Updating link state information in networks

Assignee: Digital Equipment Corp

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Filing: 1990-12-28

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Granted: —

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Expires: 2010-12-28

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Abstract

Abstract Methods and apparatus for sending link state information through a network of nodes interconnected by links. Link state packets (LSPs) are fragmented, and the fragments are sent individually through the network. The network routers may update their link state databases and perform routing without having to receive and reassemble all of the fragments. When the state of a link changes, only an amended version of the fragment affected by the change is transmitted. In another aspect, the invention features methods and apparatus for transmitting LSP sequence number information through the network. First, the link state packets being stored by a node are ordered alphabetically according to their source node. Next, a range of this order is selected and placed in a summary packet indicating the boundaries of the selected range and, for each link state packet in the selected range, the source and sequence number of the stored link state packet.

Inventors

👤 Radia J. Perlman
👤 Charles W. Kaufman
👤 Ross Callon

Bibliographic Details

Application Number —

Jurisdiction EP

Data Source google_patents

Last Synchronized 2026-10-25 04:21

CPC Classifications

H; H04; H04L; H04L45/00; H04L45/02; H04L69/00

Claims Analysis

Total Claims: 4

Claim 1

Independent Claim 232 words

A method for updating, at a first node of a network of nodes interconnected by links, stored information used for routing packets at said first node, comprising a. sending at least one link state packet to said first node, said packet indicating the state of one or more links connected to a given node in said network, b. attempting, at said first node, to derive from the packet or packets sent in step (a), the states of said links, and c. where the states of fewer than all of the links connected to said given node are derived in step (b), updating said stored information used for routing packets using the derived link states, d. where a link connected to said given node changes from a first state to a second state, determining whether the first state of said link was indicated in a previously sent packet, e. where the first state of said link was indicated in a previous packet, sending to said first node only an amended version of said previous packet, said amended version indicating that said changed link is in said second state, and storing an indicator indicating the amendments made to said previous packet, and f. where the first state of said link was not indicated in a previous packet, sending to said first node a packet indicating that said changed link is in said second state.

Claim 2

Dependent Claim 14 words

The method of claim 1, wherein said indicator is stored in said given node.

Claim 3

Dependent Claim 60 words

The method of claim 1, further comprising g. where said changed link subsequently changes from said second state back to said first state, retrieving said stored indicator, h. forming a twice amended version of said previous packet by removing the amendments indicated by said indicator, and i. sending only said twice amended version of said packet to said first node.

Claim 4

Dependent Claim 105 words

The method of claim 3, wherein said first state is an operative state and said second state is an inoperative state, each link state packet indicates that a link connected to said given node is operative by identifying one or more nodes that are connected to the operative link, and indicates that a link connected to said given node is inoperative by omitting identification of one or more nodes that are connected to the inoperative link, and said indicator comprises a field for identifying a node and a flag bit for indicating the operability of the link connecting the identified node to said given node.

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