1、CCITT RECMN*F-812 92 4862591 0575779 2b9 INTERNATIONAL TELECOMMUNICATION UNION CCITT ME INTERNATIONAL TELEGRAPH AND TELEPHONE CONSULTATIVE COMMITTEE F.812 (08/92) TELEMATIC, DATA TRANSMISSION, ISDN BROADBAND, UNIVERSAL, PERSONAL TELECOMMUNICATIONS AND TELECONFERENCE SERVICES OPERATIONS AND QUALITY O
2、F SERVICE BROADBAND CONNECTIONLESS DATA BEARER SERVICE Recommendation F.812 CCITT RECMN*F=812 92 m 4862591, 0575780 T8O m FOREWORD The CCITT (the International Telegraph and Telephone Consultative Committee) is a permanent organ of the International Telecommunication Union (rnr). CCIT is responsible
3、 for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The Plenary Assembly of CCIT which meets evety four years, establishes the topics for study and approves Recommendations prepared by its S
4、tudy Groups. The approval of Recommendations by the members of CC between Plenary Assemblies is covered by the procedure laid down in CCIT Resolution No. 2 (Melbourne, 1988). Recommendation F.812 was prepared by Study Group I and was approved under the Resolution No. 2 procedure on the 4th of August
5、 1992. CCIIT NOTES 1) telecommunication administration and a recognized private operating agency. 2) In this Recommendation, the expression “Administration” is used for conciseness to indicate both a A list of abbreviations used in this Recommendation can be found in Annex B. O ITU 1993 ,a i .s All
6、rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. - CCITT RECMN*F.832 92 m 4862593 0575783 937 m Recommendation F.812 BROADBAND CONNECTION
7、LESS DATA BEARER SERVICE (1992) 1 Definition A B-ISDN connectionless data service is defined as a service which aiiows the transfer of information among service subscribers without the need for end-to-end call establishment procedures between users. 2 Description 2.1 General description This is a pu
8、blic packet-switched service that provides for the transfer of variable-length data units at high speed without the need for cai1 establishment procedures between users, These data units can be transferred from a single source to a single destination, or from a single source to multiple destinations
9、. Each data unit includes a source address validated by the network. One generic feature of a B-ISDN connectionless bearer service is that it may include broadcasting capabilities. The B-ISDN connectionless data bearer service uses addresses based on the E.164 ISDN numbering plan. For multicast comm
10、unication an address scheme using group addressing is required. Group addressing is a mechanism which allows for the transmission of the same data unit to several intended recipients. A group address is an address used to represent the set of individual addresses that identify the destinations of a
11、group addressed data unit. The source address used in a group addressed data unit may be one of the individual addresses. The B-ISDN connectionless data bearer service is designed such that, under normal conditions, subscribers end-to-end protocols would not require changes. This allows users commun
12、ications architectures as well as the applications built on top of the connectionless service to remain intact. This service is offered on the B-ISDN on ATM connections between the subscriber and a connectionless service node named “connectionless server”, as it is defined in Recommendation 1.21 1.
13、This service will be supported on the B-ISDN user-network interface (UNI) based on asynchronous tranfer mode (ATM). 2.2 Specific terminology 2.2.1 Point-to-point Refer to Recommendation 1.210. 2.2.2 Broadcast Unidirectional communication from a single source entity to an unlimited number of unspecif
14、ied destination entities. 2.2.3 Multicast Unidirectional communication from a single source entity to a limited number of specified destination entities. Recommendation F.812 (08/92) 1 CCITT RECMN*F-832 72 m 4862573 0575782 853 m Note - Examples of communication configurations related to these terms
15、 in 0 2.2.2 and 2.2.3 can be found in Table 1D.812. I I I I T0102990-93 TABLE 1E.812 Examples of communication configuration 2.2.4 Protocol data unit (PDU) A block of data consisting of all information for end-to-end transmission (user data, addressing information and service parameters). 2.2.5 CLPD
16、U Connectionless protocol data unit (see 8 2.2.4). 2.2.6 L4Ns Local area networks. 2.3 Applications Some applications that could be supported by B-ISDN connectionless data service are: a) b) interconnection of LANs; c) distributed processing: d) high speed file transfer with low latency; multi-site
17、interactive computer aided design (CAD). 3 Procedures 3.1 Provisiodwithdrawal 3.1.1 By arrangement with the Administration. 3.1.2 Nom1 procedures The service may be provided directly accessed by high speed end systems or by means of gateways using permanent, semi-permanent or switched connections be
18、tween the subscribers premises and the connectionless service node. , 2 Recommendation F.812 (081p2) 3.2 Normal procedures 3.2.1 Activation/deactivation/registratwn Upon request from the user, the service provider provides aii necessary functions for enabling end-to-end transmission. 3.2.2 Invocatio
19、n and operation In normal operation the user sends data without establishing, releasing or maintaining a connection. All information which is required to route the data from the source to the destination is contained in the connectionless CL-PDU (ee Q 2.2.4). 3.3 3 -4 3.5 3.6 3.6.1 Exceptional proce
20、dures Not applicable. Altenate procedures Not applicable. Validation Each CL-PDU includes a source address validated by the network. Quality of service General This section covers user oriented aspects of quality of service (QOS) speciftc to the broadband connectionless data bearer service. Overall
21、principles for QOS for B-ISDN are contained in Recommendation 1.350. User oriented QS issues are focused on end-to-end perceivable effects and not on their causes within the network. Parameters for user QS could be measured at the UNI. 3.6.2 Categories of user defined QOS 3.6.2.1 Lost PDU ratio This
22、 parameter defines the ratio of total number of PDUs sent by the originator and not delivered at the destination UNI to the total number of PDUs sent. Total PDUs not delivered = lost PDU Total PDUs sent 3.6.2.2 Maximum transfer delay This parameter defines the maximum PDU transfer delay between the
23、source UNI and the destination UNI. If the transfer of a PDU exceeds the time iimit, the PDU is assumed lost to the user. This time delay includes, in a B-ISDN environment, the sum of the cell delays per switch and per transmission system, and the PDU disassembly and reassembly at the source and des
24、tination nodes. 3.6.2.3 PDU, integrity This parameter defines the frequency of corrupted and/or duplicated PDUs. Recommendation F.812 (O/92) 3 CCITT RECMN*F.8 - Address Screening. ANNEX A (to Recommendation F.8 12) Broadband connectionless data bearer service category Sub-categories Bearer service a
25、ttributes Information transferred attributes 1 Information transfer mode 1.1 Connection mode 1.2 Traffic type 1.3 Timing end-to-end 2 Information transfer rate (bit/s) 2.1 Peak bit rate 2.2 Mean bit rate 3 Information transfer capability 4 Structure 4.1 Maximum CL-PDU size 5 Establishment of communi
26、cation (ATM access connection) D Value of attributes PDU (Note 1) Connectionless (CL) Variable bit rate (VBR) Not required (Note 2) (Note 2) unrestricted Protocol data unit integrity (Note 3) Demand, reserved, permanent 4 Recommendation F.812 (OW2) CCITT RECHN*FmBL2 92 4Bb259L 0575785 562 Sub-catego
27、ries Bearer service attributes Information transferred attributes (cont.) 6 Symmetry 7 Communication configuration Access attributes 8 8.1 User information Access channel and rate (biffs) 8.2 Signalling 9 Access protocols 9.1 Signalling access protocol - Physical layer 9.2 Signalling access protocol
28、 - ATM layer 9.3 Signalling access protocol - ATM adaptation layer AAL 9.4 Signalling access protocol layer 3 (above AAL) (Here “layer 3” corresponds to signalling terminology, not B-ISDN PRM.) 9.5 Information access protocol - Physical layer 9.6 Information access protocol - ATM layer 9.7 Informati
29、on access protocol - ATM adaptation layer AAL 9.8 Information access protocols - Layers above AAL General attributes 10 Supplementary services provided 11 Quality of Service D Value of attributes Unidirectional Point-to-point, multicast The medium service bit rate at 155.52 Mbitls, 622.08 Mbiffs int
30、erfaces is for further study (Note 2) Signalling virtual channel for signalling for ATM access connection Rec. 1.432 For establishment of switched connections between the B-ISDN subscriber and the CL service node. Connectionless protocols above the ATM adaptation layer are for further study Recs. 1.
31、150,1.361 Rec. 1.363, Rec. 1.432 Recs. 1.150,1.361 Recs. 1.362,1.363, type 4 (Note 3) (Note 3) Closed User Group Address Screening Lost PDU ratio Maximum transfer delay PDU integrity Recommendation F.812 (OW2) 5 CCITT RECMN*F=BLZ 92 D 4862593 057578b 4T9 D Sub-categories Bearer service attributes Ge
32、neral anribures (cont.) 12 Interworking possibilities 13 Operational and commercial aspects D Value of attributes With other CL services and data services Nore I - The PDU provides for the transfer of the service information. However, this is transported in the B-ISDN via the payload of the ATM cell
33、s. Note 2 - As described in Recommendations 1.432 and 1.211, the maximum service bit rate at the 155.52 Mbis interface will be less than 135.631 Mbils. The maximum bit rate at the 622.08 Mbis is for further study. The actual value depends on the capacity required by signalling, operation, administra
34、tion and maintenance (OAM), and ATM adaptation overheads (for further study). Also, granularity of the actual service bit rates offered by the network is contained in the appropriate I-Series Recommendations. Variable bit rate means that the peak bit rate as information transfer rate attribute value
35、 is not necessarily equal to the mean bit rate at the Sf reference point. Actual rate may be lower than peak bit rate. The characteristics are determined by the ATM connection. Nore 3 -Exact values for these attributes are contained in appropriate Q- and I-Series Recommendations. ANNEX B (to Recomme
36、ndation F.8 12) Alphabetical list of abbreviations used in this Recommendation AAL ATM B-ISDN CAD CL CL-PDU CO LAN PDU PRM ws UNI ATM adaptation layer Asynchronous transfer mode Broadband aspects of integrated services digitai network Computer aided design Connectionless Connectionless protocol data unit Connection oriented Local area network Protocol data unit Protocol reference model Quaiity of service User-network interface 6 Recommendation F.812 (OWZ)
