Browse Prior Art Database

Source Base Flow Reduction in Topology Updates

IP.com Disclosure Number: IPCOM000110000D
Original Publication Date: 1992-Oct-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 3 page(s) / 130K

Publishing Venue

IBM

Related People

Cidon, I: AUTHOR [+3]

Abstract

This article proposes methods to reduce the number of topology database records (where a record is, e.g., information about one link) sent during the initial exchange of information between nodes, at the time the link between them starts to participate in updates dissemination.

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Source Base Flow Reduction in Topology Updates

       This article proposes methods to reduce the number of
topology database records (where a record is, e.g., information about
one link) sent during the initial exchange of information between
nodes, at the time the link between them starts to participate in
updates dissemination.

      In many networks each local node is responsible for determining
the bandwidth utilization of its adjacent links, for determining when
to inform remote nodes of changes in utilization, and for
distributing this information to remote nodes.  Distributing this
information is called utilization broadcast/update.  A similar task
is the topology update where the information about the active and
inactive links is distributed.  The utilization and the status of the
links are examples of types of information that are local, that is,
each piece of it (e.g., a link) belongs to a certain node, who is
aware of the changes in it.  An additional example is the userids of
users on each of the nodes.  Let us call the general task of updating
information local information update.  In this article we explain the
flow reduction in the topology  update task.  The solution to other
kinds of local information update is very similar.

      The objective of topology update is to maintain a consistent
view of the topology of the network in all the network nodes in the
network for the purposes of finding key services, maintaining
current network state information and computing good routes through
the network.

      Topology updates are triggered whenever a node senses a change
in the status (e.g., failure or recovery) of an adjacent link.  In
most topology update protocol the sensing node numbers each change
with increasing sequence numbers, and broadcast the changes.  Such a
broadcast reaches the nodes that are currently connected to this
node.  Sometimes not every link is designated to carry such
broadcasts.  In this case the nodes that are considered connected to
the broadcasting node are only those who are connected using
broadcast carrying links.  For example, if the broadcast is carried
over trees, then only the nodes in the same tree as the broadcast
source receive the broadcast.

      At later times the connected component may change.  This may
happen when a new link joins the broadcast carrying sets of links
(e.g., a new link recovers, or is defined as a tree link) or when a
link leaves this set (e.g., fails).

      When a new link joins, an initial exchange of topology
information takes place between the link's endpoints.  Typically they
exchange their whole topology database.

      Alternatively, each may send the other the information it did
not send the other previously. Even in this case, it may happen that
the other endpoint has received this information previously over
another link.

      In this article we reduce the cost of such cases.
Flow Reduction

      Pr...