ISO/IEC 4335:1993/Amd 7:1995
(Amendment)Information technology —- Telecommunications and information exchange between systems — High-level data link control (HDLC) procedures — Elements of procedures — Amendment 7: Enhanced multi-selective reject option
Information technology —- Telecommunications and information exchange between systems — High-level data link control (HDLC) procedures — Elements of procedures — Amendment 7: Enhanced multi-selective reject option
Extends the multi-selective reject option by including a streamlined and detailed set of procedures that do not generate duplicate retransmissions and allow the maximum number of outstanding frames to be less than or equal to modulus number minus one.
Technologies de l'information — Télécommunications et échange d'informations entre systèmes — Procédures de commande de liaison de données à haut niveau (HDLC) — Éléments de procédures — Amendement 7: Option de rejet à choix multiples améliorée
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Standards Content (Sample)
INTERNATIONAL lSO/IEC
STANDARD 4335
Fifth edition
1993-12-15
AMENQMENT 7
1995-11-15
-
Information technology - Telecommunications
and information exchange between Systems -
High-level data link control (HDLC) procedures -
Elements of procedures
AMENDMENT 7: Enhanced multi-selective reject
Option
Technologies de I ’information - T~ltkommunications et kchange d ’information
entre syst&mes - Procedures de commande de liaison de donnbes 2 haut niveau
(HDLC) - &ments de procbdures
AMENDEMENT 7: Option de rejet 2 choix multiples ameliorke
Reference number
ISO/IEC 4335:1993/Amd.7:1995(E)
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ISO/IEC 4335:1993/Amd.7:1995(E)
Foreword
ISO (the International Organization for Standardization) and IEC (the Inter-
national Electrotechnical Commission) form the specialized System for
worldwide standardization. National bodies that are members of ISO or
IEC participate in the development of International Standards through
technical committees established by the respective organization to deal
with particular fields of technical activity. ISO and IEC technical
committees collaborate in fields of mutual interest. Other international
organizations, governmental and non-governmental, in liaison with ISO and
IEC, also take part in the work.
In the field of information technology, ISO and IEC have established a joint
technical committee, lSO/lEC JTC 1. Draft International Standards adopted
by the joint technical committee are circulated to national bodies for
voting. Publication as an International Standard requires approval by at
least 75 % of the national bodies casting a vote.
Amendment 7 to International Standard lSO/IEC 43351993 was prepared
by Joint Technical Committee lSO/IEC JTC 1, Information technology,
Subcommittee SC 6, Telecommunications and informaGon exchange
between Systems.
0 ISO/IEC 1995
All rights reserved. Unless otherwise specified, no part of this publication may be
reproduced or utilized in any form or by any means, electronie or mechanical, including
photocopying and microfilm, without Permission in writing from the publisher.
lSO/IEC Copyright Office l Case postale 56 l CH-l 211 Geneve 20 l Switzerland
Printed in Switzerland
ii
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0 ISOAEC ISOIIEC 4335:1993/Amd.7:1995(E)
Introduction
This amendment to ISOAEC 4335:1993 further extends the multi-selective reject Option
by including a streamlined and detailed set of procedures that do not generate
duplicate retransmissions and allow the maximum number of outstanding frames to be
less than or equal to modulus number minus one.
. . .
Ill
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0 ISO/IEC ISOIIEC 4335:1993/Amd.7:1995(E)
Information technology - Telecommunications and information exchange
between Systems - High-level data ink control (HDLC) procedures - E lements
of procedures
AMENDMENT 7: Enhanced multi-selec ive reject Option
Page 19
Subclause 8.2.1
After first Paragraph, add a new Paragraph as follows:
When using the multi-selective reject Option, any I frames that were retransmitted
subsequent to the transmission of the last frame with the P/F bit, respectively, set to
“1 ”) shall not be retransmitted. For a combined Station, if any frames are retransmitted,
then a poll shall be sent, either by transmitting an Rf? command (or RNR command if
the Station is in the busy condition) with the P bit set to “1” or by setting the P bit to “1”
in the last retransmitted I frame.
In the Paragraph labelled c), modify the first 2 lines as follows:
In the case of a secondary/primary Station, if the multi-selective reject Option is not used
and if one or more SREJ frames . . . . .
In the Paragraph labekd d), modify the first 2 lines as follows:
In the case of a combined Station, if the multi-selective reject Option is not used and if a
SREJ command with . . . . .
Add new Paragraph labeled i):
i) In the case of a primarykecondary Station, when the multi-selective reject Option is
used, Checkpoint retransmission on receipt of an RR frame with the P/F bit set to “1”
shall be inhibited if any new I frames were transmitted subsequent to the last frame with
the P/F bit set to “1 ”. In the case of a combined Station, when the multi-selective reject
Option is used, Checkpoint retransmission on receipt of an RR frame with the F bit set to
“1” shall be inhibited if any new I frames were transmitted subsequent to the last frame
with the P bit set to "1".
Page 79
Subclause 8.2.3
Replace text as follows:
The SREJ command/response shall be used primarily to initiate more efficient error
recovery by requesting the retransmission of one or more (not necessarily contiguous) I
frames following the detection of sequence errors rather than the retransmission of the
earliest frame in need of retransmission plus all additional I frames which may have
been transmitted subsequently.
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ISO/lEC 4335:1993/Amd.7:1995(E) @ISO/IEC
8.2.3.1 Single SREJ recovery
The SREJ command/response shall be used primarily to initiate more efficient error
recovery by requesting the retransmission of a Single I frame following the detection of
a sequence error rather than the retransmission of the I frame requested plus all
additional I frames which may have been transmitted subsequently.
When an I frame sequence error is detected, and it is determined that SREJ recovery is
to be employed, the SREJ frame shall be transmitted at the earliest possible time.
When a primary/secondary Station sends one or more SREJ frames, each with the P/F
bit set to “0 ”, and these “sent SREJ” exception conditions are not cleared when the
primary/secondary Station is ready to issue the next frame with the P/F bit set to “l”, the
primary/secondary Station shall send an SREJ frame with the P/F bit set to “1” with the
same N(R) as the oldest unresolved SREJ frame. When a combined Station sends one
or more SREJ commands, each with the P bit set to ‘0” or “1 ”, or one or more SREJ
responses, each with the F bit set to “0” and these “sent SREJ” exception conditions
are not cleared when the combined Station is ready to issue the next response frame
with the F bit set to “l”, the combined Station shall send an SREJ response with the F
bit set to “1” with the Same N(R) as the oldest unresolved SREJ frame.
In a primary/secondary Station, since an I or S format frame sent with the P/F bit set to
“1” has the potential of causing Checkpoint retransmission, a primary/secondary Station
shall not send SREJ frames until it receives at least one in-sequence I frame or it
perceives by time-out that the Checkpoint retransmission will not be initiated by the
remote Station. In a combined Station, since an I or S format frame sent with the F bit
set to “1” has the potential of causing Checkpoint retransmission, a combined Station
shall not send SREJ frames until it receives at least one in-sequence I frame or it
perceives by time-out that the Checkpoint retransmission will not be initiated by the
remote Station.
With respect to each direction of transmission on the data link, one or more “sent
SREJ” exception conditions from a given primary/secondary Station to another
primary/secondary Station may be established at a time. A “sent SREJ” exception
condition shall be cleared when the requested I frame is received.
When a primary/secondary Station perceives by time-out that the requested l frame will
not be received, because either the requested I frame or the SREJ frame was in error
or lost, the SREJ frame may be repeated.
A primary/secondary Station receiving one or more SREJ frames shall, when
appropriate, initiate retransmission of the individual l frames indicated by the N(R)
contained in each SREJ frame. After having retransmitted the frames above, new B
frames may be transmitted subsequently if they become available.
When a primarykecondary Station receives and actions one or more SREJ frame
each with the F bit (Primar-y Station) or P bit (secondary Station) set to “0”’ it shall
disable actioning of the next SREJ frame if that frame has the F bit (primary Station) or
P bit (secondary Station) set to “1” and has the same N(R), (i.e., same value and same
numbering cycle) as the previously actioned SREJ frame, and if the resultant
retransmission
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