SIST ETS 300 124 E1:2003

SLOVENSKI STANDARD
SIST ETS 300 124 E1:2003
01-december-2003
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Terminal Equipment (TE); Attachment requirements for Data Terminal Equipment (DTE)
to connect to Packet Switched Public Data Networks (PSPDN) using CCITT
Recommendation X.25 (1984) interface; Requirements applicable to DTEs subscribing to
Multilink operation
Ta slovenski standard je istoveten z: ETS 300 124 Edition 1
ICS:
33.040.40 Podatkovna komunikacijska Data communication
omrežja networks
SIST ETS 300 124 E1:2003 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST ETS 300 124 E1:2003

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SIST ETS 300 124 E1:2003
EUROPEAN ETS 300 124
TELECOMMUNICATION April 1991
STANDARD
ICS: 33.020
DTE, PSPDN, Multilink operation
Key words:
Attachment requirements for Data Terminal Equipment (DTE)
to connect to Packet Switched Public Data Networks (PSPDN)
using CITT Recommendation X.25 (1984) interface
Requirements applicable to DTEs subscribing to Multilink
operation
(the text of this ETS may be utilized for the establishment of Annex I of NET 2)
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
F-06921 Sophia Antipolis CEDEX - FRANCE
Postal address:
650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE
Office address:
c=fr, a=atlas, p=etsi, s=secretariat - secretariat@etsi.fr
X.400: Internet:
Tel.: +33 92 94 42 00 - Fax: +33 93 65 47 16
Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and the
foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 1991. All rights reserved.
New presentation - see History box

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Whilst every care has been taken in the preparation and publication of this document, errors in content,
typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to
"ETSI Editing and Committee Support Dept." at the address shown on the title page.

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Contents
Foreword.5
1 Normative references .7
2 Definitions.7
3 Symbols and abbreviations.7
4 Multilink procedure (MLP) .7
4.1 General.7
4.2 Tests .8
4.2.1 Verification of MLP setup phase .9
4.2.1.1 The system under test (sut) does not initialize the MLP.10
4.2.1.1.1 Initialization through L1, L2 in DM. (MN(S) = 0).10
4.2.1.1.2 Initialization through L1, L2 in DM.(MN(S)>0).10
4.2.1.1.3 Initialisation through L1, MLP frame with C=1 is sent
immediately after MLP frame when R=1. L2 in DM.10
4.2.1.1.4 Initilization through L1, L2 active.11
4.2.1.1.5 Initialization through L1, confirmation by L2.11
4.2.1.2 The sut does not initialize the MLP.12
4.2.1.2.1 Initialization through L1, L2 in DM. (MN(S) = 0) .12
4.2.1.2.2 Initialization through L1, L2 in DM. (MN(S)>).12
4.2.1.2.3 Initialization through L1, MLP frame when C=1 is sent
immediately after MLP frame when R=1. L2 in DM.12
4.2.1.2.4 Initialization through L1, L2 active.13
4.2.2 Verification of MLP re-routing conditions .14
4.2.2.1 Disconnect Mode (DM) condition .15
4.2.2.2 Frame reject (FRMR) condition.16
4.2.2.3 Retransmission condition.17
4.2.2.4 Busy condition .18
4.2.2.5 Waiting aknowledgement condition.19
4.2.3 Verification of MLP timers.20
4.2.3.1 The DTE does not initialise the MLP. 21
4.2.3.2 The DTE does initialise the MLP .21
History.22

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Foreword
This European Telecommunication Standard (ETS) has been produced by the Terminal Equipment (TE)
Technical Committee of the European Telecommunications Standards Institute (ETSI).
This ETS contains attachment requirements applicable to packet mode Data Terminal Equipment (DTEs)
which subscribe to the optional application of multilink operation. These attachment requirements are
additional to those contained in the main body of NET 2 [1].
The text of this ETS may be utilised for the establishment of Annex I to NET 2 [1]. Copies of NET 2 [1]
may be obtained from:
CEPT Liaison Office
Seilerstrasse 22
CH - 3008 Bern
Telephone: +41 31 62 20 81
Facsimile: +41 31 62 20 78
Telex: 911089 CEPT CH

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1 Normative references
This European Telecommunication Standard (ETS) incorporates by dated or undated reference, provisions
from other publications. These normative references are cited at the appropriate places in the text and the
publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of
these publications apply to this ETS only when incorporated in it by amendment or revision. For undated
references the latest edition of the publication referred to applies.
[1] NET 2 (First edition, 1988): "Approval requirements for data terminal equipment
to connect to packet switched public data networks using CCITT
Recommendation X.25 (1984) interface".
[2] CCITT Recommendation X.25 (1984): "Interface between data terminal
equipment (DTE) and data circuit-terminating equipment (DCE) for terminals
operating in the packet mode and connected to public data networks by
dedicated circuit".
2 Definitions
For the purpose of this ETS the definitions provided in NET 2 [1] and CCITT Recommendation X.25 [2]
shall apply.
3 Symbols and abbreviations
DTE Data Terminal Equipment
SLP Single Link Procedure
MLP Multilink Procedure
LAPB Link Access Procedure Balanced
PDU Protocol Data Unit
DM Disconnected Mode
sut system under test
SABM Set Asynchronous Balanced Mode
DISC Disconnect
FRMR Frame Reject
RNR Receive Not Ready
RR Receive Ready
4 Multilink procedure (MLP)
4.1 General
This subclause contains the additional requirements to be satisfied by a DTE which subscribes to the
multilink procedure.
The requirements established for Single Link Procedure (SLP) in section 9 of NET 2 [1] or in the
supplement for modulo 128 operation are applicable. The only difference is in respect of the address field
of Link Access Procedure Balanced (LAPB) frames where the encoding shall be as reflected in CCITT
Recommendation X.25 (1984), paragraph 2.4.2 [2], for multilink operation.

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4.2 Tests
To execute a test, the tester shall attempt to force the DTE to an appropriate phase or condition by
transmitting a particular Protocol Data Unit (PDU) or a sequence of PDUs. However, some DTEs may
initialize the link or send a particular PDU that requires an appropriate answer from the tester to be in
accordance with the protocol procedures.
To represent those situations in the test descriptions, the following notation shall be used:
- PDUs within [ ] denote optional PDUs from the DTE that shall not require a
specific answer from the tester;
- PDUs within ( ) denote optional PDUs from the DTE that shall require a specific
answer from the tester according to the protocol procedures.
The following requirements shall be applied along the whole section:
a) in many tests the DTE has to transmit an I-frame. The DTE can be forced to
transmit an I-frame, e.g. by receiving:
- RESTART INDICATION (in state r1),
- RESET INDICATION on an LC, as assigned as a PVC, in any state
except d2 and d3,
- CLEAR INDICATION on an LC, assigned as an SVC, in any state except
p.6 and p.7.
It depends on the characteristics of the DTE what packet should be used;
b) if for any reason both SLPs become in Disconnected Mode (DM), the MLP
resetting can be possible. If MLP were reset then MLP frames to be transmitted
by the DTE may be lost.
c) the following tests are defined under the assumption that both SLPs are
configured with the same system parameters.

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4.2.1 Verification of MLP setup phase
A preamble verification sequence shall be executed before each test in both lines (L1 and L2) which link
the DTE and the Tester:
�˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜¿
‡   Tester                DTE        ‡
‡                               ‡
‡L1&L2   DISC/P=1 --------------->             ‡
‡                               ‡
‡          <-------------- UA/F=1 or DM/F=1  L1&L2‡
�˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜�
A post-test sequence shall be executed after each test to verify the correct status of the DTE:
�˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜¿
‡   Tester                DTE        ‡
‡                               ‡
‡L1 or L2 I, MN(O) ----------->               ‡
‡                               ‡
‡               <---------- I, MN(O) L1 or L2 ‡
‡                               ‡
‡L1&L2   RR/P=1  ----------->               ‡
‡                               ‡
‡               <---------- RR/F=1  L1&L2   ‡
‡                               ‡
‡                               ‡
‡NOTE: The tester shall acknowledge each MLP frame sent by the‡
‡   DTE with an SLP frame (I or RR) on the same link on  ‡
‡   which the MLP frame was received.           ‡
�˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜�

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4.2.1.1 The system under test (sut) does not initialize the MLP
4.2.1.1.1 Initialization through L1, L2 in DM. (MN(S) = 0)
<-------------- (SABM/P1) L1 & L2
L1 SABM/P=1 --------------------->
L1 (UA/F=1) --------------------->
L2 (DM/F=1) --------------------->
<-------------- UA/F=1 L1
L1 MLP/R=1 (MN(S)=0) ----------->
<-------------- [RR] L1
<-------------- MLP/R=1 L1
L1 RR --------------------->
L1 MLP/C=1 --------------------->
<-------------- [RR] L1
<-------------- MLP/C=1 L1
4.2.1.1.2 Initialization through L1, L2 in DM.(MN(S)>0)
<-------------- (SABM/P1) L1 & L2
L1 SABM/P=1 --------------------->
L1 (UA/F=1) --------------------->
L2 (DM/F=1) --------------------->
<-------------- UA/F=1 L1
L1 MLP/R=1 (MN(S)>0) ----------->
<-------------- [RR] L1
<-------------- MLP/R=1 L1
L1 RR -------------------->
L1 MLP/C=1 -------------------->
<-------------- [RR] L1
<-------------- MLP/C=1 L1
4.2.1.1.3 Initialisation through L1, MLP frame with C=1 is sent immediately after MLP frame
when R=1. L2 in DM
<-------------- (SABM/P1) L1 & L2
**)
L1 SABM/P=1 --------------------->
L1 (UA/F=1) --------------------->
L2 (DM/F=1) --------------------->
<-------------- UA/F=1 L1
L1 MLP/R=1 --------------------->
L1 MLP/C=1 --------------------->
<-------------- MLP/R=1 L1
<-------------- [MLP/C=1] L1
L1 RR --------------------->
<-------------- MLP/R=1 L1 *)
L1 MLP/R=1 --------------------->
<-------------- MLP/C=1 L1
L1 MLP/C=1 --------------------->
*) MT3 expires.
**) If the DTE reacts on R=1 MLP frame before treating C=1 MLP frame MT3 shall not expire. In that
case the test shall be considered successful.

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4.2.1.1.4 Initilization through L1, L2 active
<--------------- (SABM/P=1) L1 & L2
L1 & L2 SABM/P=1 ---------->
L1 & L2 (UA/F=1) ---------->
<--------------- UA/F=1 L1 & L2
L1 MLP/R=1 ---------->
�˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜¿
‡<-------------- RR         L1‡
‡<-------------- MLP/R=1      L2‡
�˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜�
**)
or
�˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜¿
‡<-------------- [RR]        L1‡
‡<-------------- MLP/R=1      L2‡
�˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜�
*)
RR ---------->
L1 MLP/C=1 ---------->
<--------------- [RR] L1
<--------------- MLP/C=1 L1 or L2
4.2.1.1.5 Initialization through L1, confirmation by L2
<---------------- (SABM/P=1) L1 & L2
L1 & L2 SABM/P=1 ---------->
L1 & L2 (UA/F=1) ---------->
<---------------- UA/F=1 L1 & L2
L1 MLP/R=1 ---------->
�˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜¿
‡<-------------- [RR]        L1‡
‡<--
...