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Method of Detecting Topology Broadcast Loops in Advanced Peer-to-Peer Networking

IP.com Disclosure Number: IPCOM000117376D
Original Publication Date: 1996-Feb-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 82K

Publishing Venue

IBM

Related People

Hefel, T: AUTHOR [+2]

Abstract

Disclosed is a function that detects all known types of Topology Database Update (TDU) broadcast loops that may occur in Advanced Peer-to-Peer Networking (APPN) networks. The function detects this kind of loop, stops it from continuing, and issues an Alert indicating the network problem causing this TDU loop.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Method of Detecting Topology Broadcast Loops in Advanced Peer-to-Peer
Networking

      Disclosed is a function that detects all known types of
Topology Database Update (TDU) broadcast loops that may occur in
Advanced Peer-to-Peer Networking (APPN) networks.  The function
detects this kind of loop, stops it from continuing, and issues an
Alert indicating the network problem causing this TDU loop.

      Another common term used to describe a TDU loop is a TDU war.
A TDU war occurs when two or more network nodes continuously contend
over the contents of the same resource records in their Topology
Databases (TDB).  This contention causes TDUs to be continuously
broadcast into the network, resulting in a reduction (usually
significant) in the bandwidth available to the network.  Other than
the drop in available bandwidth, the war does not produce any
tangible signs for network managers to detect (i.e., sessions do not
fail, Alerts are not issued, etc.).  Because there are many reasons
that cause available network bandwidth to decrease, therefore, a TDU
war is very difficult for operators to detect.  It is possible for
these wars to continue for days before they are properly discovered
and stopped.

      To dynamically detect a TDU war, a Network Node (NN) first
creates a resource update counter whenever another NN broadcasts a
resource update in a TDU for a resource owned by the local NN, that
contains new or different information compared to the local copy of
that resource record.  This counter represents the number of times
another node has tried to modify this resource record.  A counter for
a resource record is created and initialized to one the first time
all of the following conditions occur:
  1.  The resource's record is present within an input TDU.
  2.  The resource is owned by the NN receiving the TDU.
  3.  Either the resource record's Resource Sequence Number (RSN)
       in the TDU is greater than the RSN of the corresponding
       resource record in the NN's TDB OR the RSN in the TDU is
       equal to the RSN of the resource record in the NN's TDB and
       the contents of the resource records are not identical.

      A counter is maintained for each resource in which these
conditions are true, and is incremented by one for every further
attempt to modif...