ETSI ETR 168 ed.1 (1995-01)

SLOVENSKI STANDARD
SIST-TP ETSI/ETR 168 E1:2005
01-april-2005
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Broadband Integrated Services Digital Network (B-ISDN); Digital Subscriber Signalling

System No. two (DSS2) protocol; Guidelines for the interpretation of ETS 300 443-1 (ITU

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and the

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.

Foreword .......................................................................................................................................................5

1 Scope ..................................................................................................................................................7

2 References..........................................................................................................................................7

3 Abbreviations.......................................................................................................................................7

4 Description ..........................................................................................................................................8

5 Bearer Class indications in the Broadband bearer capability information element .............................8

6 Reporting of status ..............................................................................................................................9

7 Compatibility of states .......................................................................................................................10

8 Terminology: "Release", "Capability Set", "Phase"............................................................................10

Annex A: Bibliography ............................................................................................................................12

History..........................................................................................................................................................14

This ETSI Technical Report (ETR) was produced by the Signalling Protocols and Switching (SPS)

Technical Committee of the European Telecommunications Standards Institute (ETSI).

ETRs are informative documents resulting from ETSI studies which are not appropriate for European

Telecommunication Standard (ETS) or Interim European Telecommunication Standard (I-ETS) status. An

ETR may be used to publish material which is either of an informative nature, relating to the use or the

application of ETSs or I-ETSs, or which is immature and not yet suitable for formal adoption as an ETS or

ETS 300 443-1 provides the Broadband Integrated Services Digital Network (B-ISDN) user-network

interface layer 3 specification for basic call control protocol. It is an endorsement of ITU-T

This ETR gives some additional information for the interpretation of these documents by providing

NOTE: At the time of publication of this ETR, ITU-T Recommendation Q.2931 had not yet

been published by ITU. Therefore, this ETR is based on ITU-T Study Group 11 report

This ETSI Technical Report (ETR) provides guidelines for the interpretation of ETS 300 443-1 [1] which

specifies the layer 3 basic call protocol in the Broadband Integrated Services Digital Network (B-ISDN) at

It is intended to provide for some background information on some major questions which may arise in the

The general description of the B-ISDN Release 1 user-network interface layer 3 specification for basic call

control protocol is provided by ETS 300 443-1 [1] which is an endorsement of ITU-T Recommendation

This ETR gives some additional information for the interpretation of these documents by providing

guidelines for the interpretation of various detailed aspects. In particular, it covers:

- Bearer Class indications in the Broadband Bearer Capability (B-BC) information element (see ITU-T

- reporting of status (see ITU-T Recommendation Q.2931 [2], subclauses 4.4.1, 4.5.1, 5.6, 5.7 and

- compatibility of call states (see ITU-T Recommendation Q.2931 [2], subclauses 5.6.4, 5.6.12 and

It should be noted that the contents of this ETR are of tutorial nature, and does not impose any restrictions

To avoid duplications, the following text makes reference only to ITU-T Recommendation Q.2931 [2].

ITU-T Recommendation Q.2931 [2] allows for the indication of Bearer Classes "BCOB-A", "BCOB-C" and

"BCOB-X" in the B-BC information element (see table 4-8/Q.2931) within the scope of Release 1 of

B-ISDN. These indications refer to the "Broadband Connection-oriented Bearer services" of types A, C,

and X, respectively, as specified in CCITT Recommendation F.811 [3] and ITU-T Recommendation

Bearer Class C refers to connection-oriented services with variable bit rate (and no requirement for end-

to-end timing). These services may be indicated for B-ISDN Release 1, however, it should be noted that

Release 1 only allows for traffic indications via the peak cell rate values of a connection. This means that,

although BCOB-C services can be indicated according to ITU-T Recommendation Q.2931 [2], these

services may get only some limited support within Release 1 which will not take advantage of the bursty

nature of their traffic flow. In particular, the network may allocate resources (as if Bearer Class A was

requested) and therefore allocate resources only on the basis of the peak cell rate.

If, within the scope of Release 1, a user indicates BCOB-C in the B-BC information element together with

additional traffic parameters in the ATM traffic descriptor information element beyond the peak cell rate

indications, the call will be rejected (mandatory information element content error).

Additional traffic parameters for the support of BCOB-C services will be provided within the scope of

NOTE: In particular, such parameters will be specified within the scope of work item DE/SPS-

The same restrictions as indicated for Bearer Class C also apply for indications of Bearer Class X, i.e.

indication of a user-defined connection-oriented bearer class. Also for BCOB-X, only the peak cell rate

ITU-T Recommendation Q.2931 [2] does not contain a codepoint for Bearer Class D (or "BCLB",

Broadband Connectionless Bearer service), although the support of such connectionless bearer services

has been defined as part of Release 1 by ITU-T SG 13. However, these services will be supported in

Release 1 via semi-permanent connections providing access to connectionless servers, and therefore do

not require on-demand signalling functions. Therefore, no codepoint for Bearer Class D is provided within

Within clause 5 (particularly subclauses 5.6 and 5.7) and annex A of ITU-T Recommendation Q.2931 [2],

the text and the SDL diagrams often refer to the reporting of status. It is already known from N-ISDN

signalling that some clarifications on the reporting of status are needed to avoid interoperability problems,

particularly with regard to the question: "Call state before or after processing a message?".

During the ITU-T SG 11 meeting in Geneva in December 1993, some clarifications have been reached on

these questions. However, these clarifications are only partly reflected within the procedure text (cf.

Q.2931 [2], subclauses 5.6.7.1, 5.6.8.1 and 5.7.2, item d)), and the detailed reporting of status can only be

derived from the SDL diagrams (cf. Q.2931 [2], annex A), where the clarifications have been incorporated.