Browse Prior Art Database

Systems Network Architecture over Tranmission Control Protocol with Multiprotocol Transport Networking as a Data Link Control

IP.com Disclosure Number: IPCOM000114684D
Original Publication Date: 1995-Jan-01
Included in the Prior Art Database: 2005-Mar-29
Document File: 6 page(s) / 126K

Publishing Venue

IBM

Related People

Morris, RP: AUTHOR

Abstract

Disclosed is a method that enables a Systems Network Architecture protocol stack to be broken below its Path Control layer and run over a non-SNA transport network using Multiprotocol Transport Networking (MPTN) architecture.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 42% of the total text.

Systems Network Architecture over Tranmission Control Protocol with
Multiprotocol Transport Networking as a Data Link Control

      Disclosed is a method that enables a Systems Network
Architecture protocol stack to be broken below its Path Control layer
and run over a non-SNA transport network using Multiprotocol
Transport Networking (MPTN) architecture.

      MPTN architecture is an IBM* architecture accepted by X/Open
that supports mixed protocol networking.  That is, MPTN enables
application programs designed to operate over one transport protocol
(e.g., SNA, NetBIOS, OSI, or TCP/IP) to operate over additional
transport networks.

      The MPTN architecture specifies that a SNA stack should
interface with an MPTN as if the MPTN is a SNA Path Control layer
(1).  A component, known as the SNA syntax mapper provides this
interface.  That is, the syntax mapper appears to be a Path Control
componene to the SNA stack.  This paper discloses software that
enables the SNA stack to interface to an MPTN one layer lower.  That
is, the syntax mapper appears to be a Data Link Control (DLC)
component to the SNA stack.

      SNA frames passed to a SNA Path Control component are whole
Basic Information Units (BIU) (2).  SNA frames passed from a SNA Path
Control component to a DLC component are Path control Information
Units (PIU).  PIUs may contain partial or segmented BIUs.  This
segmentation requires that the SNA syntax mapper perform the
following
functions differently than specified in the MPTN architecture.
  o  Sending SNA frames to the MPTN
  o  Receiving SNA frames from MPTN
  o  SNA pacing
  o  Buffer management

A summary list of the new capabilities required for the SNA syntax
mapper follows:
  1.  The syntax mapper must be able to distinguish between frames
that
       contain a first segment , a middle segment, and/or an end
segment
       of a BIU.
  2.  Send and receive pacing must be done on the basis of complete
       BIUs exchanged between the syntax mapper and MPTN, not frames
       passed between the syntax mapper and MPTN.
  3.  In managing send and receive buffers, the syntax mapper must be
       able to detect whether a buffer is for a whole, first, middle,
or
       end of a BIU.
  For pseudocode for a syntax mapper appearing as a Path Control
layer, see (1).  The pseudocode for a syntax mapper appearing as a
DLC follows.

Send Processing
  int send( ...)
  {
    If its the first segment of a BIU and its an IPM then
    {
      If its an unsolicited IPM
      {
        reset the current receive pacing window
        send a reset acknowledgement to SNA
        return
      }
      If there's no RU then
      {
        set the receive_pacing_window as if fixed pacing is in use
      }
      else
        set the receive_pacing_window as if adaptive pacing in use
      If fl...