1、INTERNATIONAL TELECOMMUNICATION UNION ITU=T TELECOMM U N KATION STAN DAR DIZATION SECTOR OF ITU E.728 (03/98) SERIES E: OVERALL NETWORK OPERATION, TELEPHONE SERVICE, SERVICE OPERATION AND HUMAN FACTORS Quality of service, network management and traffic engineering - Traffic engineering - ISDN traffi
2、c engineering Grade-of-service parameters for B-ISDN signalling ITU-T Recommendation E.728 (Previously CCITT Recommendation) STD-ITU-T RECMN E-728-ENGL 1998 m 48b2591 0647091 429 m OPERATION, NUMBERING, ROUTING AND MOBILE SERVICES INTERNATIONAL OPERATION OPERATIONAL PROVISIONS RELATING TO CHARGING A
3、ND ACCOUNTING IN THE INTERNATIONAL TELEPHONE SERVICE UTILIZATION OF THE INTERNATIONAL TELEPHONE NETWORK FOR NON- TELEPHONY APPLICATIONS ISDN PROVISIONS CONCERNING USERS E.330-E.399 QUALITY OF SERVICE, NETWORK MANAGEMENT AND TRAFFIC ENGINEERING NETWORK MANAGEMENT TRAFFIC ENGINEERING Measurement and r
4、ecording of traffic Forecasting of traffic E.490-E.505 E. 506-E. 509 Determination of the number of circuits in manual operation E.510-ES19 I Determination of the number of circuits in automatic and semi-automatic operation E.520-E.539 Grade of service E.540-E.599 Definitions E.600-E.699 E.700-E.749
5、 Mobile network traffic engineering E.750-E.799 QUALITY OF TELECOMMUNICATION SERVICES : CONCEPTS, MODELS, OBJECTIVES AND DEPENDABILITY PLANNING ITU-T E-SERIES RECOMMENDATIONS OVERALL NETWORK OPERATION, TELEPHONE SERVICE, SERVICE OPERATION AND HUMAN FACTORS For further details, please refer to ITU-T
6、List of Recommendations STD-ITU-T RECMN E-728-ENGL 1998 = 4862591 Ob47092 365 ITU-T RECOMMENDATION E.728 GRADE-OF-SERVICE PARAMETERS FOR B-ISDN SIGNALLING Summary This Recommendation defines the grade-of-service parameters for B-ISDN signalling for the Network Node-Interface. It considers both link-
7、by-link and edge-to-edge B-ISDN protocol functions. Reference connections for these protocol functions are provided, and grade-of-service target values are given based on these reference connections. Source ITU-T Recommendation E.728 was prepared by ITU-T Study Group 2 ( 1997-2000) and was approved
8、under the WTSC Resolution No. 1 procedure on the 9th of March 1998. Recommendation E.728 (03/98) I - STD.ITU-T RECMN E.728-ENGL 1998 4862591 Ob47093 ZTL FOREWORD ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommuni- cations. The ITU Telecom
9、munication Standardization Sector (ITU-T) is a permanent organ of the ITU. The IT-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 Standardizat
10、ion Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, 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. I
11、n some areas of information technology which 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 reco
12、gnized operating agency. INTELLECTUAL PROPERTY RIGHTS The ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. The ITU takes no position concerning the evidence, validity or applicability of cl
13、aimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, the ITU had not received notice of intellectual property, protected by patents, which may be required to implement this
14、Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. O ITU 1998 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electroni
15、c or mechanical, including photocopying and microfilm, without permission in writing from the ITU. 11 Recommendation E.728 (03/98) 1 2 3 4 5 6 7 8 . STDSITU-T RECMN E-728-ENGL 1998 W 4862593 Ob47094 138 = CONTENTS Scope References Terms and Definitions Abbreviations . Overview of B-ISDN signalling .
16、 5.1 B-ISDN signalling protocols 5.2 B-ISDN signalling network architectures . Reference connections for B-ISDN signalling . 6.1 Reference connections for Link-By-Link signalling functions 6.2 Reference connections for Edge-to-Edge signalling functions . GOS parameters and target values . Recommenda
17、tion history Annex A . Explaining the basis for the GOS parameters in this Recommendation . Recommendation E.728 (03198) Page 1 1 1 1 2 . 111 STD=ITU-T RECMN E.728-ENGL 1998 W 4862591 Ob47095 074 Recommendation E.728 GRADE-OF-SERVICE PARAMETERS FOR B-ISDN SIGNALLING (Geneva, 1998) 1 Scope This Recom
18、mendation considers Broadband ISDN (B-ISDN) signalling for the Network-Node Interface (NM). It considers only fixed networks. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation.
19、At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references li
20、sted below. A list of the currently valid ITU-T Recommendations is regularly published. - - CCIT Recommendation E.723 (1992), Grade-ofservice parameters for Signalling System No. 7 networks, ITU-T Recommendation 4.701 (1993), Functional description of the Message Transfer Part (MP) Signalling System
21、 No. 7. ITU-T Recommendation Q.706 ( 1993), Message transfer part signalling performance. ITU-T Recommendation Q.766 (1 993), Performance objectives in the integrated services digital network application. - - - ITU-T Recommendation 4.2 100 ( 1994), B-ISDN Signalling ATM Adaptation Layer (SAAL) overv
22、iew description. ITU-T Recommendation 4.2761 (1995), Functional description of the B-ISDN User Part (B-ISUP) of Signalling System No. 7. - 3 Terms and Definitions The terms and definitions in this Recommendation are as applied in the above references. 4 Abbreviations This Recommendation uses the fol
23、lowing abbreviations: ANM ASE ATM B-ISDN B-ISUP ETE I GOS IAM LBL MTP N-ISUP Answer Message Application Service Element Asynchronous Transfer Mode Broadband Integrated Services Digital Network Broadband ISDN User Part Edge-to-Edge Grade-of-Service Initial Address Message Link-by -Link Message Transf
24、er Part Narrowband ISDN User Part Recommendation E.728 (03198) I STD-ITU-T RECMN E.728-ENGL II998 4862591 064709b TOO H NNI Network-Node Interface SAAL Signalling ATM Adaptation Layer SCCP Signalling Connection Control Part ss7 Signalling System No. 7 STP Signalling Transfer Point TCAP Transaction C
25、apability Application Part 5 Overview of B-ISDN Signalling 5.1 B-ISDN signalling protocols The B-ISDN “I signalling protocols (Q.276 1) support two distinct protocol functions: Link-by-link (LBL) protocol functions; and Edge-to-Edge (ETE) protocol functions. LBL protocol functions provide signalling
26、 capabilities for setting up and taking down end-to-end connections which require a virtual channel (which corresponds to a narrowband circuit). Broadband-ISDN User Part (B-ISUP) is the SS7 protocol part used by the LBL protocol functions, and it is a new user of the SS7 MTP Level 3. The signalling
27、message flow and signalling messages in B-ISUP are the same as for N-ISUP with the addition of an IAM Acknowledgment/ Reject message in B-ISUP. There is additional content in the B-ISUP messages to handle virtual channel and variable bandwidth characteristics. The network topology of the B-ISDN Netw
28、ork, as it relates to LBL protocol functions, is the same as for circuit-switched functions in the narrowband ISDN network. ETE protocol functions allow a signalling entity in the SS7 signalling network, in particular an origination or entry point in a network, to communicate with a destination sign
29、alling point in the destined network for transaction-type operations. ETE protocol functions are used to provide look-ahead capabilities such as allowing a network to check for called-terminal availability and compatibility, and to perform a negotiation (e.g., for bandwidth or quality) prior to virt
30、ual channel setup. The ETE protocol functions are provided using the existing SS7 TCAP and SCCP Class O basic connectionless service. 5.2 B-ISDN signalling network architectures B-ISDN NNI signalling protocol procedures are described in terms of six exchange types in the B-ISDN network: Originating
31、exchange (e.g., originating local end office); 0 Intermediate national exchange (e.g., toll switch); Outgoing international exchange (e.g., outgoing international switching center); 0 Intermediate international exchange (e.g., international transit switch); Incoming international exchange (e.g., inc
32、oming international switching center); Destination exchange (e.g. terminating local end office). The transport of signalling messages between these B-ISDN exchanges is assumed to be over signalling virtual channels on the broadband network. It would be possible to provide signalling transport over a
33、 narrowband SS7 network, but that is not viewed as a stable long-term architecture for B-ISDN signalling. A signalling link in the B-ISDN network is 2 Recommendation E.728 (03/98) - STD-ITU-T RECMN E.728-ENGL 399B = 4862593 Ob47097 9Y7 Number of STPs implemented with a Signalling ATM Adaptation Laye
34、r (SAAL) protocol stack (see Recommendation Q.2 100) on top of the ATM protocol layer at each end of the signalling link. As in narrowband SS7 signalling (Q.701), one can define three modes of signalling: associated mode, non-associated mode and quasi-associated mode. In associated mode the signalli
35、ng messages relating to a particular signalling relation between two signalling points are conveyed over a signalling link set interconnecting those signalling points. In non-associated mode the signalling messages relating to a particular signalling relation are conveyed over two or more link sets
36、in tandem passing through one or more signalling points, which are called Signalling Transfer Points (STPs), other than those that are the origin and destination of the messages. The quasi- associated mode is a special case of non-associated mode in which the path taken by a message is predetermined
37、. 1 9 2 6 The delay of signalling messages can be expected to be noticeably higher when signalling is done in the non-associated mode as compared with the associated mode. This is because in associated mode the messages travel end-to-end at the ATM level, but in non-associated mode the messages must
38、 go through the SAAL and MTP3 protocol layers at each STP, which will add noticeable time to the delays. Therefore, in defining reference connections and establishing GOS target values, the mode of signalling needs to be considered. In B-ISDN networks it is expected that the use of mixtures of assoc
39、iated and non-associated signalling will be frequent. 6 Reference connections for B-ISDN signalling The reference connections for LBL and ETE are intended to represent (near) worst-case situations; this means that GOS targets based on the reference connections should be satisfied in almost all pract
40、ical implementations. 6.1 Reference connections for Link-By-Link signalling functions Recommendation E.723 (Figure 1E.723) shows a number of example signalling paths for non-associated signalling between two exchanges. From these examples it is clear that the number of signalling links in the signal
41、ling path is the number of STPs plus 1 (with no STPs, the signalling mode is associated with one signalling link). Therefore, it follows that if a connection involves Ne, exchanges and NSTP STPs, the number of signalling links used for the end-to-end signalling is (N, + NSTP - 1). Therefore, referen
42、ce connections will be characterized by the number of exchanges and the number of STPs, and from that characterization the number of signalling links can be determined. Reference connections for LBL connections are contained in Table 1 for local, toll, and international connections. Both the number
43、of exchanges and the number of STPs for the different connection types are less than those found in Recommendation E.723. The number of exchanges is less because it is expected in B-ISDN that more direct connectivity will be possible. The number of STPs is less because more associated mode signallin
44、g is expected to be used in B-ISDN. It is also expected that as B-ISDN networks mature, the amount of associated mode signalling will increase. The number of STPs in the reference connections given in Table 1 represents expectations for the initial deployment of B-ISDN. As B-ISDN matures it is expec
45、ted that the number of STPs in a connection would decrease from what is in Table 1. Table UE.728 - Reference connections for B-ISDN LBL connections Connection type international 1 I Toll I Local I I Number of exchanges I 3 I 6 I 9 I 6.2 Reference connections for Edge-to-Edge signalling functions Ref
46、erence connections for ETE signalling functions are contained in Table 2 for local, toll and international transactions. For ETE transactions the transaction is between the two end points, but a network has an option of implementing screening functions at a network edge (gateway). Therefore, the ref
47、erence connections for ETE signalling are stated in terms of the number of STPs in the path and the number of gateway screening points. Recommendation E.728 (03198) 3 Table 2E.728 - Reference connections for B-ISDN ETE transactions Local Toll International Number of gateways Number of STPs 7 GOS par
48、ameters and target values O 2 4 1 3 5 The B-ISDN signalling GOS parameters for LBL connections are analogous to those defined in Recommendation E.723 for N-ISDN circuit-switched services, namely Initial Address Message (IAM) and Answer Message (ANM) delay. The IAM delay for a B-ISDN connection is de
49、fined as the time interval from when the originating exchange B-ISW application receives a SETUP message for the connection until the destination exchange B-ISW application sends a SETUP indication for the connection to the access signalling system. The ANM delay for a B-ISDN connection is defined as the time interval from when the destination exchange B-ISUP application receives a CONNECT indication from the access signalling system until the B-ISW application at the originating exchange sends a CONNECT indication to the access signalling system. Message type L B L
