Abstract: A routing system for implementing a service and topology exchange protocol (STEP) comprises a primary STEP server configured to maintain a STEP repository and a plurality of routers, each router including a STEP client in communication with the primary STEP server. The STEP client of each router is configured to transmit, using the service and topology exchange protocol, service and topology state information for at least one route or service available through the router to the primary STEP server for storage in the STEP repository.

Abstract: A routing system for providing multicast access control includes a plurality of routers including a multicast source router and a plurality of multicast receiver routers, the plurality of routers providing a multicast service, wherein the routers are configured to enforce multicast access control policies for the multicast service including a receiver access policy that controls which multicast receivers are allowed to receive packets from the multicast service and a sender access policy that controls which multicast sources are allowed to send packets to the multicast service for distribution to the multicast receivers.

Abstract: A router advertises an aggregated service or route that can be evaluated by other routers as a unitary segment rather than as a group of individual links/paths associated with the aggregated service or route. The aggregated service or route can be based on service and topology state information received from one or more other routers and can be advertised with the router as the nexthop for the aggregated service or route. The router can advertise an aggregated metric for the aggregated service or route for use in such evaluation. An aggregated route can be associated with different aggregated metrics for different services.

Abstract: A routing system for distributing multicast routing information for a multicast service includes a plurality of routers including a multicast source router and a plurality of multicast receiver routers, the plurality of routers providing a multicast service, wherein the routers are configured to exchange multicast information associated with the multicast service including identification of multicast sources and the multicast receivers.

Abstract: A routing system for routing packets for a route or service comprises a plurality of routers including a source router, wherein the source router is configured to receive, using a service and topology exchange protocol, service and topology state information from a STEP repository for at least one other router based on configured relationships between routers; determine a first path to a destination for a route or service based on the service and topology state information, the first path including an ordered list of successive routers to receive a packet associated with the route or service starting with a first successive router and ending with a destination router; and transmit a packet toward the first successive router with first metadata including a list of at least one remaining router of the ordered list of routers to receive the packet associated with the route or service.

Abstract: Routing packets by a router involves establishing a first flow configured for forwarding the packets from a first ingress interface to a first egress interface of the router; determining a condition to modify the first flow; deactivating the first flow; establishing a second flow configured for forwarding the packets from at least one of (1) the first ingress interface to a second egress interface, (2) a second ingress interface to the first egress interface, or (3) a second ingress interface to a second egress interface; and activating the second flow.

Abstract: A packet routing method and apparatus for managing packets of a bi-directional session between a first node and a second node in an IP network receives a mid-stream packet at an intermediate node. The intermediate node is not part of the bi-directional session. Next, the method identifies the bi-directional session (“identified session”) from which the mid-stream packet originated. The identified session includes a bi-directional path between the first node and the second node, while the bi-directional path includes a plurality of nodes for bi-directionally forwarding packets between the first node and the second node. The method then directs that one or more packets of the identified session be routed to at least one of the plurality of nodes of the identified session.

Abstract: Two nodes in a communication system exchange link monitoring protocol messages including special metadata that allows each node to determine the status of source NAT on communication links to and from the other node, e.g., if source NAT is present on the communication link, or if there is a change in source NAT configuration (e.g., from enabled to disabled, from disabled to enabled, or from one translation to another translation). The special metadata also allows true source information (e.g., source address and source port number) to be conveyed between nodes even in the presence of source NAT, because the source NAT device does not change the metadata in the message because the metadata is considered to be part of the message payload. In certain exemplary embodiments, knowledge regarding the presence of source NAT devices as well as the true source information conveyed through the source NAT devices via the special metadata can be used in the context of “stateful” routing.

Abstract: In exemplary embodiments of the present invention, special metadata is added to link monitoring protocol messages exchanged by pairs of adjacent nodes to allow such nodes to detect communication link failures and determine whether the failure affects an incoming communication link or an outgoing communication link. The link monitoring protocol messages may be augmented BFD messages.

Abstract: A packet routing method and apparatus for managing packets of a bi-directional session between a first node and a second node in an IP network receives a mid-stream packet at an intermediate node. The intermediate node is not part of the bi-directional session. Next, the method identifies the bi-directional session (“identified session”) from which the mid-stream packet originated. The identified session includes a bi-directional path between the first node and the second node, while the bi-directional path includes a plurality of nodes for bi-directionally forwarding packets between the first node and the second node. The method then directs that one or more packets of the identified session be routed to at least one of the plurality of nodes of the identified session.

Abstract: Embodiments of the present invention provide for continuity of “stateful” routing sessions in the presence of source network address translation (NAT). Specifically, a stateful routing session may be moved from one routing path to another routing path, e.g., due to a routing change in the communication network, where the routing paths have different source NAT status. For example, the stateful routing session may be moved from a path having no source NAT to a path having source NAT, from a path having source NAT to a path having no source NAT, or from paths having different source network address translations. When a stateful routing session is moved from an existing routing path to a new routing path, the routers detect the routing change based on the change in source NAT status using a special link monitoring protocol.

Abstract: A router is specially configured to implement a bilateral TCP state machine to monitor the status of TCP sessions based on TCP sequence numbers in both forward session packets and return session packets received by the router for a TCP bi-flow session. Among other things, the router may determine the status of a TCP session, for example, based on statistical information such as the number or rate of errors detected (e.g., the number of dropped packets, duplicated packets, out-of-sequence packets, and/or out-of-window packets). Each router is typically configured to collect and store status information and optionally also to use the status information in making intelligent routing decisions, such as, for example, deciding whether or not to forward a particular packet, deciding whether to reconfigure a bi-flow routing session, or updating routing table information used for routing packets.

Abstract: A router is specially configured to implement a bilateral TCP state machine to monitor the status of TCP sessions based on TCP sequence numbers in both forward session packets and return session packets received by the router for a TCP bi-flow session. Among other things, the router may determine the status of a TCP session, for example, based on statistical information such as the number or rate of errors detected (e.g., the number of dropped packets, duplicated packets, out-of-sequence packets, and/or out-of-window packets). Each router is typically configured to collect and store status information and optionally also to use the status information in making intelligent routing decisions, such as, for example, deciding whether or not to forward a particular packet, deciding whether to reconfigure a bi-flow routing session, or updating routing table information used for routing packets.

Abstract: Two nodes in a communication system exchange link monitoring protocol messages including special metadata that allows each node to determine the status of source NAT on communication links to and from the other node, e.g., if source NAT is present on the communication link, or if there is a change in source NAT configuration (e.g., from enabled to disabled, from disabled to enabled, or from one translation to another translation). The special metadata also allows true source information (e.g., source address and source port number) to be conveyed between nodes even in the presence of source NAT, because the source NAT device does not change the metadata in the message because the metadata is considered to be part of the message payload. In certain exemplary embodiments, knowledge regarding the presence of source NAT devices as well as the true source information conveyed through the source NAT devices via the special metadata can be used in the context of “stateful” routing.

Abstract: In exemplary embodiments of the present invention, special metadata is added to link monitoring protocol messages exchanged by pairs of adjacent nodes to allow such nodes to detect communication link failures and determine whether the failure affects an incoming communication link or an outgoing communication link. The link monitoring protocol messages may be augmented BFD messages.

Abstract: Embodiments of the present invention provide for continuity of “stateful” routing sessions in the presence of source network address translation (NAT). Specifically, a stateful routing session may be moved from one routing path to another routing path, e.g., due to a routing change in the communication network, where the routing paths have different source NAT status. For example, the stateful routing session may be moved from a path having no source NAT to a path having source NAT, from a path having source NAT to a path having no source NAT, or from paths having different source network address translations. When a stateful routing session is moved from an existing routing path to a new routing path, the routers detect the routing change based on the change in source NAT status using a special link monitoring protocol.

Abstract: Routing packets by a router involves establishing a first flow configured for forwarding the packets from a first ingress interface to a first egress interface of the router; determining a condition to modify the first flow; deactivating the first flow; establishing a second flow configured for forwarding the packets from at least one of (1) the first ingress interface to a second egress interface, (2) a second ingress interface to the first egress interface, or (3) a second ingress interface to a second egress interface; and activating the second flow.

Abstract: In exemplary embodiments of the present invention, a router determines whether or not to establish a stateful routing session based on the suitability of one or more candidate return path interfaces. This determination is typically made at the time a first packet for a new session arrives at the router on a given ingress interface. In some cases, the router may be configured to require that the ingress interface be used for the return path of the session, in which case the router may evaluate whether the ingress interface is suitable for the return path and may drop the session if the ingress interface is deemed by the router to be unsuitable for the return path. In other cases, the router may be configured to not require that the ingress interface be used for the return path, in which case the router may evaluate whether at least one interface is suitable for the return path and drop the session if no interface is deemed by the router to be suitable for the return path.

Abstract: A method for resolving split conditions in a port-extended network comprises receiving first information indicative of a first MAC address of a first controller on a first fabric link and second information indicative of a second MAC address of a second controller on a second fabric link. The method may also include determining that the first MAC address differs from the second MAC address and responsively determining that one of the first MAC address or the second MAC address was previously associated with a primary controller of the port-extended network. One of the first controller or the second controller is designated as the primary controller of the port-extended network based on the determination that one of the first MAC address or the second MAC address was previously associated with the primary controller.