1、CEPT T/GSI*02-02 E W 2326424 0005368 4 W TGS 02-02 Page E 1 Recommendation T/GSI 02-02 (Nice 1985, revised by correspondence, June 1987) BEARER SERVICES Recommendation proposed by the Special Group Integration (GSI) Text of the Recommendation adopted by the “Telecommunications” Commission. “The Euro
2、pean Conference of Posts and Telecommunications Administrations, considering - the common CEPT approach to the ISDN and general CEPT assumptions and policies for the evolution towards - the I. Series Recommendations of the CCITT, as well as other CCITT Recommendations on ISDN, to which - the need fo
3、r CEPT Administrations to have more precise answers to their specific European requirements, i.e. - the need for CEPT Administrations to have as a base a comprehensive set of Recommendations, in order to ISDN, CEPT Administrations have contributed most significantly, to select and further define mat
4、erial from CCITT Recommendations, promote and strengthen European harmonisation, O recommends - to the members of the CEPT, that they evolve their telecommunication networks towards ISDN according to the specifications given in the attached text.” CEPT T/GSI*02-02 E m 232b414 0005369 b I T/GSI 02-02
5、 E Page 2 Recommendation T/GSI 02-0 1 describes the principles for defining telecommunication services supported by an ISDN, including the concept of bearer services, bearer capabilities and teleservices. The purpose of this Recommendation is to describe and define a recommended set of bearer servic
6、es and their associated bearer capabilities to be supported by an ISDN as a basis for defining the network capabilities required. Bearer services are described by a number of attributes. These attributes are described and defined in Recommenda- tion T/GSI 01-05. 1. FRAMEWORK FOR DESCRIBING BEARER SE
7、RVICES SUPPORTED BY AN ISDN Bearer services are described by attributes, which are intended to be independent. They are grouped into three categories: i) information transfer attributes, which characterize the network capabilities for transfering information from one S/T reference point to one (or m
8、ore) other S/T reference point, corresponding to access points 2 and 1 as defined in Recommendation T/GSI 02-01; ii) access attributes, which describe the means for accessing network functions or facilities as seen at one S/T reference point; and iii) general attributes, which deal with the service
9、in general. Infomation transfer attributes - attributes /- -. /- ISDN Access attributes Access attributes Figure 1 (T/GSI 02-02). Relationship between the groups of attributes and fields of applicability. Table 1 (T/GSI 02-02) gives the list of the attributes. For the definitions and possible values
10、 of these attributes, see Recommendation T/GSI 01-05. Information transfer attributes 1. Information transfer mode 2. Information transfer rate 3. Information transfer capability 4. Structure 5. Establishment of communication 6. Communication configuration 7. Symmetry 8. Access channel and rate 9. A
11、ccess protocol Access attributes (Note) General attributes 10. Supplementary services provided 11. Quality of service 12. Interworking possibilities 13. Operational and commercial Note. Different access attributes may apply at each of the (two or more) network interfaces involved in the use of a bea
12、rer service. Table 1 (T/GSI 02-02). List of attributes. Edition of October 31, 1987 Figure 2 (T/GSI 02-02) presents a list of possible values for each attribute. Where options exist for a given attribute, the selection is subject to agreement between the customer and the Administration, or RPOA. Acc
13、ording to Recommendation T/GSI 02-01, the bearer capability defines the technical features of a bearer service as they appear to the user at the S/T reference point. For the time being, the bearer capability is characterized by information transfer and access attributes. A bearer capability is assoc
14、iated with every bearer service. CEPT T/GSI*02-02 E T/GSIT/GSI T/S TIS 04-02/lL02/4 46- I 46- I 2326414 0005370 2 Unrestricted information digital OFS* 3.1 kHz 7 kHz 15 kHz Video Speech audio audio audio I I I I Service data unit integrity (Note 2) 8 kHz integrity I Unrestructured Demand Reserved D(
15、16) D(64) B HO H11 HI2 Others for further study TIGSI 02-02 E Page 3 Possible values of attributes Attributes (Note 31 Circuit Packet I Information transfer attributes 1. Information transfer mode Bit rate (kbit/s) I Troughput 2. Information transfer rate I Option for further study 384 1536 1920 Oth
16、er values for 64 I I I I further study 3. Information transfer capability 4. Structure 5. Establishment of communica- tion (Note 5) Permanent Point-to-point Multipoint Broadcast (Note 1) 6. Communication configuration Bidirectional symmetric Bidirectional asymmetric I Uni- directional 7. Symmetry Ac
17、cess attributes 8. Access channel and rate 9.1 Signalling access protocol layer 1 (Note 04.02l 4) III Others FS TIS 46-20 I III Others FS 9.2 Signalling access protocol 9.3 Signalling access protocol layer 3 46-30 I I I I x-25 I I Others FS I G.711 I Others FS 9.4 Information access protocol layer 1
18、 Others FS 9.5 Information access protocol layer 2 9.6 Information access protocol layer 3 T.70 I X.25 I Others FS I General attributes 10. Supplementary services provi- Under study I i i. tfaiity of service 12. Interworking possibilities 13. Operational and commercial * OFS: Others Further Study. N
19、ote I. The characterization of the information transfer configuration attribute “broadcast” is for further study. Note 2. The need for a “data sequence integrity” attribute is for further study. Note 3. The attributes are intended to be independent of each other. They are defined in T/GSI 01-05. Not
20、e 4. The inclusion of T/GSI 04-02/1 implies the support of non-ISDN CCITT standardized services (e.g. at X.l rates). The necessary user-network signalling is provided in Recommendation T/S 46-30. Figure 2 (T/GSI 02-02). Values for each Bearer Service attribute. Edition of October 31. 1987 CEPT T/GSI
21、*02-02 E 2326434 0005373 4 T/GSI 02-02 E Page 4 2. 2.1. 2.1.1. DESCRIPTION OF BEARER SERVICES This section describes several bearer services accessed via the standard network access provided by an ISDN. The identification and description of possible additional services such as subrate services are l
22、eft for further study. These possible additional services would not lead to any additional requirements to those already identified for physical characteristics of interfaces to be applied at reference points S and/or T. The description of the bearer services is based upon the list of attributes as
23、given in Figure 2 (T/GSI 02-02). The information transfer attributes 1-4 are called “Dominant attributes”. They are used to identify a particular bearer service category. Information transfer attributes 5-7 are called “Secondary attributes”. They are used to identify individual bearer services withi
24、n one category. “Access attributes” as well as “General attributes” are used to further specify an individual bearer service. They are called “Qualifying attributes”. The principles of categorizing bearer services are presented in Figure 3 (T/GSI 02-02). information transfer attributes 1. Informatio
25、n transfer mode 2. Information transfer rate 3. Information transfer capability 4. Structure 5. Establishment of communication 6. Communication configuration 7. Symmetry Access attributes 8. Access channel and rate 9.1 Signalling access protocol 9.2 Information access protocol General attributes 10.
26、 Supplementary services provided Il. Quality of service 12. Interworking possibilities 13. Operational and commercial Dominant +, Bearer service attributes categories 1 Individual bearer (in the category) Secondary +, attributes 1 Qualifying attributes Further specifies +, the individual bearer serv
27、ices Figure 3 (T/GSI 02-02). Attribute categories. Circuit-mode bearer services These bearer services are typically characterized by the provision of user information over one type of channel and signalling over another type of channel. The possible use of the channel which conveys signalling inform
28、ation also to provide user-to-user informa- tion transfer during a call is for further study. Circuit-mode 64 kbitls unrestricted 8 kHz structured bearer service category An unrestricted bearer service provides information transfer without alteration between SIT reference points. It may, therefore,
29、be used to support various user applications. Examples include: 1) speech (Note); 2) multiple subrate information streams multiplexed into 64 kbit/s by the user; 3) transparent access to a X.25 public network (Recommendation X.3 1). User information is transferred over a B channel: signalling is pro
30、vided over a D channel. Note. The use of this bearer service for speech application may be possible, depending on the user equipment features (e.g. speech coder law, echo cancellor device .). Attributes/values Information transfer attributes 1. Mode: circuit 2. Rate: 64 kbit/s 3. Information transfe
31、r: unrestricted 4. Structure: 8 kHz integrity 5. Establishment: demand/reserved/permanent 6. Configuration: point-to-point/multipoint 7. Symmetry: bidirectional symmetric/unidirectional - Edition of T/GSI 04 Recommendations for D- channel For further study (may be different from paragraph 2.1.1.) 2.
32、1.3. Circuit-mode 64 kbitls, 8 kHz structured bearer service category, usable for 3.1 kHz audio information transfer This bearer service provides the transfer of 3.1 kHz bandwidth audio information such as e.g. voice band data via modems (Note I); group I, II and III facsimile information and speech
33、. The digital signal at the SIT reference point is assumed to conform to the internationally agreed encoding laws for speech (e.g. A-law). Connections provided for this service should not restrict the transmission of the information indicated above. This means that the network may include signal pro
34、cessing techniques provided; they are appropriately modified or functionally removed prior to information transfer. User information is transferred over a B channel, signalling and/or OAM information may be provided over a D channel. Attributes/values Information transfer attributes 1. Mode: circuit
35、 2. Rate: 64 kbitls 3. Information transfer: 3.1 kHz audio 4. Structure: 8 kHz integrity 5. Establishment: demand/reserved/permanent 6. Configuration: point-to-point/multipoint 7. Symmetry: bidirectional symmetric/unidirectional 8. Access channel: B for user information, D for signalling and/or oper
36、ational, administrative and maintenance (OAM) messages 9. Access protocol: Recommendation G.711 for B channel; T/GSI 04 Recommendations for D channel Access attributes General attributes 10. Supplementary services provided 1 1 1. Qality of service 12. Interworking possibilities I for further study 1
37、3. Operationaland commercial _ Note 1. The maximum modem bitrate that can be supported by this bearer service depends on the modulation standard employed and on the transmission performance within or between different Administrations. The extent of support is a network or bilaterally agreed matter.
38、Edition of October 31, 1987 T/GSI 02-02 E Page 6 2.1.4. Circut-mode alternate speechll kbitls unrestricted, 8 kHz structured bearer service category This service is similar to both the unrestricted and speech 64 kbit/s circuit-mode bearer services but provides for the alternate transfer of either vo
39、ice or unrestricted digital information at 64 kbit/s within the same call. Attributes/values Information transfer attributes 1. Mode: circuit 2. Rate: 64 kbitls 3. Information transfer capability: alternately speech or unrestricted digital information (Note 1) 4. Structure: 8 kHz integrity 5. Establ
40、ishment: demand/reserved/permanent 6. Configuration: point-to-point/multipoint 7. Symmetry: bidirectional symmetric 8. Access channel: B for user information. D for signalling (Note 2). 9. Access protocol: T/GSI 04 Recommendations for D channel signalling Access attributes General attributes 10. Sup
41、plementary services provided 1 I for further study 11. Qality of service (Note-3) 12. Interworking possibilities 13. Operationaland commercial Note I. The need for the transfer of 3.1 kHz audio is for further study. Note 2. For reserved/permanent service the operational, administrative and maintenan
42、ce messages (OAM) related to these services may be conveyed over the D channel. Note 3. A short service changeover time (with a high probability of not being exceeded) has been tentatively identified as a requirement. Circuit-mode alternate speech13.1 kHz audio, 8 kHz structured bearer service categ
43、ory This service provides for the alternate transfer of either speech or 3.1 kHz audio information within the same call. Attributes/values Information transfer attributes 2.1.5. 1. Mode: circuit 2. Rate: 64 kbitls 3. Information transfer: alternately speechl3.1 kHz audio 4. Structure: 8 kHz integrit
44、y 5. Establishment: demand/reserved/permanent 6. Configuration: point-to-pointlmultipoint 7. Symmetry: bidirectional symmetric 8. Access channel: B for user information. D for signalling (Note 1). 9. Access protocol: T/GSI 04 Recommendations for D channel signalling Access attributes General attribu
45、tes 10. Supplementary services provided 1 I for further study 11. Quality of service (Note 2) 12. Interworking 13. Operational-and commercial 1 Note I. For reserved/permanent service, OAM related messages may be conveyed over the D channel. Note 2. A short service changeover time (with a high probab
46、ility of not being exceeded) has been tentatively identified as a requirement. Edition of October 31, 1987 CEPT T/GSI*02-02 E 2326434 0005374 T TIGSI 02-02 E Page 7 2.1.6. Circuit-mode 384 kbit/s unrestricted, 8 kHz structured bearer service category This bearer service provides the unrestricted tra
47、nsfer of 384 kbit/s user information over a HO channel at the S/T reference point. The transfer of OAM information for reserved and permanent services may be provided over a D channel in the same or in another interface structure. Attributes/values Information transfer attributes 1. Mode: circuit 2.
48、 Rate: 384 kbit/s 3. Information transfer: unrestricted 4. Structure: 8 kHz integrity 5. Establishment: demand/reserved/permanent 6. Configuration: point-to-point/multipoint 7. Symmetry: bidirectional symmetric/bidirectional asymmetric/unidirectional (Note) Note. Bidirectional asymmetric, unidirecti
49、onal and demand attribute are under study. Access attributes 8. Access channel: HO (384) for user information, D(16) or D(64) for OAM information 9. Access protocol: T/GSI 04 Recommendations for D channel signalling General attributes 10. Supplementary services provided 1 11. Quality of service 12. Interworking possibilities I for further study 13. Operational and commercial 1 Circuit-mode 1,536 kbitls unrestricted, 8 kHz structured bearer service category Note. This bearer service category will not be provided for use between customers belonging to different European ISD
