Browse Prior Art Database

Short Frame Error Counter With Idle Flags

IP.com Disclosure Number: IPCOM000100435D
Original Publication Date: 1990-Apr-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 1 page(s) / 45K

Publishing Venue

IBM

Related People

Bederman, S: AUTHOR

Abstract

The High-Level Data Link Control (HDLC) protocol is a Layer 2 protocol that envelops a frame between a pair of delimiter octets that are called "Delimiter Flags". These Flag octets use the bit pattern '01111110'. A number of related Layer 2 protocols, including Synchronous Data Link Control for D-Channel (LAPD), also employ a similar set of Delimiter Flags for the Layer 2 frames.

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Short Frame Error Counter With Idle Flags

       The High-Level Data Link Control (HDLC) protocol is a
Layer 2 protocol that envelops a frame between a pair of delimiter
octets that are called "Delimiter Flags".  These Flag octets use the
bit pattern '01111110'.  A number of related Layer 2 protocols,
including Synchronous Data Link Control for D-Channel (LAPD), also
employ a similar set of Delimiter Flags for the Layer 2 frames.

      Some of the above protocols can be used for both point-to-point
configurations of end stations (only 2 end stations are connected by
a physical channel) and for point-to-multipoint configurations of end
stations (wherein a "master" station communicates with multiple
"slave" stations that share the same physical channel).  The LAPB
protocol may only be used for a point-to-point configuration.

      Where any of the above protocols (HDLC, SDLC, LAPD, etc.) are
used in conjunction with a point-to-point configuration, then the
interval between the transmission of successive frames on the
physical channel can be used to transmit an integer number of Flag
octets.  These are herein termed "Idle Flags".

      The Layer 2 "protocol data units" that are transmitted within a
frame of the above Layer 2 protocols have an associated minimum
number of non-Flag octets that must be enclosed within a pair of
Delimiter Flags in order for the frame to satisfy the requirements
for validity.  For example, the minimum size of an ISDN LAPD p...