1、INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU X.6 Amendment I (03/2000) SERIES X: DATA NETWORKS AND OPEN SYSTEM COM MU N I CATI ON S Public data networks - Services and facilities M u It i cast service d ef i n it ion Amendment 1: Frame relay PVC multica
2、st service definition ITU-T Recommendation X.6 - Amendment 1 (Formerly CCITT Recommendation) ITU-T X-SERIES RECOMMENDATIONS DATA NETWORKS AND OPEN SYSTEM COMMUNICATIONS PUBLIC DATA NETWORKS Services and facilities Interfaces Transmission, signalling and switching Network aspects Maintenance Administ
3、rative arrangements Model and notation Service definitions Connection-mode protocol specifications Connectionless-mode protocol specifications PICS profoms Protocol Identification Security Protocols Layer Managed Objects Conformance testing General Satellite data transmission systems IP-based networ
4、ks MESSAGE HANDLING SYSTEMS DIRECTORY OS1 NETWORKING AND SYSTEM ASPECTS Networking Efficiency Quality of service Naming, Addressing and Registration Abstract Syntax Notation One (ASN. I) Systems Management fiamework and architecture Management Communication Service and Protocol Structure of Manageme
5、nt Information Management functions and ODMA functions OPEN SYSTEMS INTERCONNECTION INTERWORKING BETWEEN NETWORKS OS1 MANAGEMENT SECURITY OS1 APPLICATIONS Commitment, Concurrency and Recovery Transaction processing Remote operations OPEN DISTRIBUTED PROCESSING X.1-X.19 X.20-X.49 X.50-X.89 X.90-X. 14
6、9 X.150-X.179 X. 180-X. 199 X.200-X.209 X.210-X.2 19 X.220-X.229 X.230-X.239 X.240-X.259 X.260-X.269 X.270-X.279 X.280-X.289 X.290-X.299 X.300-X.349 X.3 50-X.3 69 x.370-x.399 X.400-X.499 X.500-X.599 X.600-X.629 X.630-X.639 X.640-X.649 X.650-X.679 X.680-X.699 X.700-X.709 X.710-X.719 X.720-X.729 x.730
7、-x.799 X.800-X.849 X.850-X.859 X.860-X.879 X.880-X.899 X.900-X.999 For further details, please refir to the list of ITU-T Recommendations. ITU-T Recommendation X.6 Multicast service definition AMENDMENT 1 Frame relay PVC multicast service definition Summary This amendment describes the optional conf
8、igurations for Frame Relaying Bearer Service. These configurations are known as Frame Relay Multicast. The definition and description of these configurations are the basis for defining the network capabilities required for the support of multicast service in Frame Relay networks. Source Amendment 1
9、to ITU-T Recommendation X.6 was prepared by ITU-T Study Group 7 (1997-2000) and approved under the WTSC Resolution 1 procedure on 3 1 March 2000. FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunic
10、ation Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conferen
11、ce (WTSC), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSC Resolution 1. In some areas of information technology which
12、 fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with IS0 and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. INTELLECTUAL PROPER
13、TY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted
14、 by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that
15、 this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. O ITU 2001 All 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, w
16、ithout permission in writing from ITU. ITU-T Recommendation X.6 Multicast service definition AMENDMENT 1 Frame relay PVC multicast service defintion 1) Clause 1 Add the following as a new paragraph at the end of clause I: Annex A describes the multicast services applicable in Frame Relay networks. 2
17、) New Annex A Add the following as a new Annex A: ANNEX A Frame relay PVC multicast service definition A.l Introduction This annex describes optional multipoint configurations for the Frame Relaying Bearer Service. These configurations are known as Frame Relay Multicast. The definition and descripti
18、on of these configurations are the basis for defining the network capabilities required for the support of the service in an ISDN. ITU-T 1.233.1 describes the ISDN Frame Relaying Bearer Service. A.2 Definition e multicast services provide the capability for frame relay service suppliers to offer poi
19、nt to ultipoint frame delivery services. The services in this annex are connection-oriented. That is, * bfore a user of a multicast service is able to send or receive any multicast data, the user must first ablish a connection (permanent virtual connection) to the multicast server. A.3 General descr
20、iption This service description describes the fi-ame relay multicast services from the user perspective. It addresses only the case where the multicast service is provided on a permanent virtual connection (PVC) and is configured by network administration. Multicast services on switched virtual tion
21、s (SVC) are for further study. Dynamic modifications to the multicast service eral, a frame relay data unit is addressed to a specific destination. When the data unit arrives at tination, the address has been modified and is delivered with an address reflecting the senders return path. A multicast s
22、ervice may take advantage of this function and combine it with a copy function to allow a user to send a single message to multiple destinations. These destinations may reside on a single network or multiple networks. onfiguration by the user is also for further study. A.4 Definitions These terms ar
23、e provided as a tool for better understanding of this annex. A.4.1 active group: The subset of a Multicast Group which is currently operational. A.4.2 These values have only local significance. DLCI is defined in Annex NQ.922. A.4.3 management interface, namely the procedures in Annex NQ.933. A.4.4
24、Received by multiple destinations; it is a one-in, many-out service. A.4.5 A.4.6 A.4.7 A.4.8 of a single frame to multiple destinations. A.4.9 at a particular frame relay access interface. data link connection identifier (DLCI): It is the identifier of a frame relay connection. data link connection
25、management interface (DLCMI): The term used to identify the PVC frame relay multicast service: One in which a single data unit transmitted by a source is leaf A member of a one-way or two-way multicast group which receives multicast frames. multicast group ID: A set of members participating in a fra
26、me relay multicast service. member: A participant in a multicast group. multicast connection: A connection established for the purpose of facilitating the sending multicast DLCI (Mdlc): The DLCI assigned to designate a particular multicast connection A.4.1 O A.4.11 frames. A.4.12 A.4.13 A.4.14 one-w
27、ay: A type of multicast service. root: The member of a one-way or two-way multicast group which transmits multicast two-way: A type of multicast service. N-way: A type of multicast service. station: A fi-ame relay DTE. That is any machine (router, host, etc.,) that uses the services of a fi-ame rela
28、y network. In the context of this annex, station does not refer to those devices that are a part of the frame relay network itself. AS Multicast service model This is a general purpose model and is consistent with the model described in clause 4 of the main body of this Recommendation; frame relay s
29、pecifics are discussed in later sections of this annex. A.5.1 One-way multicast service This multicast service requires that the root have point-to-point frame relay connections established to all leaves in the multicast group. The root will also maintain a separate one-way multicast connection to t
30、he multicast server. With this configuration, the root sends multicast fiames via the one-way multicast connection identified by a one-way multicast DLCI (Mdlci). The multicast server will accept frames from the Mdlci and will send the fi-ame to each leaf member of the active multicast group. Frames
31、 delivered in this manner arrive as though they were transmitted on the individual point-to-point connections established between the root and leaves. That is the DLCI (address) in the received frame reflects the source of the message and will not retain the Mdlci (multicast address). For example, F
32、igure A. 1 shows the root, station A, with a single frame relay interface (station A may have other interfaces which are not shown here). The multicast group may be viewed logically as the group of PVCs by c, and d. The one-way multicast service will accept a frame on Mdlci fi-om Station A and trans
33、mit it to each destination designated by the active multicast group. As these frames traverse the network, they are treated no differently than other frames, and therefore arrive at the destination stations as though they had been transmitted on each of the separate PVCs fi-om Station A. Station B w
34、ill receive the frame on its connection t, Station C on its connection u and Station D on its connection v. This service is useful in applications where the stations are routers or bridges. The multicast frame will typically be used for obtaining or verifying the presence or identification of the mu
35、lticast group members. As defined, the Mdlci is a one-way DLCI. That is, frames are never sent from the network to the root on it. Frames transmitted on the Mdlci which arrive at Station B have no different characteristics from those frames sent from Station A on DLCI “b“. Frames from the one-way mu
36、lticast group members to Station A are transmitted on DLCIs It-v“ and arrive on DLCIs “b-d“ respectively. Station A may also exchange frames with a single member of the multicast group over one of the It is important to remember that multicast and unicast are separate services offered by the fiame r
37、elay network. Frames maintain time ordering within a service, not among services. For example, if, in Figure A.l, station A sends one frame on DLCI b and then another on the Mdlci. If the service provider merges unicast and multicast traffic to station B on DLCI t, the frames are not guaranteed to a
38、rrive at station B with the unicast frame first and the multicast frame second. Note that the one-way multicast model does not mandate that all PVCs registered to Station A participate. Conversely, any and all PVCs registered to Station A may participate regardless of their destination. That is, Sta
39、tion A may have many other PVCs that are not associated with the multicast group for the one-way multicast connection. Station A may also have several PVCs for the same destination station included in the multicast group without conflict. PVCs that are members of the multicast group and the Mdlci it
40、self are required to share the same physical frame relay interface. There is no conceptual limit to the number of one-way multicast connections allowed per interface. The number may be limited, however, by the ability to report multicast connections and PVC status via the Data Link Connection Manage
41、ment Interface (DLCMI) if it is in use. DLCIS “b-d“. A.5.2 Two-way multicast service The two-way multicast service provides for duplex transmissions. In one direction the data units are multicast, while in the other, they are concentrated. One participant in a two-way multicast cokection is defined
42、as the root; it functions to send the data units into the multicast server for lticasting. The rest of the participants are defined as the leaves. The following rules apply to the o-way multicast service. II Any data units sent by the root are transmitted to all leaves in the active multicast group.
43、 ata units sent by a leaf are transmitted to the root of the active multicast group, but not to the eaves. Figure A.2 depicts the two-way multicast service. Station A is the root and station B, C, and D are the leaf members of the multicast group. Each participant (both the root and leaves) has two-
44、way connections. The multicast service will accept a fkhe from Station A on the Mdlci, a, and transmit it to each of the leaf members of the active Leaves may return data to the root via the same DLCI. For example Station C will send frames to Station A on DLCI c and they will arrive on station As M
45、dlci, a. This service is useful in an environment where the root does not need to communicate individually with the leaves and where the number of leaf stations prohibits the establishment of individual PVCs between the root and each of the leaves. For example, when using SDLC or similar polled prot
46、ocols, there may be many terminals connected to a limited number of host ports. The host broadcasts to a group of terminals over a multi-drop line; only one terminal has permission to respond at a time. The two-way multicast service could be used to transparently replace multi-drop lines, between th
47、e host and terminals. lticast group. A 7 u TO732650-99 Figure A.lK.6 - One-way multicast TO732660-99 Figure A.2K.6 - Two-way multicast A53 N-way multicast service The third multicast service is n-way multicasting. All transmissions in this scheme are duplex and all are multicast. All members of the
48、multicast group are transmission peers. Any data sent on a n-way multicast connection is sent to every other member of the active multicast group. For example, Figure A.3 shows four stations participating in an n-way multicast exchange. The n-way multicast service will accept a frame on the Mdlci fr
49、om Station A and transmit it to each of the other members of the active multicast group (stations, By C and D). When the frames reach the destination stations, the DLCI will reflect the multicast connection which the station may use to address the multicast group. This type of multicast service is convenient for applications that require all participants to acquire the same data. One might envision this type of multicast for use with teleconferencing or routing update protocols. Figure A.3m.6 - N-way multicast A.6 Data transfer A.6.1 General All fiames transmitted on any multicast connect
