Cisco Technology, Inc.

Timothy M Gage

Yi Yang

Alvaro E Retana

James L Ng

Alfred C Lindem, Iii

Abhay Kumar Roy

Syed Khalid Raza

Sina Mirtorabi

Donnie Van Savage

Steven Edward Moore

Russell Ivan White

Thuan Van Tran

Roy Abhay

In one embodiment, a first router determines whether an interface coupling the first router to one or more second routers is transit-only. When the interface is transit-only, the first router generates an Open Shortest Path First (OSPF) Link State Advertisement (LSA) that includes an address for the interface and a designated network mask. The designated network mask operates as a transit-only identification that indicates the address should not be installed in a Routing Information Base (RIB) upon receipt of the OSPF LSA at the one or more second routers. When the network is not transit-only, the first router generates an OSPF LSA that includes the address for the interface but does not include the designated network mask, to permit installation of the address in a RIB upon receipt of the OSPF LSA at the one or more second routers.

Apparatus and method to hide transit only multi-access networks in OSPF

Present disclosure relates to methods for preparing BGP update messages for transmission and processing received update messages. The methods are based on grouping path attributes common to a plurality of IP address prefixes into respective sets identified with respective set identifiers and, instead of duplicating path attributes in each BGP update message, including a respective identifier referring to a certain set of path attributes provided in an earlier BGP update message when sending subsequent update messages. Grouping of path attributes into individual sets associated with respective identifiers provides significant advantages by enabling re-use of the results of previous processing on both the sending and receiving sides associated with transmission of BGP update messages. In addition, such an approach limits the amount of information transmitted in the control plane because duplicate sets of path attributes may only be transmitted once and merely be referred to in subsequent update messages.

Attribute SET_ID in border gateway protocol

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In one embodiment, a first router determines whether a network coupling the first router to one or more second routers is transit-only, wherein transit-only indicates connecting only routers to provide for transmission of data from router to router. When the network is transit-only, the first router generates an Open Shortest Path First (OSPF) Link State Advertisement (LSA) that includes an address for the network and a designated network mask. The designated network mast operates as a transit-only identification that indicates the address should not be installed in a Routing Information Base (RIB) upon receipt of the OSPF LSA at the one or more second routers. When the network is not transit-only, the first router generates an OSPF LSA that includes the address for the network but does not include the designated network mask, to permit installation of the address in a RIB upon receipt of the OSPF LSA at the one or more second routers.

In one embodiment, a Link State Advertisement (LSA) is received from a first router in a network at a second router in the network. The LSA advertises an address of an interface of the first router. The second router determines whether the LSA includes a transit-only identification that indicates the interface of the first router is a transit-only interface. If the LSA does not include a transit-only identification, the second router installs the advertised address of the interface of the first router in a Router Information Base (RIB) of the second router. If the LSA does include a transit-only identification, the second router declines to install the advertised address of the interface of the first router in the RIB of the second router.

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 for hiding transit-only interfaces in a network. When a routing system is advertising a transit-only interface, the advertisement is marked to indicate the address is a transit-only interface. A routing system receives the advertisement and detects the identifier of the transit-only interface and does not store the address in the Router Information Base of the routing system.

In one embodiment, information is signaled between aggregating routers indicating the components of aggregated addresses. This information is used to dynamically leak, or deaggregate, specific parts of the aggregated address space to reduce sub-optimal routing and possibly prevent routing black holes from occurring in a network.

Technique to automatically deaggregate an optimum set to prevent suboptimal routing or routing failures within a link state flooding domain

The present invention describes a method and apparatus to ensure bi-directional connectivity between neighbor network elements in distance-vector protocol (e.g., EIGRP). The method further defines the dampening of neighbors that cannot establish a bi-directional connectivity. When a router receives an unreliable packet from a neighbor, the router adds the neighbor in neighbor table by gradually developing the reliability of the neighbor. First, the router adds neighbor's address into a dampening table and a 'neighbor pending' table. The router establishes a reliable communication with the neighbor. If the router cannot establish the reliable communication with the neighbor, the router dampens the neighbor and removes neighbor's address from 'neighbor pending' table. When the router establishes a reliable communication with the neighbor, the router &#x2018;promotes&#x2019; the neighbor to the neighbor table. The router does not &#x2018;advertise&#x2019; neighbor in its neighbor table until the neighbor is &#x2018;promoted&#x2019; to the neighbor table.

Method of establishing bi-directional connectivity of a network element in a network

A method for communicating packets in a network environment is provided that includes receiving a first and a second packet and determining if the second packet is substantially similar to the first packet. If the second packet is received during a predetermined time interval, then the first packet may be communicated to a next destination.

Growing community of inventors

Durham, NC, United States of America

Timothy M Gage