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Browse Prior Art Database

Timeout Mechanism for the Reuse of Interconnect Sequence Numbers

IP.com Disclosure Number: IPCOM000113112D
Original Publication Date: 1994-Jul-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Baldus, DF: AUTHOR [+2]

Abstract

Disclosed is a timeout mechanism which allows the reuse of sequence numbers when the preferred indication of reusability has been lost.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 56% of the total text.

Timeout Mechanism for the Reuse of Interconnect Sequence Numbers

      Disclosed is a timeout mechanism which allows the reuse of
sequence numbers when the preferred indication of reusability has
been lost.

      High-performance interconnect architectures use an asynchronous
paradigm; transactions are transmitted via packets on unidirectional
links.  The packet sender has no immediate knowledge of whether a
packet was accepted correctly or corrupted and lost.  Protocols
(e.g., SCI) specify acknowledgement (echo) packets which are
transmitted back to the sender indicating packet acceptance.  Once
this indication is received, a sender knows that the packet need not
be retransmitted and can deallocate the packet buffer; allowing a new
packet to be transmitted.  High performance, highly parallel systems
may require that a Unit allow multiple outstanding transactions at
any given time.  "Sequence numbers" (also called "sequence IDs,"
"transactions IDs," "tags," etc.) are placed into packets and their
subsequent echoes so packet senders may "pair-up" packets and echoes
(and thus know which of the outstanding packets has been accepted).
This invention consists of the following components and assumptions:

o   N sequence numbers.

o   An N-bit register SEQ_ID.  A "1" in bit position j of the
    register indicates that sequence number j is "in use."  A "0" in
    bit position j indicates that sequence number j is available for
    use.

o   When a trans...