1、 ATIS-0300011 Next Generation Interconnection Interoperability (NGIIF) Reference Document Part III, Installation and Maintenance Responsibilities for SS7 Links and Trunks Version 12.0 ATIS is the leading technical planning and standards development organization committed to the rapid development of
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5、on Commission (CITEL). ATIS is accredited by the American National Standards Institute (ANSI). For more information, please visit www.atis.org. Notice This document was developed by the Alliance for Telecommunications Industry Solutions (ATIS) sponsored Next Generation Interconnection Interoperabili
6、ty Forum (NGIIF). The NGIIF addresses next-generation network interconnection and interoperability issues associated with emerging technologies. Specifically, it develops operational procedures which involve the network aspects of architecture, disaster preparedness, installation, maintenance, manag
7、ement, reliability, routing, security, and testing between network operators. In addition, the NGIIF addresses issues which impact the interconnection of existing and next generation networks and facilitate the transition to emerging technologies. All changes to this document shall be made through t
8、he NGIIF issue resolution process Note Regarding Previous Versions The NIIF Reference Document was formerly known as the Network Operations Forum (NOF) Reference Document. The NOF Reference Document was published and maintained by Bellcore. The last version of the NOF Reference Document is Issue 13.
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13、erly NIIF 5018 The NGIIF Reference Document, Part III, Installation and Maintenance Responsibilities for SS7 Links and Trunks is an ATIS standard developed by the NGIIF Published by Alliance for Telecommunications Industry Solutions 1200 G Street, NW, Suite 500 Washington, DC 20005 Copyright 2011 by
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15、 . Printed in the United States of America. 3 INSTALLATION, TESTING The architecture with ASP STPs connected to ASC STPs (Figure 1) requires three-way physical diversity of CCS link facilities. The architecture with ASP STPs connected to ASC SPs (Figure 2) requires two-way physical diversity of CCS
16、link facilities. Three-way physical diversity between ASP STPs and ASC STPs means that no two failures should simultaneously disable all three physical diverse link sets1between ASP STPs and ASC STPs (see Ex. Figure 1). _ 1A (signaling) link set is a set of signaling links directly connecting two si
17、gnaling nodes. 9 Two-way physical diversity between ASP STPs and ASC SPs means that no single failure should simultaneously disable both two physically diverse link sets between ASP STPs and ASC SPs (see Ex. Figure 2). Figure 1 - STP to STP Interface (Example) STP LINK CONFIGULATION B LINKS C LINKS
18、D LINKS Figure 2 - STP to SP Interface (Example) In general, n-way diversity between two portions of a network connected by multiple link sets means that no instance of (n-l) or less simultaneous failures will cause there to be no available link set between the two portions. ASPCCCBDDASCBDASPASC SPD
19、iversit y Considerat ionsNet wor k Access-STP Processor-A-Link Interface-A-Link TransportSTPASPSTPASC10 To avoid common cause failures (i.e., single failures that disable more than one link set), ideally link sets should not share common resources (e.g., electronic equipment), and wherever possible,
20、 should be physically separated. 2.6.1 Other Considerations CCS/SS7 route diversity, which assumes a network architecture that encompasses interconnecting mated STPs, is defined as signaling link sets that are on physically and electrically separate routes; exceptions to this guideline may apply to
21、building entrances, circuit distribution frames, power plants and some remote signaling points. 2.6.2 A-Link Concentrators for Local Service Providers (LSPs) LSCs/LSPs using A-Link Concentrators (ALCs) in their network are strongly encouraged to employ the mated pair architecture. If the LSCs/LSPs e
22、lect to use other architectures (Stand-Alone or Dual Access) and full point code routing (non-cluster routing) is utilized, the maximum number of subtending SPs should be negotiated between the operator of the ALC and the operator of the STP to minimize network management messages. 2.6.3 CCS Link In
23、terconnectivity Physical Link diversity is achieved first in the provisioning process and then maintained by operational procedures. When SS7 link facilities are leased it is the responsibility of both the user and the provider(s) to validate diversity. For example, if hypothetical company X leases
24、SS7 link facilities from separate companies Y and Z, company X may assume the facilities, for the SS7 links, to be diverse per NGIIF recommendations. However, company Z may also lease facilities from company Y, possibly resulting in company Xs SS7 link facilities not meeting NGIIF diversity validati
25、on recommendations. 2.6.4 Provisioning The provisioning process should take into account facility routing and equipment assignments such as: Cable routing Separate Equipment Powering and Fusing Building Entrance locations Distribution Frames Equipment Cable Racks Nailed Up Connections, e.g. Digital
26、Cross Connect Equipment 2.6.5 Maintenance In order to maintain link diversity, operational procedures should address the following link set maintenance considerations; Notification of ASC and ASP Centers. Determination of the status of all links in the combined link set. Expeditious return of the re
27、paired/operational link to service. Once diversity is designed into a combined link set, the ASC/ASP should ensure that the diversity is maintained: Diversity on all link sets should be routinely confirmed following the procedures described in the Link Diversity Validation Guidelines document, Part
28、III (Attachment G). Whenever maintenance or circuit order activity occurs on a link, or a failed link is restored, diversity on the combined link set should be confirmed following the procedures described in the Link Diversity Validation Guidelines document, Part III (Attachment G). At a minimum, va
29、lidation of diversity on all interconnected links in all link sets should be performed at least once every six (6) months following the procedures described in the Link Diversity Validation 11 Guidelines document, Part III (Attachment G). 2.7 Catastrophic SS7 Network Failures Each ASP/ASC is respons
30、ible for providing a point of contact. Contact numbers should be non toll free numbers and associated with the organization responsible for handling SS7 Catastrophic Network Failure reports. A contact list for SS7 Catastrophic failures is available in the NGIIF Service Provider Contact Directory. 3
31、LINK INSTALLATION During the installation period, all inquiries will be referenced by the ASP Service Order number and circuit identification. 3.1 Signaling Point of Interconnection (SPOI) Signaling Point of Interconnection is a physical location on SS7 links, where the ASP and ASC exchange SS7 mess
32、ages. The SPOI location may be provisioned at the POT for testing of links with a theoretical point of physical demarcation, be co-located with a POT, or remotely located from present POT locations. Diversity requirements for Signaling Links should be considered in developing SPOI locations. 3.2 Pre
33、-service Testing Each company is responsible for that portion of the overall SS7 link(s) circuit they are providing. Each company must ensure that their link segments have been installed correctly, prior to cooperative acceptance testing. 3.3 Acceptance Tests For SS7 Link Circuits Link circuits that
34、 are being installed, as a facility should first be tested at Level 1. The recommended tests for DS-1 acceptance testing is documented in, PART IX, Section 5F; Acceptance of DS-1. When such testing meets the parameters for acceptance of the DS-1 facility, the recommended tests to ensure compatibilit
35、y of the DS-1 to pass MTP Levels 2 MTP Compatibility Tests, (Levels 2 $ 3) 3.4 ASP Prove In Period A prove in period, not to exceed seven (7) days is recommended, subject to the bilateral agreement of the Service Providers. The 24 hour SP to SP Acceptance limits should not be exceeded in any 24 hour
36、 interval during the prove in period. 3.5 Synchronization Improper synchronization can result in circuit impairments which should be investigated and synchronization problems corrected. Problems that cannot be resolved, should be referred to your Synchronization Coordinator. 12 Companies Synchroniza
37、tion Coordinators are listed in the NGIIF Service Provider Contact Directory, which is available from the NGIIF. If the ASC/ASP has its own primary frequency standard that meets the CCITT standard for national networks (G.811, G.822), synchronization of the digital SS7 link(s) will be by the plesioc
38、hronous method of operation. If either network does not conform to the CCITT standard, the non-conforming company will use loop timing to accept SS7 link(s) timing from the conforming company. When the link interface is a DSOA interface, the interface must be plesiochronous or timed to the same sour
39、ce as the facility. 3.6 Compatibility Testing 3.6.1 SS7 Inter-Network Testing SS7 Inter-Network trunk signalling testing is a pre-cutover requirement. The following tests, MTP, ISUP and SCCP compatibility tests, are recommended to verify the compatibility of networks during interconnection. These te
40、sts are intended to be used as a recommended set of minimum tests of the SS7 protocol. It is assumed that the two (2) interconnecting networks may have some additional tests they may wish to perform during interconnection. In this case, these tests should be part of the bilateral agreements develope
41、d for SS7 network interconnections. Network compatibility testing verifies the correct interworking of two SS7 implementations. The tests are written for the interconnection of two given implementations. The full test suite of all recommended tests should be run between the two interconnecting compa
42、nies for any interconnection configuration that was not previously tested. Both the manufacturer model and software load of the interconnecting signaling network elements defines the interconnection configuration. Subsequent interconnections, using configurations previously tested by the two interco
43、nnecting companies, may be tested at their discretion. The tests in this document have been divided into Intrusive Tests and Non-Intrusive Tests and defined as follows: Intrusive Tests - The interconnecting circuit shall be interrupted, with the testing unit inserted into the circuit and acting as a
44、n emulator to the signaling point under test. Non-Intrusive Tests - The test shall be able to observe traffic traversing the link(s) between the two (2) signaling points, in a monitor mode. 3.6.2 Message Transfer Part (MTP) Compatibility Tests - Part III (Attachment A) The minimum set of MTP level 1
45、,2, and 3, protocol compatibility tests are required for switches between interconnecting (ASP/ASC) networks in support of SS7 link interconnection. 3.6.3 ISDN User Part (ISUP) Compatibility Tests Part III (Attachment B) The minimum set of ISUP protocol compatibility tests are required for switches
46、between interconnecting (ASP/ASC) networks implementing ISUP trunk interconnection. Signaling Connection Control Part (SCCP) Compatibility Tests-Part III (Attachment C) The minimum set of SCCP tests are required for switches between interconnecting (ASP/ASC) networks implementing Toll Free Database
47、and LIDB interconnecting services. Prior to the initiation of any testing, bilateral agreements will need to be reached defining entries to the Gateway screening, routing and global title tables required to support the testing. 13 3.7 Test Severity Analysis Criteria - Part III (Attachment D) The Tes
48、t Severity Analysis Criteria describes the potential impact of performing these compatibility tests on the network. 3.8 Completions After performance of the link(s) circuit acceptance tests and alignment of the link(s) by the SS7 protocol, the control office should report the order as completed. The
49、 acceptance of Level 1, 2, 3 tests would constitute a link in service. 3.9 Rearrangements The ASP or ASC will coordinate rearrangements not resulting in a change of operation or design. Removal from service, rearrangement timing and completion testing will be negotiated on an individual basis. Upon completion of the rearrangement, sufficient cooperative testing should be performed to ensure the proper operation of the service. 3.10 Timer Values ASC and ASPs need to exchange T2 timer settings prior to interconnection. 4 LINK MAINTENANCE The
