Cisco Technology, Inc.

Thuan Van Tran

Donnie Van Savage

Yi Yang

James L Ng

Russell Ivan White

Liem Hong Nguyen

Donald Earl Slice, Jr

Donald Slice

Alvaro E Retana

Steven Edward Moore

Timothy M Gage

A system and method for facilitating connecting a switch to a network to improve network performance. In an illustrative embodiment, the system includes a first module for determining when the switch is initially connected to a network and providing a signal in response thereto. A second module selectively forms adjacencies with peers of the switch in response to the signal and based on one or more predetermined parameters. In a more specific embodiment, the switch is a router or Layer-3 (L3) switch. The one or more predetermined parameters include a load factor, values pertaining to capabilities of a processor included in the router, bandwidth capabilities of the interface and/or the router, internal router queue counts, and so on. The router employs a routing protocol such as Enhanced Interior Gateway Routing Protocol (EIGRP). The second module throttles and adjacency-formation rate based on the predetermined parameters.

System and method for enhancing network stability by selectively controlling adjacency formation

Techniques are disclosed for synchronizing a database related to a first node in a network with multiple nodes. Each node includes a database different from a database on a different node. An inquiry control message is sent to each node in a candidate set of one or more nodes on the network, which are different from the first node. In response to the inquiry control message, the first node receives a first set of one or more messages from a particular node different from the first node. The first set indicates a portion from the database of the particular node. The portion is relevant for the first node. A particular portion of a first database for the first node is derived from the first set of messages. The particular portion is less than all of the first database. These techniques allow the first node to derive its full database from multiple adjacent nodes.

Synchronizing portions of a database with different databases on different nodes of a network

A system for optimizing the performance of a network. In an illustrative embodiment, the system includes a memory containing one or more data structures data structures. A first module determines transit-only information. A second module selectively omits the transit-only information from the one or more data structures. In a more specific embodiment, the one or more data structures include one or more tables. The transit-only information includes interface Internet Protocol (IP) addresses associated with network interfaces that are transit-only interfaces. The route information may include network topology information. The one or more tables may include a network topology table. Plural routers positioned in the network incorporate one or more instances of the system. The routers may employ one or more routing protocols, such as include Enhanced Interior Gateway Routing Protocol (EIGRP) or Routing Information Protocol (RIP).

System and method for improving network performance and security by controlling topology information

A system and method for enhancing the behavior of a network. In an illustrative embodiment, the network includes a distribution router and plural additional routers connected to the distribution router. The system includes a first module that is adapted to characterize the additional routers as stub routers or non-stub routers and then to provide a signal in response thereto. A second module selectively queries non-stub routers for route information and does not query stub routers for the route information. In a more specific embodiment, the second module includes a unicast module for selectively unicasting queries to the non-stub routers. A multicast module selectively multicasts queries to the non-stub routers via a modified conditional-receive algorithm.

System and method for improving network performance by controlling stub-routing behavior

Techniques for synchronizing routing data include determining whether conditions are satisfied for one-way transfer with an adjacent router. If it is determined that conditions are satisfied for one-way transfer of routing table data with the adjacent router, then a refresh-notice message is sent from the initiating router to the adjacent router. The refresh-notice message includes data that indicates a particular direction for transfer of routing table data. If the particular direction is inbound, then a copy of an adjacent routing table is received without sending a copy of the initiating router's own routing table. If the particular direction is outbound, then a copy of the own routing table is sent without receiving a copy of the adjacent routing table.

Techniques for one-way synchronization of routing information among intermediate nodes

Techniques for sending data in a packet-switched communications network include determining multiple subsets of adjacent network nodes of the network. The adjacent network nodes communicate without intervening network nodes with a particular network node through an interface on the particular network node. Each subset includes multiple adjacent network nodes. Subset definition data is sent through the interface. The subset definition data indicates which adjacent network nodes belong to which subset. Data for fewer than all adjacent network nodes in all subsets are sent by including, in a multicast data packet sent over the interface with a multicast destination address, subset identifier data that indicates a particular subset. When such data is received by a node, it is discarded unless the subset identifier matches the receiving node's subset identifier. Among other effects, this allows routing messages to be more efficiently sent to better performing neighboring network nodes.

Techniques for distributing information using multicast subsets

A static neighbor configured network device is configured with a static neighbor feature including a static neighbor list of network devices. The static neighbor configured network device is in a network segment that includes a dynamically configured network device. The static neighbor configured network device receives a multicast packet from the dynamically configured network device. It is determined if the dynamically configured network device is included in the static neighbor list of the static neighbor configured network device. The multicast packet is accepted if the dynamically configured network device is found in the neighbor list for the static neighbor configured network device. Also, adjacency for the static neighbor configured network device is not lost with any other currently adjacent network devices when the multicast packet is received.

Techniques to support asymmetrical static/dynamic adjacency in routers

Techniques for sending routing data include sending first routing data in a first multicast packet to a number N of adjacent nodes. It is determined whether different routing data is ready to be sent in a different multicast packet. If so, then a number M of adjacent nodes from which acknowledgment messages have been received, and whether M exceeds a threshold, is determined. If so, then a Conditional-Receive (CR) method is invoked in which a multicast message is sent which identifies each of a number L=N&#x2212;M of laggard adjacent nodes. The laggard adjacent nodes are thus notified to ignore the different multicast packet. If it is determined that M does not exceed the threshold, then additional acknowledgement messages are received while waiting until M does exceed the threshold before the CR method is invoked. The threshold is greater than or equal to 1.

Techniques for distributing routing information using multicasts

A technique efficiently notifies EIGRP neighbors when destroying adjacencies in a computer network. A goodbye notification packet is provided that enables an EIGRP router to inform one or more of its neighbors of its intention to destroy their existing adjacencies. The goodbye notification packet comprises an EIGRP packet header with variable-length fields embodied as an appended goodbye attribute. The appended goodbye attribute is illustratively tagged according to a TLV encoding format that defines a new type (T) field called 'a goodbye' having a predetermined type that distinguishes it from a conventional EIGRP Hello packet. A value (V) field of information conveyed within the goodbye attribute contains a list of neighbor (peer) identifiers (IDs). The peer IDs on this list instruct those neighbor routers to 'go away' so that their adjacencies can be destroyed.

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Cary, NC, United States of America

Thuan Van Tran