ,  360 , and their associated switches  320 ,  330 , and  350 . 
     The map server  300  is responsible for dynamically generating and storing the network policies. The policies, as described above, are used in the present disclosure to maintain isolation between the different subscribers within the subnet. These policies are generated when hosts join and are detected in the network. 
     Each of the hosts  310 ,  340 , and  360  correspond to different sites that are associated with the network. Each host  310 ,  340 ,  360  is identified by their respective endpoint identifiers (EIDs), which in this case would be an IP address. The hosts  310 ,  340 ,  360  join the network, are detected, and registered with the network via their respective switches  320 ,  330 ,  360 . 
     With message [1], the map server  300  can be configured to define the relationship of which hosts are able to communicate with one another within the enterprise fabric. It is here that the map server  300  is configured to define the headquarter site (illustrated as H1 in  FIG.  3 A ) as the provider and that the headquarter site would be allowed to communicate with any of the other hosts (defined as different subscribers). The map server  300  is also configured, at this point, to register any subsequent hosts (and their respective IP addresses) that join the enterprise fabric and are detected by the switches as being subscribers. These subscribers would not be allowed to communicate between each other using the generated network policies. 
     The identification of which host should be identified as the provider and which hosts are identified as subscribers can be carried out, for example, by having the map server be configured to identify which virtual networks are associated with the provider and which virtual networks are associated with subscribers. Hosts that need shared services would be instructed to connect to the enterprise fabric using virtual networks specific to subscribers. In contrast, hosts that are associated with the shared services server (e.g. headquarter site) will be instructed to connect using virtual networks specific to the provider. 
     As hosts join and leave the enterprise fabric, the map server  300  will automatically detect the IP addresses of these hosts and dynamically generate corresponding policies that allows the new subscribers to communicate with the headquarter site (e.g. provider). If for some reason a host leaves the enterprise fabric the previously assigned IP address can be released back and associated policies are deleted (so the old IP address can be reused for the next host joining the enterprise fabric). When that host rejoins, it may be re-assigned a new IP address and correspondingly be associated with new policies that are generated. In this way, the dynamic policies are available to prevent any subscribers (e.g. new or existing) from communicating with other subscribers that are currently associated with the same subnet of the enterprise fabric. The map server  300  and its associated policies can institute and maintain the desired isolation between the different hosts/sites that have virtual networks associated with the same subnet. 
     With messages [2], [4], and [6], the host (e.g. site) sends a message to their respective switch  320 ,  330 ,  350 . These messages [2], [4], and [6] are detected by the switches  320 ,  330 ,  350  as the hosts joining the enterprise network. The switches  320 ,  330 ,  350  can communicate with the map server  300  via messages [3], [5], and [7] in order to register the detected host with the map server  300 . Based on the initial definition of the relationships provided in message [1], the hosts will have their identification (e.g. IP addresses) added to the policies stored therein. 
     For example, when host2  340  joins the enterprise fabric and is detected via message [4] by the corresponding switch (xTR2)  330 , the switch (xTR2)  330  can then register the host2  340  at the map server  300 . In some embodiments, the map server  300  may require validation of authentication keys to determine whether the host2  340  is allowed within the subnet based on possible definitions provided in message [1]. When the map server  300  allows host2  340  to be registered, based on the definition provided in message [1], host2 may be defined as a subscriber within the enterprise fabric. The map server  300  will generate a corresponding policy that would allow host 2 to communicate with only the host identified as the provider (which would be host1  310 ) as illustrated in  FIG.  3 A ). A policy is generated by the map server  300  whenever a new host joins the enterprise fabric. Even when a host leaves and re-joins the enterprise fabric, if the host is assigned a different identifier (e.g. IP address), the policies within the map server  300  would account for that by generating a new policy for that host. 
       FIG.  3 B  illustrates the messages that are sent when two hosts (specifically host that has been defined as a provider and a different host that is defined as a subscriber) attempt to communicate with each other within the enterprise fabric. In particular, message [8]-message [12] illustrates the steps to determine whether a communication from Host 1  310  can be provided to Host 2  340 . Meanwhile, messages [13]-[17] provide the reverse scenario illustrating the steps to determine whether a communication from Host 2  310  can be provided to Host 1  310 . 
     In the figure, Host 1  310  and Host 2  340  wish to communicate with each other via the enterprise fabric. Message [8] illustrates that a data packet is being provided from Host 1  310  (which is defined as a provider) to its respective switch (xTR1)  320 . The packet indicates that the source is coming from Host 1  310  and would like to be provided to Host 2  340  as the destination. Upon receiving the data packet from Host 1  310 , the switch (xTR1)  320  sends message [9] to the map server  300 . 
     Message [9] is provided to the map server  300  to identify whether the communication between Host 1  310  and Host 2  340  is appropriate based on the network policies at the map server  300 . If there is a generated policy within the map server  300  that approves that the communication between Host 1  310  and Host 2  340  is appropriate, the map server  300  provides IP address of Host 2  340  back to the switch (xTR1)  320  via message [10] so that the switch (xTR1)  320  knows where to transmit the data packet. 
     Once confirmation that communication can be performed between Host 1  310  and Host 2  340 , the data packet is encapsulated so that it can be provided to Host 2  340  via message [11]. The data packet is encapsulated, for example, to provide encryption so that the data packet can be transmitted safely and securely across the enterprise fabric. The encapsulated data packet is delivered from the switch (xTR1) associated with Host 1  310  to the switch (xTR2)  330  associated with Host 2  340 . Once received at the switch (xTR2)  330 , the data packet is de-capsulated and provided to the destination Host 2  340  as originally intended via message [12]. 
     In connection with the latter half of  FIG.  3 B , the reverse scenario whereby Host 2  340  would attempt to communicate with Host 1  310  is described. Message [13] illustrates that a data packet is being provided by Host 2  340  to its respective switch (xTR2)  330 . The data packet provides information pertaining to the source being associated with Host 2  340  and the desired destination of Host 1  310 . The switch (xTR2)  330  then provides message [14] to the map server  300  to determine whether the data packet can be transmitted to Host 1  310 . 
     The map server  300  would evaluate each of the policies stored therein to ensure that Host 2  340  is not attempting to communicate with a different host that is also defined as a subscriber. Because the map server  300  would be able to identify that Host 1  310  is actually the provider associated with the enterprise network based on the stored policies, the map server  300  can provide confirmation back (via message [15]) that the data packet can be transmitted from Host 2  340  to Host 1  310 . Once the confirmation has been received via message [15], the data packet can be similarly encapsulated for security purposes and sent to the switch (xTR1) associated with Host 1  310  via message [16]. The data packet is then de-capsulated and provided to Host 1  310  via message [17]. 
     For reference, the dotted line  370  illustrates that communication between Host 1  310  (which is defined as a provider) would be allowed with Host 2  340  (which is defined as a subscriber) based on the policies generated and stored within the map server  300 . At least within this embodiment, the generated policies stored within the map server  300  are used to ensure that a provider and a subscriber are the two entities seeking to communicate with each other via the enterprise fabric. 
     In connection with  FIG.  3 C , example scenarios are described where two hosts (defined as subscribers within the same subnet) attempt to communicate with each other. Here, the map server  300  utilizes the policies to prevent such communication so that isolation can be enforced between the two hosts. In particular, messages [18]-[20] are directed to attempts by Host 2  340  to communicate with Host 3  360  while messages [21]-[23] are directed to attempts by Host 3  360  to communicate with Host 2  340 . 
     With message [18], a data packet is being provided from Host 2  340  to switch (xTR2)  330 . The data packet includes information such as the source (being Host 2  340 ) and the destination being Host 3  360 . The switch (xTR2)  330  will communicate with the map server  300  (via message [19]). Here the map server  300  will review the policies to determine if communication between Host 2  340  and Host 3  360  is allowed. Whereas, in  FIG.  3 B , communication was being performed between a provider and a subscriber within the enterprise fabric, here the map server  300  concludes that Host 2  340  is attempting to communicate with another subscriber Host 3  360 . This conclusion is reached by identifying that both Host 2  340  and Host 3  360  have been defined as subscribers within the same subnet and based on the initial definition (provided in message [1] of  FIG.  3 A ), such a communication would not be allowed within the present enterprise fabric. Therefore the map server  300  provides a negative reply back via message [20]. This negative reply instructs the data packet to be dropped by the switch (xTR2)  330  so that it cannot be sent to Host 3  360 . 
     In the scenario where a data packet is being provided from Host 3  360  to its switch (xTR3)  350  via message [21] providing information that the data packet is intended for Host 2  340 , the switch (xTR3)  350  would communicate with the map server  300  to determine whether such communication would be appropriate (via message [22]). Similar to the scenario described above, the map server  300  will notice, based on the stored network policies, that Host 3  360  is attempting to communicate with another subscriber within the same subnet. Therefore, the map server  300  will again provide a negative reply back via message [23]. This negative reply instructs the data packet to be dropped by the switch (xTR3)  350  so that it cannot be sent to Host 2  340 . 
     For reference, the dotted line  380  illustrates that communication between Host 2  310  (which is defined as a subscriber) is not allowed with other subscribers (e.g. Host 3  360 ) based on the policies generated and stored within the map server  300 . At least within this embodiment, the generated policies stored within the map server  300  are used to institute and maintain the isolation between different sites/hosts. By forcing the data packets to be dropped in this manner, the map server  300  can maintain isolation between subscribers within the same subnet while still allowing each subscriber to communicate with the provider as needed. 
       FIG.  4    illustrates an example method  400  according to an aspect of this disclosure. The method  400  describes the various steps for establishing an enterprise fabric that allows for multiple sites (defined as subscribers) to co-exist within the same subnet while still maintaining isolation between the different sites. Furthermore, each of the subscribers would still be allowed to communicate with the headquarter site (defined as the provider) within the enterprise fabric with the headquarter site also being capable of sharing resources and services with each of the subscribers. 
     In step  410 , the map server is configured to allow only communication between a provider and a subscriber within the enterprise fabric. Furthermore, the map server can also be configured to allow certain hosts to connect to the enterprise fabric and may also determine what hosts can be defined as being the provider. Here, the use of ‘ip-any’ prefixes within the map server provides for a dynamic learning environment where valid hosts (defined as subscribers) would be provided a specific policy that would allow those hosts to communicate with the provider and to have resources and services from the provider shared. 
     In step  420 , the enterprise fabric detects the hosts as they join the enterprise network. The hosts are detected when they communicate with switches that provide the hosts access to the enterprise network. 
     The switches then forward the host information to the map server in step  430 . While at the map server, validation can be performed to determine if the host is allowed to access the enterprise network. If authorized, the host can be assigned an IP address within a subnet. Based on the initial configuration of the map server in step  410 , the host can be defined as either the provider or a subscriber. If identified as a subscriber for the enterprise fabric, policies will be dynamically generated describing that the host would only be allowed to communicate with the host defined as the provider. Any other communications (e.g. subscriber to another subscriber) will be denied. The map server and its generated policies are used to maintain the isolation between the different hosts/subscribers within the same subnet. 
     Because the policies can be generated as hosts join the enterprise fabric, if for some reason one or more hosts leave and re-join at a later time, new policies would be created for these hosts. This allows for coverage of scenarios where hosts are assigned different IP addresses thereby providing policies that are dynamic based on the circumstances associated with the enterprise fabric. 
     In step  440 , data packet transmission request can be provided. In particular, a host may provide a data packet to a switch so that it can be transmitted to another host within the enterprise fabric. 
     When the data packet is received by the switch, the switch communicates with the map server in step  450  in order to determine whether the transmission request/communication is appropriate. The policies generated in step  430  will detail which host (e.g. subscriber) which host (e.g. provider) can be communicated with. Based on the policies stored within the map server, the map server would provide an appropriate response in step  460 . 
     If the data packet is indeed between a source host defined as a subscriber and a destination host defined as a provider, the map server will provide confirmation that the transmission can continue. The data can then be transmitted between the two hosts. However, if the data packet is determined to attempt transmission between two hosts that are defined as subscribers within the same subnet, the map server would provide instructions for the data packet to be dropped (e.g. the transmission is not completed). 
     By using the embodiment described above in the example method  400 , an enterprise would be capable of having multiple sites associated with the same subnet allowing a headquarter site to manage and share resources/services with each of those sites efficiently. Furthermore, the map server and its dynamically generated policies would provide the isolation (and security) between the different sites/subscribers by preventing these sites from communicating amongst themselves. 
       FIG.  5 A  and  FIG.  5 B  illustrate examples of systems in accordance with some embodiments. The example systems can be implemented, for example, with respect to the provider/headquarter site and each of the subscribers/sites as illustrated in  FIG.  1    and  FIG.  2   . 
       FIG.  5 A  illustrates an example of a bus computing system  500  wherein the components of the system are in electrical communication with each other using a bus  505 . The computing system  500  can include a processing unit (CPU or processor)  510  and a system bus  505  that may couple various system components including the system memory  515 , such as read only memory (ROM)  520  and random access memory (RAM)  525 , to the processor  510 . The computing system  500  can include a cache  512  of high-speed memory connected directly with, in close proximity to, or integrated as part of the processor  510 . The computing system  500  can copy data from the memory  515 , ROM  520 , RAM  525 , and/or storage device  530  to the cache  512  for quick access by the processor  510 . In this way, the cache  512  can provide a performance boost that avoids processor delays while waiting for data. These and other modules can control the processor  510  to perform various actions. Other system memory  515  may be available for use as well. The memory  515  can include multiple different types of memory with different performance characteristics. The processor  510  can include any general purpose processor and a hardware module or software module, such as module 1  532 , module 2  534 , and module 3  536  stored in the storage device  530 , configured to control the processor  510  as well as a special-purpose processor where software instructions are incorporated into the actual processor design. The processor  510  may essentially be a completely self-contained computing system, containing multiple cores or processors, a bus, memory controller, cache, etc. A multi-core processor may be symmetric or asymmetric. 
     To enable user interaction with the computing system  500 , an input device  545  can represent any number of input mechanisms, such as a microphone for speech, a touch-protected screen for gesture or graphical input, keyboard, mouse, motion input, speech and so forth. An output device  535  can also be one or more of a number of output mechanisms known to those of skill in the art. In some instances, multimodal systems can enable a user to provide multiple types of input to communicate with the computing system  500 . The communications interface  540  can govern and manage the user input and system output. There may be no restriction on operating on any particular hardware arrangement and therefore the basic features here may easily be substituted for improved hardware or firmware arrangements as they are developed. 
     The storage device  530  can be a non-volatile memory and can be a hard disk or other types of computer readable media which can store data that are accessible by a computer, such as magnetic cassettes, flash memory cards, solid state memory devices, digital versatile disks, cartridges, random access memory, read only memory, and hybrids thereof. 
     As discussed above, the storage device  530  can include the software modules  532 ,  534 ,  536  for controlling the processor  510 . Other hardware or software modules are contemplated. The storage device  530  can be connected to the system bus  505 . In some embodiments, a hardware module that performs a particular function can include a software component stored in a computer-readable medium in connection with the necessary hardware components, such as the processor  510 , bus  505 , output device  535 , and so forth, to carry out the function. 
       FIG.  5 B  illustrates an example architecture for a chipset computing system  550  that can be used in accordance with an embodiment. The computing system  550  can include a processor  555 , representative of any number of physically and/or logically distinct resources capable of executing software, firmware, and hardware configured to perform identified computations. The processor  555  can communicate with a chipset  560  that can control input to and output from the processor  555 . In this example, the chipset  560  can output information to an output device  565 , such as a display, and can read and write information to storage device  570 , which can include magnetic media, solid state media, and other suitable storage media. The chipset  560  can also read data from and write data to RAM  575 . A bridge  580  for interfacing with a variety of user interface components  585  can be provided for interfacing with the chipset  560 . The user interface components  585  can include a keyboard, a microphone, touch detection and processing circuitry, a pointing device, such as a mouse, and so on. Inputs to the computing system  550  can come from any of a variety of sources, machine generated and/or human generated. 
     The chipset  560  can also interface with one or more communication interfaces  590  that can have different physical interfaces. The communication interfaces  590  can include interfaces for wired and wireless LANs, for broadband wireless networks, as well as personal area networks. Some applications of the methods for generating, displaying, and using the technology disclosed herein can include receiving ordered datasets over the physical interface or be generated by the machine itself by the processor  555  analyzing data stored in the storage device  570  or the RAM  575 . Further, the computing system  550  can receive inputs from a user via the user interface components  585  and execute appropriate functions, such as browsing functions by interpreting these inputs using the processor  555 . 
     It will be appreciated that computing systems  500  and  550  can have more than one processor  510  and  555 , respectively, or be part of a group or cluster of computing devices networked together to provide greater processing capability. 
     For clarity of explanation, in some instances the various embodiments may be presented as including individual functional blocks including functional blocks comprising devices, device components, steps or routines in a method embodied in software, or combinations of hardware and software. 
     In some embodiments the computer-readable storage devices, mediums, and memories can include a cable or wireless signal containing a bit stream and the like. However, when mentioned, non-transitory computer-readable storage media expressly exclude media such as energy, carrier signals, electromagnetic waves, and signals per se. 
     Methods according to the above-described examples can be implemented using computer-executable instructions that are stored or otherwise available from computer readable media. Such instructions can comprise, for example, instructions and data which cause or otherwise configure a general purpose computer, special purpose computer, or special purpose processing device to perform a certain function or group of functions. Portions of computer resources used can be accessible over a network. The computer executable instructions may be, for example, binaries, intermediate format instructions such as assembly language, firmware, or source code. Examples of computer-readable media that may be used to store instructions, information used, and/or information created during methods according to described examples include magnetic or optical disks, flash memory, USB devices provided with non-volatile memory, networked storage devices, and so on. 
     Devices implementing methods according to these disclosures can comprise hardware, firmware and/or software, and can take any of a variety of form factors. Some examples of such form factors include general purpose computing devices such as servers, rack mount devices, desktop computers, laptop computers, and so on, or general purpose mobile computing devices, such as tablet computers, smart phones, personal digital assistants, wearable devices, and so on. Functionality described herein also can be embodied in peripherals or add-in cards. Such functionality can also be implemented on a circuit board among different chips or different processes executing in a single device, by way of further example. 
     The instructions, media for conveying such instructions, computing resources for executing them, and other structures for supporting such computing resources are means for providing the functions described in these disclosures. 
     Although a variety of examples and other information was used to explain aspects within the scope of the appended claims, no limitation of the claims should be implied based on particular features or arrangements in such examples, as one of ordinary skill would be able to use these examples to derive a wide variety of implementations. Further and although some subject matter may have been described in language specific to examples of structural features and/or method steps, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to these described features or acts. For example, such functionality can be distributed differently or performed in components other than those identified herein. Rather, the described features and steps are disclosed as examples of components of systems and methods within the scope of the appended claims.