Browse Prior Art Database

Hardware-Assisted Trace Filtering

IP.com Disclosure Number: IPCOM000112191D
Original Publication Date: 1994-Apr-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Byrn, JW: AUTHOR [+3]

Abstract

A method for general purpose protocol frame matching is disclosed. A general purpose hardware filter is used to interrogate protocol frames as they are received. The filter and receive logic are done in parallel.

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

Hardware-Assisted Trace Filtering

      A method for general purpose protocol frame matching is
disclosed.  A general purpose hardware filter is used to interrogate
protocol frames as they are received.  The filter and receive logic
are done in parallel.

      The hardware filter interrogates each frame byte-by-byte as it
is received off of the network.  This is done by placing a
microcodable filter within the network adapter chip.  The filter's
instructions allow the user to setup a filter with arbitrary matching
logic.  For example, the user could setup a filter to trace all SNA
traffic that originates from/to this device.  As frames are
interrogated by the hardware they are either discarded because they
do not match the filter, or they are passed on to the trace
application for further processing.  Each filter instruction allows
the user to do arbitrary things with each byte of the data stream.
For example, match data, mask data, skip, load a skip count, save
state, etc.  The only limitation on how complex the filter can be is
determined by how many filter instructions are available to use and
the filter operations provided.

      The Figure shows how the filter logic conceptually works on
each incoming frame to produce a match/no match condition.