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Browse Prior Art Database

Collision of Connect Frames in Cascaded Optical Switch

IP.com Disclosure Number: IPCOM000120148D
Original Publication Date: 1991-Mar-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Kaiser, JM: AUTHOR [+3]

Abstract

Disclosed is a method of resolving frame collision problems in the cascaded fiber-optic switch, allowing one connection to be maintained.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 85% of the total text.

Collision of Connect Frames in Cascaded Optical Switch

      Disclosed is a method of resolving frame collision
problems in the cascaded fiber-optic switch, allowing one connection
to be maintained.

      The RISC System/6000* (RS/6000) switch architecture allows
cascading the switches.  This is done by defining one switch to be
high and the other to be low priority.  The collision occurs when
both switches are in a certain state (MONO-D) and each receives a
connect frame from the other switch.  The basic idea is to allow the
frame received at the high priority port to be transferred and
discard the connect frame received at the other port.  This is an
attempt to preserve at least one connection since the switch
connected ports are in high demand.  These assigned ports are the
gateway for connection of one switch to another.

      As shown in the figure, port-2 in switch (Sw) 1 and port-3 in
switch 2 are assigned as high and low priority, respectively.  The
connect frame received at port-4 is discarded, and the connect frame
received at port-1 will be transmitted to switch 2 and, in turn, to
link-4.  The frame received at port-3 from port-2 will cause an
interrupt to the processor. The processor directs hardware to
transmit a BUSY frame.  The hardware issues a BUSY frame to link-4
and disconnects port-4 and port-3, since the connection between these
two ports had been established.  A new connection will be established
between port-3 and port-4 based o...