1、ITU-T RECflN*I.SBO 95 m 4Bb2591 Ob12042 589 m INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU INTEGRATED SERVICES DIGITAL NETWORK (ISDN) INTERNETWORK INTERFACES 1.580 (1 1 /95) GENERAL ARRANGEMENTS FOR AND 64 kbis BASED ISDN INTERWORKING BETWEEN B-ISDN ITU
2、-T Recommendation 1.580 (Previously “CCITT Recommendation”) ITU-T RECMN*I.SBO 95 W 48b259L Ob32043 41.5 FOREWORD The ITU-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (ITU). The ITU-T is responsible for studying technical, operating an
3、d tariff questions and issuing Recommen- dations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the IT-T Study Groups which, in their turn,
4、produce Recommendations on these topics. The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1 (Helsinki, March 1-12, 1993). ITU-T Recommendation 1.580 was revised by ITU-T Study Group 13 (1993-1996) and was approved under the WTSC
5、 Resolution No. 1 procedure on the 2nd of November 1995. NOTE In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency, O ITU 1996 Ali rights reserved. No part of this publication may be repr
6、oduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the IT. m Lt8625L Ob32044 351 = CONTENTS Introduction Scope Communication scenarios Interworking configurations . Concatenation of 64 kbit/s based ISDNs
7、via B-ISDN Concatenation of B-ISDNs via 64 kbi/s based ISDN B-ISDN to 64 kbit/s based ISDN interconnection Decomposition of 64 kbit/s based ISDN into component parts Relationship of connections between 64 kbit/s based ISDN and B-ISDN . Interworking functional requirements for 64 kbit/s based ISDN se
8、rvices Emulation of 64 kbits based ISDN network components . 4.1 4.2 4.3 4.4 Interworking functional requirements 6.1 Annex A . Interworking scenarios to provide 64 kbit/s based ISDN services to a B-ISDN user . A.l Scenario A A.2 Scenario B . Annex B - Comparison of Broadband Connection Oriented and
9、 64 kbit/s based ISDN bearer services . Annex C - OAM information mapping for interworking B-ISDN and 64 kbits based ISDN . Possible OAM information mapping Appendix I - Access to specific B-ISDN services from a 64 kbit/s based ISDN . Access to other specific B-ISDN services from 64 kbWs based ISDN
10、QOS experienced by the 64 kbit/s based ISDN user C.l Interworking scenarios C.2 1.1 1.2 1.3 Access to BCDBS from 64 kbit/s based ISDNs . Recommendation 1.580 (W95) Page 1 1 1 1 2 2 3 3 4 6 6 13 15 15 16 19 23 23 23 28 28 29 30 i ITU-T RECMN*I-580 75 m 4862593 Ob32045 298 m SUMMARY During the evoluti
11、on to B-ISDN implementations, arrangements must be determined for interworking B-ISDN services and networks with existing services and networks. This Recommendation identifies the arrangements and principles for interworking between B-ISDN and 64 kbitls based ISDN. Interworking with other than 64 kb
12、itls based ISDN is beyond the scope of this Recommendation. II Recommendation 1.580 (11/95) ITU-T RECMNUI-SBO 95 W 4862591 ObL204b 124 = Recommendation 1.580 GENERAL ARRANGEMENTS FOR INTERWORKING BETWEEN B-ISDN AND 64 kbit/s BASED ISDN (Helsinki, 1993; revised in 1995) 1 Introduction It is recognize
13、d that B-ISDN may be implemented in a variety of ways according to specific national situations. In these evolutionary phases, appropriate arrangements must be developed for the interworking of services on B-ISDN and services on other networks, and in particular. between B-ISDN and 64 kbitls based I
14、SDN services. The evolution to B-ISDN should ensure the continued support of existing terminals and services. That is, many terminals developed for 64 kbit/s based ISDN should be able to be connected to B-ISDN. Also, services currently provided by 64 kbits based ISDN should be provided through B-ISD
15、N interworking configurations. 2 Scope The purpose of this Recommendation is to identify the general arrangements and principles for the interworking between B-ISDN and 64 kbit/s based ISDN. The functions and other requirements for the interworking between B-ISDN and 64 kbit/s based ISDN for the pro
16、vision of ISDN bearer services are also defined in this Recommendation. Interworking with other networks than 64 kbit/s based ISDN is beyond the scope of this Recommendation. Teleservices and Supplementary services to be supported by B-ISDN interworking configurations require further study. The case
17、 where broadband capabilities are available end-to-end is outside the scope of this Recommendation and should be described in other Recommendations. 3 Communication scenarios Considering the interworking configuration of ISDN having both 64 kbitfs based ISDN capabilities and broadband capabilities,
18、the communication scenarios are identified as shown in Figure 1: - Scenario I is an interconnection scenario between B-ISDN and 64 kbits based ISDN. - Scenario II is a network concatenation interworking scenario, but the interfaces and services are the same as those which are currently provided by 6
19、4 kbit/s based ISDN. In Scenario III, the service capabilities provided between broadband user access points are restricted to 64 kbit/s based ISDN capabilities. In Scenario IV, broadband capabilities are available end-to-end and services currently provided by 64 kbit/s based ISDN are also supported
20、. The 64 kbitfs based ISDN services provided by this scenario are similar to those provided by Scenarios I and III. The 64 kbit/s based services are provided on B-ISDN interfaces. - - - In Scenario V, end-to-end communication is entirely within the 64 kbits based ISDN. The services available are the
21、 services provided by the 64 kbitfs based ISDN. The services provided by Scenario V will be similar to those provided by Scenarios I and II. Scenarios IV and V are outside the scope of this Recommendation. 4 Interworking configurations Reference configurations described in this clause are purely fun
22、ctional representations of possible interworking configurations. Recommendation 1.580 (lV95) 1 ITU-T RECMN*I.5O 95 W 48b259L Ob12047 Ob0 W . . . C.*. T181821092/dOl IWF Interworking Function TE Terminai Equipment FIGURE 1A.580 Communication scenarios applicable to B-ISDN and 64 kbit/s based ISDN 4.1
23、 Concatenation of 64 kbit/s based ISDNs via B-ISDN Figure 2 shows a reference configuration of concatenation of 64 kbit/s based ISDNs via B-ISDN. This configuration may appear in the evolutionary process towards B-ISDN. With this interworking configuration, the services provided by end-to-end teleco
24、mmunication are those that are currently provided by 64 kbit/s based ISDN. 64 kbiffs based ISDN IWF NVF 64 kbits based Tl818220-92/dO2 FIGURE 2A.580 Reference configuration of concatenation of 64 kbit/s based ISDNs via B-ISDN For interworking between B-ISDN (the ATM part of the network) and 64 kbit/
25、s based ISDN (the non-ATM part of the network), the Interworking Function (IWF) should be defined. 4.2 Concatenation of B-ISDNs via 64 kbit/s based ISDN Figure 3 shows a reference configuration of concatenation of B-ISDNs via 64 kbit/s based ISDN. This configuration may be present in the initial pha
26、ses of evolution towards B-ISDN wherein B-ISDN islands are interconnected via 64 kbit/s based ISDN. The end-to-end services available with this configuration will be limited to B-ISDN services which have a 64 kbit/s based ISDN equivalent. 2 Recommendation ISM (11/95) ITU-T RECMN*I.580 95 4862593 Ob3
27、2OY8 TT7 IWF 64 Kis based IWF FIGURE 3D.580 Reference configuration of concatenation of B-ISDNs via 64 kbih based ISDN 4.3 B-ISDN to 64 kbit/s based ISDN interconnection Figure 4 shows a reference configuration of B-ISDN to 64 kbit/s based ISDN interconnection. This configuration where B-ISDN is int
28、erconnected to 64 kbit/s based ISDN will also provide the services that are currently provided by 64 kbit/s based ISDN. This is intended to provide connectivity between B-ISDN and 64 kbit/s based ISDN users. B-ISDN r4.iit 64 kbiffs based T1818240-9d04 FIGURE 4A.580 Reference configuration of B-ISDN
29、to 64 kbit/s based ISDN interconnection This configuration can be further classified to the following two cases: a) b) where B-TES support 64 kbit/s based ISDN services; and where 64 kbit/s based ISDN TES are connected to B-ISDN. Figure 5 shows these cases and the scope of ISDN bearer services curre
30、ntly provided by 64 kbit/s based ISDN: - The physical configurations for 64 kbit/s based access are defined in Recommendation 1.41 1, and those for broadband access are defined in Recommendation 1.413. - B-ISDN shall include functions of both broadband capabilities and 64 kbit/s based ISDN capabilit
31、ies. - Since the figures are purely functional representations, the IWF can be provided in an inter-exchange as well as in an intra-exchange environment. 4.4 Decomposition of 64 kbit/s based ISDN into component parts This describes decomposition of the 64 kbit/s based ISDN portion of the reference c
32、onfiguration model of 4.1, 4.2 and 4.3. The configuration model below is based on Recommendations X.300 and 1.324 concepts. This model reflects a decomposition of 64 kbitis based ISDN into ISDN (PM), ISDN (CM) and ISDN (FM) portions. A similar decomposition of the B-ISDN is not applicable. This mode
33、l is used to assist in identification of interworking functions and requirements. See Figure 6. 3 Recommendation 1.580 (1Y95) ITU-T RECMN*Im580 95 4862593 Ob32049 933 B-TE) ISDN B- TE) IWF) TE) Figure Z1.411 . 4 T181E25092idE Figure-Z1.413 1. Scope of ISDN bearer Cennces currently provided by 64 kbi
34、is based ISDN B-TE B-TE1 or B-TA +B-TE2fE2. b, TE TE1 orTA+TE2. ) iWF interworking Functim. FIGURE 5A.580 Scope of 64 kbit/s based ISDN bearer services through interworking B-ISDN LFC Local Functional Capabilities CM Circuit Mode FM FrameMode PM PacketMode NOTE - This point could be connected to a T
35、E, or to another WF and a second 64 kbit/s based ISDN, consistent with 4.1,4.2 and 4.3 interworking reference configurations. FIGURE 6i.580 Reference configuration decomposition 5 64 kbits based ISDN connection types are defined in Recommendation 1.340. In the case of interworking between B-ISDN and
36、 64 kbit/s based ISDN, 64 kbit/s based connections are related to broadband connections with appropriate AAL connections. The relationship between 64 kbits based connections and broadband connections is categorized into the following two patterns: Relationship of connections between 64 kbit/s based
37、ISDN and B-ISDN i) One-to-one correspondence Each 64 kbits connection has a one-to-one correspondence to a broadband VPNC connection with an appropriate AAL service class. - Establishment of connections: Switched. semi-permanent, permanent. 4 Recommendation 1.580 (11/95) ITU-T RECMN*Im50 75 4862593
38、0612050 655 - Quality Of Service (QOS) classes: 64 kbit/s based ISDN connection types are related to appropriate broadband QOS classes. Specific QOS class assignment is for further study. Applied broadband bearer service classes: Speech Class A 3.1 kHz audio Class A - Multi-use Class A 64 kbit/s unr
39、estricted Class A Multirate n x 64 kbit/s (n 230) 384, 1536, 1920 kbit/s unrestricted Class A Class A Packet mode Frame mode Class c Class c ii) N-to-one correspondence (N 1 1) Multiple 64 kbit/s based ISDN connections are bundled without distinguishing constituent connections and the bundle corresp
40、onds to one broadband VPNC connection with an appropriate AAL service class. - 64 kbit/s based ISDN connection types: 64 kbit/s based ISDN connections have an N-to-one correspondence (N 1 1) to broadband connections. The case might arise where different 64 kbit/s based ISDN connection types are mixe
41、d in the same bundle corresponding to one broadband connection. - Establishment of connections: Semi-permanent, permanent. - QOS classes: In general, each QOS of a 64 kbiih based ISDN connection does not correspond to the QOS of the corresponding broadband connection. An appropriate broadband QOS is
42、 offered for the unit bundling multiple 64 kbit/s based ISDN connections. - Applied AAL services classes: One AAL service class is associated with one broadband connection. The following categories are identified. In the case where a unique 64 kbit/s based ISDN connection type is bundled: Speech 3.1
43、 kHz audio Class A Class A 64 kbit/s unrestricted 384, 1536, 1920 kbit/s unrestricted Packet mode Class c Class A (Note) Class A (Note) Frame mode Class c NOTE - This may be used for frame mode or packet mode bit streams multiplexed in a 64, 384, 1536 or 1920 kbifs connection. In the case where vari
44、ous 64 kbit/s based ISDN connection types are bundled: - a typical example of this case is where a link is emulated by a broadband connection. This is for further study. Recommendation 1.580 (1l95) 5 ITU-T RECMN*I=580 95 48b259L 0612051 591 6 Interworking functional requirements 6.1 Interworking fun
45、ctional requirements for 64 kbis based ISDN services ISDN bearer services supported by B-ISDN are classified into the following two categories: 1) Broadband specific ISDN bearer services - The services which can only be provided by a network providing end-to-end broadband capabilities. 2) 64 kbit/s
46、based ISDN bearer services - The services which are equivalent to the bearer services currently provided by 64 kbi/s based ISDN, for example speech, 3.1 kHz audio and 64 kbi/s unrestricted bearer service. Based on bearer services supported in the configuration of interworking between B-ISDN and 64 k
47、bifs based ISDN, services can be classified into three categories: i) circuit mode bearer service; ii) packet mode bearer service; and iii) frame mode bearer service. 6.1.1 Interworking functions for circuit mode bearer service Figure 7 shows an example of a circuit mode bearer service interworking
48、model in the configuration of B-ISDN to 64 kbiih based ISDN interconnection. 8-ISDN 64 kbiffs based ISDN CHH ET circuit mode terminai T181828o-Wd07 terminal ET Exchange Termination CHH Channel Handling functionalQ (e.9. switching) FIGURE 7I.580 Example of interworking model between circuit mode term
49、inai and B-ISDN terminal Figure 8 shows circuit mode bearer service interworking in the U-Plane for the reference configuration of B-ISDN to 64 kbit/s based ISDN interconnection. In this case, Broadband Connection Oriented Bearer Service-A (BCOBS-A defined in Recommendation F.811) for circuit emulation in B-ISDN and circuit mode bearer service in 64 kbit/s based ISDN are interworked. The values of each bearer service attribute are specified in Recommendations 1.231 and F.811 (see Annex B). Interworking functions are required to provide the mapping be
