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Servicing Terminals on Multipoint Lines With a Communications Controller

IP.com Disclosure Number: IPCOM000075024D
Original Publication Date: 1971-Jul-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 14K

Publishing Venue

IBM

Related People

Rommelfanger, AC: AUTHOR [+2]

Abstract

This description is directed to a technique for servicing terminals on a multipoint line. The technique expands the traditional polling technique so that both polling and addressing are included. By making such a change, the conflicts and priority problems between sending and receiving are eliminated. The user is able to define the priority of one terminal on a multipoint line with respect to the other terminals on that line, and with respect to the total work load that is to be performed on that line. At any point in time, the lines' operation will adjust to fit the current work load. Furthermore, the technique provides a method of interleaving multiple sessions, i.e.

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Servicing Terminals on Multipoint Lines With a Communications Controller

This description is directed to a technique for servicing terminals on a multipoint line. The technique expands the traditional polling technique so that both polling and addressing are included. By making such a change, the conflicts and priority problems between sending and receiving are eliminated. The user is able to define the priority of one terminal on a multipoint line with respect to the other terminals on that line, and with respect to the total work load that is to be performed on that line. At any point in time, the lines' operation will adjust to fit the current work load. Furthermore, the technique provides a method of interleaving multiple sessions, i.e. a sequence of command and data interchanges between a CPU and a terminal, with multiple terminals - buffered or nonbuffered - on all multipoint lines in accordance with user specified parameters and under user control. This is accomplished by breaking a session into a series of logical connections. The logical connection is the period during which one terminal has use of the line and the session between it and the host is serviced. Parameters Governing Logical Connection.

To allow for the differing requirements of individual systems, the communications controller (CC) provides a number of parameters which restrict a terminal's ability to monopolize the multipoint line to which it is connected.
1) Session Limit - The user can specify for the multipoint line

the number of sessions that he would like to concurrently

allow on this line. This number will depend upon the types of

applications

for which the terminals on the line are used, as well as

the type of terminal on the line. The CC will attempt to

maintain this number of sessions on the line whenever possible
2) Transmission Limit - For each terminal on the multipoint line

the user specifies, the maximum number of transmissions which

can be sent to and received from a terminal during any logical

connection. When this maximum is reached, the logical

connection will

be broken and the session will be continued at a later time.
3) Read Termination Action - The user can specify if a logical

connection should be broken when a terminal does not respond

to a Read command.

The following paragraphs set out a technique for establishing a session with terminals on a multipoint line. This technique expands the traditional polling technique so that it handles both the Invite and Contact commands for establishing a session.

When the number of sessions on a multip...