Browse Prior Art Database

Transmission Group Termination in System Network Architecture

IP.com Disclosure Number: IPCOM000048480D
Original Publication Date: 1982-Feb-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 3 page(s) / 70K

Publishing Venue

IBM

Related People

George, FD: AUTHOR [+2]

Abstract

A procedure is described herein which enables a System Network Architec ture (SNA) node to determine when a transmission group (TG) is not being used. This information may be used for timely termination of switched connections.

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Transmission Group Termination in System Network Architecture

A procedure is described herein which enables a System Network Architec ture (SNA) node to determine when a transmission group (TG) is not being used. This information may be used for timely termination of switched connections.

For a detected description of a particular SNA configuration to which this modification has application, see reference (*). Between every pair of subarea nodes, up to eight loop-free explicit routes (ERs) are defined. Thus, a node B will have up to eight ERs defined to every destination subarea node (DSA) A, where these routes are denoted by the pair A.ERN, where ERN is the "explicit route number" between 0 and 7. The routes are reversible in the sense that given the route A.i defined from node B to node A, there must be a route B.j defined from node A to node B which travels along the reverse sequence of transmission groups (TGs). Furthermore, the routing tables used in the nodes are source independent in that the outbound TG for a message arriving at an intermediate node C is determined by its destination subarea and ERN, irrespective of its source.

If no active sessions are using a particular TG, then the links of the TG may be brought down, saving the network owner telephone charges. A mechanism is described to determine whether a TG is in use by keeping track of the ERs in use.

To accomplish this, it is assumed that when node B wants to use ER number i to node A, it sends an ER ACT (A.i) message on A.i and each node on the way processes this message. ER ACT REPLY (B.j) is sent by node A to node B, where B.j is the reverse of A.i. At termination, node B sends ER--DEACT (A.i) and node A replies with ER DEACT REPLY (B.j).

The proposed TG use tracking technique is as follows. A DSA.ERN. ITG flag is a single bit with the following interpretation. If DSA.ERN.ITG=1 at an intermediate node C, then route DSA.ERN is active through node C, and furthermore it is active over the incoming TG (ITG). Otherwise, DSA.ERN is not active over ITG. Route DSA.ERN is not active through node C if DSA.ERN.IT equals 0 for every incoming TG, and...