Browse Prior Art Database

Port Manager - Short Hold Mode

IP.com Disclosure Number: IPCOM000035727D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Li, L: AUTHOR [+3]

Abstract

This article describes a method of operation on switched connections which allows the implementation of short hold mode (SHM) to be performed in a processor with minimal impact to data link control (DLC) operation.

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Port Manager - Short Hold Mode

This article describes a method of operation on switched connections which allows the implementation of short hold mode (SHM) to be performed in a processor with minimal impact to data link control (DLC) operation.

In SHM the physical connection between two communicating parties is temporarily disconnected when an idle period is detected, and reconnected when either side wishes to resume communication. The users of this physical connection are not aware of the temporary disconnections and will maintain an active logical connection throughout the time.

Typically, SHM has been a function imbedded into the DLC layer. The result has been that a function which is very well defined such as DLC was made to support a new and complicated function, something it was not designed to support. The results have been a workable but nonelegant implementation of SHM.

In the method disclosed herein the port manager concept is used to separate the support of SHM from the DLC. In SHM a data communications link between two computers or intelligent systems is over a switched (telephone/data) network. Conventionally, the implementation of SHM has been on CCITT X.21 data networks. Fig. 1 shows the port manager SHM support in block diagram. The port manager has built-in logic to establish the switched connection. In other words, the port manager supports CCITT X.21 and CCITT V.25 interface procedures. The DLC layer is able to detect information transfers on the communication link that was set up for it...