Browse Prior Art Database

Message Protocol

IP.com Disclosure Number: IPCOM000077380D
Original Publication Date: 1972-Jul-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 14K

Publishing Venue

IBM

Related People

Seroussi, SF: AUTHOR [+2]

Abstract

There is disclosed herein a message protocol which is advantageously employed in a computer network (a network of heterogeneous computing entities or nodes). A typical arrangement of such a network is one wherein there is a plurality of interconnected user nodes.

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

Page 1 of 2

Message Protocol

There is disclosed herein a message protocol which is advantageously employed in a computer network (a network of heterogeneous computing entities or nodes). A typical arrangement of such a network is one wherein there is a plurality of interconnected user nodes.

In such type of network, messages can be of any desired length, there merely being required that long messages be transmitted in several blocks. The nodes will route the message blocks to their proper destinations. However, it is clear that these nodes are unaware of actual message boundaries. In the transmission, each block includes a header and a text. The network communication system does not assemble several short messages into one block for transmission between user nodes. However, message processing routines in a user node may accomplish such assembling when more than one message has the same destination. Thus, it is the responsibility of the matching user program at a receiving node to recover the several messages which originally were processed by the network as a single message.

In accordance with the message protocol described herein, blocks, which are transmitted from one node to another are sequentially numbered, the sequence number being a part of a block header. A discrete transmitted-block sequence number is maintained for every node to which a communication channel is open. In addition, a separate received-block sequence number is maintained, which represents the expected number of the next block to be received from each open communication channel.

The rationale for applying the sequence numbers is the desire to transmit blocks in a conversational manner. For example, when a block is transmitted from nods A to B, node B is enabled to reply with an acknowledgement of the receipt of the block and to transmit another block to node A. The effect of such arrangement is to reduce the number of line reversals from two per block to one per block, when both of the nodes have messages to transmit. An additional advantage which results from the arrangement is the capability of sending messages in one direction even though messages may be queued for transmission in the opposite direction.

In the operation of the protocol, a prepare command chained to a read command is present in both of the sending and receiving nodes telecommunication terminals when an idle condition exists, thereby signifying that neither node has a message to transmit or is waiting for an acknowledgement. Considering the previously set forth example, when node A wishes to send a block to node B, node A transmits a physical positive acknowledgment and the appropriate sequence number, followed by the message block, i.e., a header containing the transmitte...