Browse Prior Art Database

High-Speed Network Adapter Error Trace Mechanism

IP.com Disclosure Number: IPCOM000121005D
Original Publication Date: 1991-Jul-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 68K

Publishing Venue

IBM

Related People

Eijan, UG: AUTHOR [+4]

Abstract

This article describes a method and hardware enablement for finding causes of data link framing errors when data is received over a high- speed link.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 57% of the total text.

High-Speed Network Adapter Error Trace Mechanism

      This article describes a method and hardware enablement
for finding causes of data link framing errors when data is received
over a high- speed link.

      The trace facility disclosed herein runs on a T1 communications
adapter.  The T1 adapter consists of two digital signal processors
(DSPs) using common memory and protocol assist logic.  DSP1 performs
a transmit function while DSP2 performs the receive function.  The T1
line consists of a number of synchronous data link control
(SDLC)-type channels.

      The T1 bytes are processed by protocol assist logic and
microcode which extracts data link frames from the T1 data stream.
Also, inserted zero bits are removed and cyclic redundancy check
(CRC) is checked.  Then the actual data received is placed in a
receive host buffer.  In addition, the data link frames use an
SDLC-type protocol which is a bit-oriented protocol.  Therefore, the
bytes may not be aligned to byte boundaries.  Protocol assist logic
aligns the bytes.

      Many communication adapter card failures (bugs) can be caused
by a certain data pattern being received on the T1 line.  The form of
the input data is not apparent from the host data buffer bytes.  The
additional history queue of T1 bytes would show this format.

      Referring to the drawing, the T1 bytes are received by the
receive microcode.  Using the protocol assist hardware they are then
input to the host buffer...