Browse Prior Art Database

Elimination of Message Congestion in a Computer Network

IP.com Disclosure Number: IPCOM000078020D
Original Publication Date: 1972-Oct-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 4 page(s) / 26K

Publishing Venue

IBM

Related People

Karp, DP: AUTHOR [+2]

Abstract

In the development of computer networks (networks of heterogeneous computing entities), there is encountered the problem of lockups. Several types of lockups (reassembly, direct and indirect store and forward) can occur in a distributed network. There is described herein an arrangement for resolving these lockups. Such resolution is effected within the framework of a flexible protocol, which enables interactive communications between the computing entities. There is first described herein the basic element of such line protocol, i.e., a message header. This message header is the carrier of information through the network and as such is the foundation upon which the network transactions are effected.

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Elimination of Message Congestion in a Computer Network

In the development of computer networks (networks of heterogeneous computing entities), there is encountered the problem of lockups. Several types of lockups (reassembly, direct and indirect store and forward) can occur in a distributed network.

There is described herein an arrangement for resolving these lockups. Such resolution is effected within the framework of a flexible protocol, which enables interactive communications between the computing entities. There is first described herein the basic element of such line protocol, i.e., a message header. This message header is the carrier of information through the network and as such is the foundation upon which the network transactions are effected.

The header comprises a plurality of well-defined fields, each of these fields providing an essential link within the protocol. In the figure, there is shown an embodiment of a message header according to this disclosure. The header in the example shown suitably has a ninety-six bit width. The various fields therein are legended with individual mnemonics. The full names of the fields and their functions are set forth hereinbelow. Action Code 1 (AC1).

The function of this code is to indicate the line control options available between two computing entities or nodes within the network. It denotes that a node has performed a specific action on the line and that a response may or may not be required, depending upon the function specified in the received message. This field is interpreted and modified by the communications interface, and together with the next adjacent field, TBN 1 (TRANSMISSION BLOCK NUMBER
1) constitute the line control message. An error in this field elicits an appropriate response from the interface.

In the situation of a communication with an adjacent node, the field can also indicate an end-to-end reply. In other words, it also functions as a logical control. Transmission Block Number 1 (TBN 1).

The transmission block number is a field which is maintained by receiving stations to indicate, as part of a reply, the sequence number of the last message which is received. The main function of this field is to provide a check on the exchange of transmissions between adjacent nodes, in order to avoid the loss of messages. An error in this field causes the proper control message to be sent by the recipient thereof. Transmission Block Number 2 (TEN 2).

This field is maintained and updated by the interface. It is employed as a sequence number and inserted into all outgoing messages which function, together with field TBN 1, to check for proper message order. As a message passes through the various nodes in the network to its final destination, both fields TBN 1 and TBN 2 are overlaid by the corresponding values in each node. Action Code 2 (AC 2).

This code indicates a logical function which is being exchanged. Its operation is to determine whether a request is being made or...