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Browse Prior Art Database

Discard Indicators

IP.com Disclosure Number: IPCOM000100342D
Original Publication Date: 1990-Apr-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 1 page(s) / 32K

Publishing Venue

IBM

Related People

Irwin, JW: AUTHOR

Abstract

An I/O channel feature is described wherein a simple serial channel contains a single level of buffering for receiving incoming frames and a set of three or more discard indicators to identify the type of frame that was discarded in the event of an overrun.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

Discard Indicators

       An I/O channel feature is described wherein a simple
serial channel contains a single level of buffering for receiving
incoming frames and a set of three or more discard indicators to
identify the type of frame that was discarded in the event of an
overrun.

      Overruns are prevented by protocol during ordinary link traffic
conditions; however, in the event of certain errors, frames may be
received faster than they can be processed.  When a crosspoint switch
is installed in the network, the type of frame discarded is
important.  This information is used for accurate error logging and
fault location.  The information is also used for determining the
connection state of the crosspoint switch so that proper disconnects
may be issued to clear the network.

      Prior channels have set a single overrun indicator to indicate
loss of an incoming frame.  The improvement described here includes
the following features:
 1.  Dynamic sensing of the frame type of the discarded frame as it
is received.  This is accomplished by comparing specific bytes of the
incoming frame against templates as it passes through the receive
pipeline.  At a minimum, frames are categorized as busy frames,
reject frames, and other frames.  Additional categories may be
specified if needed.
 2.  Three (or more) overrun indicators, each indicator set when a
specific type of incoming frame has been discarded.