Integrated Services Digital Network (ISDN) – Packet Mode Bearer Service Category Description
|Publication Date:||1 April 1991|
Scope, purpose and application
The International Telegraph and Telephone Consultative Committee (CCITT) Recommendation 1.210 describes the principles for defining Integrated Services Digital Network (ISDN)- basled telecommunication services including the concept of bearer services, teleservices and supplementary services. It also provides the means for the definition and description of such services.
The purpose of this standard is to define a recgmmended set of packet mode bearer services categories, to describe individual packet mode bearer services and to recommend their provision as ISDN-based services in North America. The definitions and descriptions form the basis to define the network capabilities required for the support of ISDN-based packet mode bearer services. Individual packet mode bearer services, from any category, are bursty in character and may, in combination, create congestion on the D channel. The issues of congestion and of mechanisms for dealing with it are not addressed in this standard. Contention between information on SAPI 0 and SAPI 16 is not covered in this standard nor is it explicitly dealt with in ANSI T1.602. In particular, the mechanism for handling non- SAPI 0 information when SAPI 0 information is in contention with it on a D channel needs to be defined.
Bearer service categories are described by prose definitions and descriptions, by attributes and their values and by dynamic descriptions following the description method given in CCITT Recommendation 1.130. The application of the attribute method and the definitions of these attributes and attribute values is given in CCITT Recommendation I.1 40.
The following set of packet mode bearer services categories is currently identified and more may be identified in the future:
a) virtual call and permanent virtual circuit bearer service category;
b) connectionless bearer service category;
c) user signaling bearer service category;
d) frame mode bearer service category.
Only the virtual call and permanent virtual circuit bearer service category is included in this issue.
NOTE - Frame Mode Bearer Services may also provide services similar to virtual call and permanent virtual circuit. The other categories are for further study.
This standard is based on CCITT Recommendation 1.232. The only technical differences between this standard and CCITT Recommendation 1.232 are that this standard mentions D channel congestion (see clause 1, paragraph 2) and this standard mentions permanent virtual circuits on the D channel (see 220.127.116.11.2).