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Connectionless ATM Network Support using Virtual Path Connections

IP.com Disclosure Number: IPCOM000109415D
Original Publication Date: 1992-Aug-01
Included in the Prior Art Database: 2005-Mar-24
Document File: 4 page(s) / 186K

Publishing Venue

IBM

Related People

Le Boudec, J: AUTHOR [+3]

Abstract

Disclosed is a method for supporting direct connectionless ATM by means of virtual path connections. The direct connectionless ATM service is described in (1). It requires either a global multiplex identification (MID) distribution, or MID swapping between switching nodes. The use of virtual path connections between nodes provides a simple procedure by which the sending parties can choose their own MID independent of each other.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Connectionless ATM Network Support using Virtual Path Connections

       Disclosed is a method for supporting direct
connectionless ATM by means of virtual path connections.  The direct
connectionless ATM service is described in (1).  It requires either a
global multiplex identification (MID) distribution, or MID swapping
between switching nodes.  The use of virtual path connections between
nodes provides a simple procedure by which the sending parties can
choose their own MID independent of each other.

      The connectionless service described here is offered to the
members of a given "domain".  A domain is composed of switches and
Connectionless Service Users (CLSUs).  In a domain, every switch is
allocated a Switch Identification (SI); it is 8 bits long.  Every
CLSU is allocated an identification called User Identification (UI);
it is 8 bits long.  The UI is local to a given switch.  The complete
domain address (D@) of a CLSU is the concatenation of the UI and the
SI; it is 16 bits long.

      The ATM connectionless cells at the interface between switch
and CLSU are marked in the header as "connectionless".  This is
performed by setting the first 8 bits in the VPI/VCI field to "1".

      Every switch has at least one Virtual Path Connection (VPC) to
every other switch in the domain.  The interface between switches is
assumed to be the CCITT User-Network Interface, thus virtual path
switching is based on a 1-byte long field (the VPI).  The VPCs are
terminated in the switches in Virtual Path Terminators (VPTs).  A VPT
accepts cell payloads for transmission on a VPC identified by a port
and a VPI.  In addition to the cell payload, the VPT accepts as
argument the VCI to be transmitted to the end of the VPC (Fig. 1).
This VCI is 16 bits long.

      The switches maintain destination tables that map the
destination SIs to the VPI and port names.  The port names are
internal to the switches.  Conversely, the switches also maintain
source tables that map the port names and VPIs to origin SIs (Fig.
2).

      The connections are established and maintained using the normal
procedures, as described in (2).  These VPCs cannot be shared with
other types of traffic than the connectionless cells described here.

      The switches are assumed to have the ATM connectionless
capability, i.e., they can forward cells to output ports based on the
D@ contained in the cell header.  This is performed as in (1).

      In addition, the switch should be able to convene the identity
of the input port to the output port.  The ATM connectionless
operation of the switch is thus as follows: assume a cell with
VPI/VCI field equal to "'1...1' s1 a2" is submitted on the input
identified by the UI value a1, then the cell is forwarded to the
output with label a2, with the VPI/VCI field equal to "'...