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Ethernet IOP/ Tranceiver SQE Compatibility Algorithm

IP.com Disclosure Number: IPCOM000121990D
Original Publication Date: 1991-Oct-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 3 page(s) / 93K

Publishing Venue

IBM

Related People

Aho, ME: AUTHOR [+3]

Abstract

In an attempt to create a CSMA/CD (carrier sense multiple access with collision detection) adapter interface that is both flexible enough to fit in all environments and provides the best signal quality reporting possible, an adaptable interface algorithm has been designed. This algorithm allows the Ethernet adapter to take advantage of the Signal Quality Error (SQE) feature on many transceivers while not requiring that feature to be present to function properly.

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

Ethernet IOP/ Tranceiver SQE Compatibility Algorithm

      In an attempt to create a CSMA/CD (carrier sense multiple
access with collision detection) adapter interface that is both
flexible enough to fit in all environments and provides the best
signal quality reporting possible, an adaptable interface algorithm
has been designed.  This algorithm allows the Ethernet adapter to
take advantage of the Signal Quality Error (SQE) feature on many
transceivers while not requiring that feature to be present to
function properly.

      The lowest level of SQE signalling has the ability at data
transmission time to detect a broken line connection or a
malfunctioning transceiver.  Three conditions are reported by the SQE
signal:
     -  Improper signals on the medium
     -  Collision on the medium
     -  Reception of an output idle message.

      If SQE signalling is not used, data is simply pushed out the
line and no indication of a connection is returned. Note that
adapters that require the use of SQE signalling cannot be used in
environments where SQE is not present (i.e., with transceivers that
do not provide the SQE signal).  Adapters that ignore the SQE signal
sacrifice a level of signal detection that may be important to the
user.

      IBM mainframes and the AS/400* system currently require the use
of the SQE signalling feature.  When using these systems, if a
transceiver does not produce the SQE signal, an error will be
reported and no data transmission will occur.  IBM workstations and
PCs ignore SQE signalling as do most other vendors of Ethernet
adapters.

      The following section describes the unique algorithm developed
to provide increased flexibility in the Ethernet environment.  To the
author's knowledge, no other products implement this algorithm.  By
implementing the steps below, an adapter can take advantage of the
SQE feature on an "as can" basis and still operate in a non-SQE
environment.
     1.  Activate adapter and check for SQE signal.
     2.  If the SQE...