Browse Prior Art Database

Path Selection in Multi-Stage Networks Based On Availability

IP.com Disclosure Number: IPCOM000101466D
Original Publication Date: 1990-Aug-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 70K

Publishing Venue

IBM

Related People

Olnowich, HT: AUTHOR

Abstract

It is common for multi-stage networks to provide alternate paths for passing messages between devices. This article presents a new method and implementation for determining which ALTERNATE PATH to choose, thus increasing the probability of quickly finding a connecting path to the desired device.

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Path Selection in Multi-Stage Networks Based On Availability

       It is common for multi-stage networks to provide
alternate paths for passing messages between devices.  This article
presents a new method and implementation for determining which
ALTERNATE PATH to choose, thus increasing the probability of quickly
finding a connecting path to the desired device.

      Disclosed is a method that allows transmitting devices to make
an intelligent selection of which ALTERNATE PATH to use based on
AVAILABILITY.  This results in selecting an alternate path whose
first stage is not blocked or BUSY. The ALTERNATE PATH selected in
this manner can be blocked at subsequent stages and retransmission
over a different ALTERNATE PATH is permitted.  However, this method
makes the first stage non-blocking, and by nature the last crossbar
stage of multi- stage networks is non-blocking.  Thus, blockage is
virtually eliminated from both the first and last stages, making a
two-stage network as efficient as a one large single-stage crossbar.
Also, the efficiency of multi-stage networks which incorporate more
than 2 stages is increased because the blocking is restricted to only
the middle stages of the network.

      The first stage of a multi-stage network that implements m
ALTERNATE PATHS will generate m lines of status, each defining the
instantaneous AVAILABILITY of one of the m ALTERNATE PATHS.  A
logical "O" on any status line means the associated alternate path is
ava...