Browse Prior Art Database

Prevention of Redundant Frame Transmission in Closed Ring Networks

IP.com Disclosure Number: IPCOM000045429D
Original Publication Date: 1983-Mar-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 14K

Publishing Venue

IBM

Related People

Weiss, L: AUTHOR

Abstract

In certain contemporary ring networks data processing stations communicate as peers by transmitting information in structured variable-length frames containing header and terminal control portions of predetermined length. In such systems, each "informational" frame sent from an "origin station" to a specific "destination" station (such frames containing data or control information) must be specifically acknowledged by a response frame sent from the same destination station to the origin station. The origin station will not send another informational frame to the same destination until it receives an acknowledgment indicating correct reception of the previous frame.

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Prevention of Redundant Frame Transmission in Closed Ring Networks

In certain contemporary ring networks data processing stations communicate as peers by transmitting information in structured variable-length frames containing header and terminal control portions of predetermined length. In such systems, each "informational" frame sent from an "origin station" to a specific "destination" station (such frames containing data or control information) must be specifically acknowledged by a response frame sent from the same destination station to the origin station. The origin station will not send another informational frame to the same destination until it receives an acknowledgment indicating correct reception of the previous frame.

If an informational frame is not acknowledged (by a response frame) within a predetermined interval of time, the transmitting station, under control of its processing software, will originate a retransmission of that frame. If such retransmissions are performed and the original frame transmission had been properly received but the response frame was lost, the retransmitted information will be passed to the software of the receiving station causing unnecessary processing activity at the receiving station to account for the redundancy of that information. A method of avoiding such unnecessary activity is disclosed below.

The ring interfacing hardware at each station includes a microprocessor having storage facilities separate from those of the host processor which ultimately processes the data. The microprocessor or storage is generally sufficient to hold considerable control information relative to every other station on the ring.

In the present instance one item of such control information could be an odd/even bit, and another could be power-on status. A common set of bits is used for receiving, and a different set is used for transmitting. A third bit is dedicated to indicating that the last frame received had the power-on status bit active in the specifier byte.

Each informational and response frame contains a type-specifier byte distinguishing Informational frames from response frames, data information from control information, positive responses from negative responses, etc. Data information, control information and positive response specifier bytes also contain a bit dedicated to indicating power-on status and another bit dedicated...