Browse Prior Art Database

Hierarchical Path Selection in Multi-Stage Networks

IP.com Disclosure Number: IPCOM000099703D
Original Publication Date: 1990-Feb-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 2 page(s) / 77K

Publishing Venue

IBM

Related People

Barker, TN: AUTHOR [+5]

Abstract

Disclosed is a method used in multi-stage networks to overcome their major disadvantage of "blocking", i.e., a connection might not be able to be formed between two IDLE devices because there is no path available in the network. The method relies on alternate paths within the network and a hierarchical means of selecting which alternate path to use to permit a non-blocked path to be found by "rearrangeability" - the act of trying different alternate paths until a connection is established. This method works well for unbuffered networks which reject messages for retry when blockage occurs.

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Hierarchical Path Selection in Multi-Stage Networks

       Disclosed is a method used in multi-stage networks to
overcome their major disadvantage of "blocking", i.e., a connection
might not be able to be formed between two IDLE devices because there
is no path available in the network. The method relies on alternate
paths within the network and a hierarchical means of selecting which
alternate path to use to permit a non-blocked path to be found by
"rearrangeability" - the act of trying different alternate paths
until a connection is established.  This method works well for
unbuffered networks which reject messages for retry when blockage
occurs.

      This article presents a new method and implementation for
determining which ALTERNATE PATH is chosen initially and on each
successive retry.  Simulation studies of unbuffered memory networks
have shown that two types of network traffic exist:  "Hot" and
"Cold", "Cold" being random memory traffic and "Hot" being
concentrated memory traffic to one particular memory location or
module.  The studies found that "Cold" traffic gets through the
network with a very high rate of success on one of the first several
tries. However, "Hot" traffic retry attempts clog the network because
they increase the contention at the memory, which decreases the
likelihood of success with additional retries. A solution lies in the
use of hierarchical networks composed of at least two different
networks with at least one dedicated to "Cold" traffic and at least
one dedicated to "Hot" traffic.  By separating the two types of
traffic, it has been shown by simulation that both types of traffic
are then routed throu...