Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Dual Check Field Generation

IP.com Disclosure Number: IPCOM000046894D
Original Publication Date: 1983-Aug-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 3 page(s) / 52K

Publishing Venue

IBM

Related People

Boudreau, PE: AUTHOR

Abstract

In some communication networks it is desirable to separate the physical access and interconnect addressing from the link control protocols and information. It is essential that the addresses (typically, To and From) are not unknowingly altered as a result of transmission errors. It is of utmost importance that the communication adapter of the receiving station have assurance that the frame or message was meant for it since the adapter will pass the protocol and information fields unaltered to the connected station. This article describes an economical yet accurate technique for detecting erroneous physical access and physical addressing totally separate from the link protocol and information content of a frame or message.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 55% of the total text.

Page 1 of 3

Dual Check Field Generation

In some communication networks it is desirable to separate the physical access and interconnect addressing from the link control protocols and information. It is essential that the addresses (typically, To and From) are not unknowingly altered as a result of transmission errors. It is of utmost importance that the communication adapter of the receiving station have assurance that the frame or message was meant for it since the adapter will pass the protocol and information fields unaltered to the connected station. This article describes an economical yet accurate technique for detecting erroneous physical access and physical addressing totally separate from the link protocol and information content of a frame or message. This is accomplished by using the same cyclic checking technique and apparatus for protecting the two distinct portions of the frame separately. A conventional frame format where a single check field is employed has the following format: DbP At Af [C, (Info)] F De

where

Db = Begin or start delimiter

P = Physical access

At = "TO" address

Af = "FROM" address

C = Link Protocol (Info) = Information F = Cyclic check field

De = End delimiter Where the message or frame is divided into two fields each having its own check field, the following format may be used: Db P At Af F* [C, (Info)] F De where

F* = Cyclic check field covering part of P through F*

F = Cyclic check field covering part of P through F

including F* The circuit diagram of Fig. 1 is a typical circuit for generating a conventional frame check sequence based on premultiplication by Xk, division by the generator polynomial (of degree k), g(x) = 1+g1x1 + g2x2 + ... + gk-1xk-1 + xk and inverting the calculated k redundancy bits to yield a non-zero coset. The circuit diagram illustrated...