1、ITU-T RECMN*M*4LLO 96 4862573 Ob38000 573 INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU M.411 O MAINTENANCE COMMON CHANNEL SIGNALLING SYSTEMS (05/96) INTER-ADMINISTRATION AGREEMENTS ON COMMON CHANNEL SIGNALLING SYSTEM No, 7 ITU-T Recommendation M.411 O (
2、Previously “CCITT Recommendation“) ITU-T RECMN*M-LIIO 96 9 4862593 ObLBOO3 4OT = FOREWORD The ITU-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (rrv). The ITU-T is responsible for studying technical, operating and tariff questions and
3、issuing Recommen- dations on them with a view to standardizing telecornunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendation
4、s 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). -T Recommendation M.4110 was revised by lJ-T Study Group 4 (1993-1996) and was approved under the WTSC Resolution No. 1 procedure
5、 on the 12th of May 1996. 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 All rights reserved. No part of this publication may be reproduced or utilized in any form
6、or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. CONTENTS 1 Introduction 2 Common Channel Signalling System No . 7 . 3 Aspects of SS No . 7 requiring inter-Adminisiration agreement . 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10
7、3.11 3.12 Signalling links and signalling security arrangements Signalling network consideration for cross-border traffic Routing label assignment Reset of circuit and circuit group messages Use of the circuit continuity check procedure Choice of the time slot to be used within the primary order dig
8、ital path for the signalling link Mode of signalling Circuit Identification Code . Choice of tests to be performed Changing from one specification of the signalling system to another Use of MTP Routing Verification Tests (MRVT), SCCP Routing Verification Tests (SRVT), and Circuit Validation Tests (C
9、VT) Exchange of signalling system operational measurements . 4 References . Timing on inter-Administration agreements Page 1 2 2 2 4 4 4 4 4 5 5 5 5 5 5 5 6 Recommendation M.4110 (0996) i ITU-T RECMN*M-4LLO 96 = Y862593 Ob38003 282 ABSTRACT hovides the various technical aspects that need to be consi
10、dered when undertaking inter-administration agreements to establish Common Channel Signalling System No. 7. KEYWORDS Agreements; common channel signalling; maintenance; propagation delay; signalling security; Signalling System No. 7. ii Recommendation M.4110 (05/96) ITU-T RECMN*M*411O 96 = 4862591 O
11、b18004 119 Recommendation M.4110 INTER-ADMINISTRATION AGRFCEMENTS ON COMMON CHANNEL SIGNALLING SYSTEM No. 7 (Melbourne 1988 approved as M. 770; revised and renumbered in 1992; revised in 1996) 1 Introduction The bringing into service of new Signalling System No. 7 requires that a number of agreement
12、s be made in advance by the Administrations about the responsibilities involving the following issues: - Installation and maintenance Link Two inter-connecting Administrations are responsible for the portion of an CCSS No. 7 link, which they maintain. Both Administrations are also responsible for en
13、suring that its portion of the CCSS No. 7 link(s) are installed and functioning properly. In addition, the Administrations should work cooperatively to perform CCSS No. 7 protocol tests to ensure the ability of the interfaces to correctly transmit and respond to CCSS No. 7 messages being passed betw
14、een their networks. Trunk Conversion from in-band signalling to CCSS No. 7 cannot be accomplished without a thoroughly planned process. Two Administrations implementation team should meet to discuss and identify all of the steps necessary for a successful trunk conversion. The implementation team sh
15、ould include individuals from both Administrations. Each Administration should establish a Cutover Committee of its own to ensure a smooth conversion; the cutover committee consisting of permanent members from the ordering, provisioning, engineering, operations, and billing discipline. - Testing CCS
16、S No. 7 Inter-Network signalling testing should be a pre-cutover requirement. MTP, ISUP and SCCP compatibility tests), are recommended to verify the compatibility of networks during interconnection. These tests are intended to be used as a recommended set of minimum tests of the CCSS No. 7 protocol.
17、 CCSS No. 7 route diversity, which assumes a network architecture that encompasses intercon- necting STps, is defined as signalling link sets that are on physically and electrically separate routes. Interconnecting Administrations should discuss their routing and Gateway Screening of Network Managem
18、ent Messages between interconnecting STPs to ensure that all appropriate messages can be routed in the presence of route failures. In the remote event that a total CCSS No. 7 failure is experienced, some means of communication between personnel in interconnecting networks may be required. Two interc
19、onnecting Administrations should determine what emergency communications are already available and/or what alternative methods, if any, will be provided. - Diversity - Screening and translations - CCSS No. 7 security *) See Recommendations 4.704,4.781,4.782,4.784 and 4.785. Recommendation M.4110 (05
20、/96) 1 ITU-T RECMN*M*4LLO 96 48b2591 Ob18005 055 W - CCSS No. 7 Software Validation CCSS No. 7 Software Validation is essential to ensure that the software products perform according to “agreed upon” Administration product requirements and that all reasonable care has been taken to identify and corr
21、ect any anomalies that have the potential to negatively impact the operation of switclsignalling nodes. - Some additional issues also need to be considered and those are: 0 routing of circuits (cable, satellite, etc.); circuit designation; mode of operation (incoming, outgoing, both-way); 0 order of
22、 selection of both-way circuit. This Recommendation outlines the inter-Administration responsibilities for provisioning and maintaining of the Signalling System No. 7. It deals with the physical interconnecting trunks and link) as well as the software necessary to support the use of the link) to tra
23、nsport CCSS No. 7 messages between Administrations. It is limited to procedures relating to the installation and maintenance of the CCSS No. 7 trunks and link) and associated software used to interconnect and provide services between two Administrations. This Recommendation also explains the princip
24、al inter-Administration agreements which must be made in advance of opening service on a Signalling System No. 7, and is provided as guidance to those Administrations intending to operate such a service. 2 Common Channel Signalling System No. 7 Many of the aspects covered by this Recommendation rela
25、te to matters contained in the specifications of SS No. 7, as appearing in the Q.700-Series Recommendations I. Where appropriate, cross references to such Recommendations are given. Recommendations 4.701 2, 4.721 3, 4.767 13 and 4.750 I41 provide functional descriptions of the Message Transfer Part
26、(M”), Telephone User Part (IZTP), ISDN User Part (ISUP). and Operation and Maintenance Application Part (OMM), respectively. The Q.780-Series Recommendations 4 provide guidance on how to test SS No. 7 (levels 2,3 and 4). 3 Aspects of SS No. 7 requiring inter-Administration agreement 3.1 Signalling l
27、inks and signalling security arrangements Signals for a given group of speech circuits between two exchanges may be “associated” (routed on a signalling link between the two exchanges), or “non-associated” (routed on two or more signalling links in tandem, involving one or more signal-transfer point
28、s) or a mixture of both (see 3.1.2Q.701 2). Before entering into detailed discussions on the type of signalling security arrangements required, it is desirable that the terminal Administrations exchange information on the type and manufacturer of their international signalling point (exchange, signa
29、lling transfer point, or network database) and the options available within their existing software systems. This information will enable each Administration to have an overall view of available signalling security arrangements. It will avoid misunderstandings and thus enable rapid progress in estab
30、lishing detailed arrangements. Sub- sequently, agreement on the following matters will be required. 3.1.1 CCSS No. 7 Link Control a) Provides trained personnel. b) Designates a Control office(s) for the overall responsibility for CCSS No. 7 link(s). 2 Recommendation M.4110 (05/96) ITU-T RECMN*M.4110
31、 96 4462591 Ob18006 T91 Cooperates with the other Administration to ensure that the CCSS No. 7 link(s) are installed in accordance with the service request. Notifies the appropriate Administration service centre when the service due date is to be changed. Sectionaiizes troubles to determine if the t
32、rouble is located in its facility, interface, or application or if the trouble is in other Administration facility, interface, or application. Ensures that any manually initiated tests performed on the CCSS No. 7 link(s) or applications will not negatively affect the other Administration CCSS No. 7
33、network. Coordinates any changes to its translations which may require changes to other Administration translations. Cooperatively participates with the other Administration to further identify, isolate and clear troubles which cannot be sectionalized into each other portions of the link or applicat
34、ionsoftware. Accepts and refers trouble reports from the other Administration relating to CCSS No. 7 and the services being provided over the link(s). Provides the other Administration Notification of Maintenance Releases. Overall coordination of control responsibilities: i) tracking of orders; ii)
35、coordination of testing; iii) coordination of link specific maintenance releases; iv) refemal to appropriate groups for repair; v) establishing of interface agreements; vi) responsibility for trouble agreements; vii) link(s) surveillance. Maintains complete and accurate installation and repair recor
36、ds. Notifies the other Administration of due date jeopardy in a timely manner. Coordinates any changes to its translations which may require changes to the Administration networks translations. Maintains complete and accurate installation and repair records. Provides a trouble reporting number(s) th
37、at is readily accessible 24 hours, 7 days a week. Some additional agreement on the following matters will be necessary for the reliability of CCSS No. 7 interconnection: i) ii) The use of “associated“ and/or “non-associated“ modes of signalling. The choice of Signalling Transfer Points (STPs) in the
38、 case where the “non-associated“ mode of signalling is used. iii) Security measures against signalling network link failure, e.g. the use of load sharing between link sets. If load sharing between link sets is to be used, agreement must be reached as to the number of link sets involved. iv) Alternat
39、ive routing within the signalling network in the event of failure of a link set, i.e. if load sharing is not used, which STPs are available for a given signalling network relation, and the order of selection of these. Due regard must be paid to the limitation of the number of STPs in tandem in a giv
40、en signalling network relation (see clause 514.705 5). The routing of the signalling network links must ensure that the propagation delay of the links is as low as possible, and not significantly higher than that of the speech circuits which are served by Signalling System No. 7. This is to minimize
41、 the initial speech clipping of the verbal answer from the called party. The above factors must also be considered in any restoration plans, although the non-availability of links may force Administrations to accept the possibility of clipping under failure conditions. v) Recommendation M.4110 (05/9
42、6) 3 ITU-T RECMN*M-YLLO 96 48b259L Ob18007 928 vi) The nature of the signalling network link to be used, e.g. 4.8 kbit/s analogue or 64 kbith digital, transmission routing, etc. vii) The method of error correction to be employed in a given signalling relation, i.e. basic or preventive cyclic retrans
43、mission (see clause YQ.703 6). viii) Emergency restart conditions. (If there is automatic allocation of signalling terminals or signalling data links at the end of a signalling link, it must be ensured that the value (“2) of the time-out is different at each end (see 7.3/Q.703 6 and 3.4.3/4.704 7).)
44、 ix) For security reasons, the separation of routing of signalling links has to be considered when selecting higher order paths. 3.2 Mode of signding Signalling System No. 7 provides for two basic modes of sending signalling information namely, “en bloc” or “overlap” (see Recommendation 4.724 8). 3.
45、3 Signailing network consideration for cross-border traffic For cross-border traflc between signalhg points, a bilateral agreement needs to be made for the routing label assignment of signalling point codes. Two alternative arrangements are described in clause 6/Q.705 5. One arrangement provides for
46、 signalling points which are handling cross-border traffk to be given signai point codes taken from the international numbering plan contained in Recommendation 4.708 9. The other provides for these signalling points to be identified by common national point codes. 3.4 Routing label assignment The r
47、outing label is that part of the message label which contains the information necessary to deliver the message to its destination point. It comprises the following (see 224.704 171): - Destination Point Code (DPC); - Originating Point Code (OK); - Signalling Link Selection (SLS) field or Signalling
48、Link Code (SLC). DFC and OPC labelling will be in accordance with Recommendation 4.708 9. However, it may be necessary to have a bilateral agreement for the SLS so that it can be assigned individually to signalling links. 3.5 Circuit Identification Code The Circuit Identification Code (CIC) indicate
49、s one speech circuit among those directly interconnecting the destination and the originating points. The allocation of CICs to individual circuits is determined by bilateral agreement and/or in accordance with predetermined rules. See 22314.723 lo. 3.6 Reset of circuit and circuit group messages In systems which maintain status in memory, there may be occasions when the memory contains errors. In such cases the circuits must be reset to the idle condition in both exchanges to make them available for new traffic. Since the exchange with the erroneo
