Cisco Technology, Inc.

James L Ng

Alvaro E Retana

Yi Yang

Steven Edward Moore

Russell Ivan White

Timothy M Gage

Donnie Van Savage

Thuan Van Tran

Alfred C Lindem, Iii

Abhay Kumar Roy

Syed Khalid Raza

Sina Mirtorabi

Heidi H Ou

Steven Vincent Luong

Donald Earl Slice, Jr

Gerald Redwine

Kevin M Eckhardt

Scott R Sturgess

Brian Eliot Weis

David Anthony Cook

Donald Slice

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 an example embodiment, a method and system is provided to determine and advertise a route advertisement in a reactive routing environment. In response to receiving a network address query with respect to a destination address at a routing device, an aggregate value, e.g. an address prefix, is determined and advertised in reply to the network address query. Determining of the aggregate value may comprise identifying within a range of network addresses represented by the aggregate value respective addresses for which the routing device does not have reachability information. The routing device may send address queries with respect to the identified addresses, to determine reachability via the routing device of those addresses. The aggregate value may be advertised conditional upon determining that a percentage of addresses within the corresponding range that can be reached via the routing device satisfies a predefined minimal coverage value.

Determining a route advertisement in a reactive routing environment

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

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.

In an example embodiment, a method is provided. In this method, a network address query is received. A first network address of a known apparatus is retrieved from a routing table, in response to the network address query. A second network address may be determined based upon the network address query, the second network address having a smaller bit length than the first network address. An aggregate value may be advertised that represents a range of reachable network addresses, the range of reachable network addresses including the second network address.

Determining an optimal route advertisement in a reactive routing environment

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.

A router identifies transit links and non-transit links. Only the non-transit links are advertised as routes to adjacent routers, thereby protecting the transit links from edge traffic which terminates on a network on one of the transit links. In another aspect of the invention, an administrative whitelist supplements the routes which identify the transit link network routes. In another aspect of the invention, a method for advertising routes identifies entries in a router table as broadcast or point-to-point. Only the router table entries for point-to-point links which are not transit or broadcast links that are not for a neighboring router are advertised, whereas the point-to-point transit links or broadcast transit links are advertised as transit links if an administrative whitelist is enabled.

Protection of transit links in a network

Disclosed are methods and apparatus for flooding link state packets or packet data units (LSP's) from a first node to one other LSP receiving node, where the LSP's are flooded in an order that is related to relative costs of various paths emanating from the first node. That is, the first node sends its own LSP first since the first node has no cost relative to itself. The first node then sends other LSP's that are associated with a plurality of other LSP sending nodes that have previously flooded their LSP's to the first node. These other LSP's are sent by the first node to the other LSP receiving node in an order related to the relative costs associated with the paths from the first node to each of the other LSP sending nodes which had previously sent the other LSP's to the first node.

Method and apparatus for flooding link state packets to achieve faster convergence

In one embodiment, a method includes receiving a first link state initiation (HELLO) message from a first neighboring router. The HELLO message requests that a recipient node send a unique identifier for itself in a link state routing protocol. In response to receiving the first HELLO message, a first response message is sent that includes a first identifier from an identifier pool. The identifier pool contains for a local node a plurality of network identifiers that are unique among all nodes in the network that uses the link state routing protocol. A second HELLO message is received from a different second neighboring router. In response to receiving the second HELLO message, a second response message is sent that includes a different second identifier from the identifier pool.

Growing community of inventors

Mebane, NC, United States of America

James L Ng