1、 ._ CCITT RECMN*E*L73 93 4862593 0560479 B INTERNATIONAL TELECOMMUNICATION UNION CCITT THE INTERNATIONAL TELEGRAPH AND TELEPHONE CONSULTATIVE COMMITTEE TELEPHONE NETWORK AND ISDN OP ERATI ON, NU M B ERING, ROUTING AND MOBILE SERVICE E.173 ROUTING PLAN FOR INTERCONNECTION BETWEEN PUBLIC LAND MOBILE N
2、ETWORKS AND FIXED TERMINAL NETWORKS Recommendation E.173 I Geneva, 1991 - CCITT RECMN*E.173 91 4862593 0560480 4 m INTERNATIONAL TELECOMMUNICATION UNION CCITT THE INTERNATIONAL TELEGRAPH AND TELEPHONE CONSULTATIVE COMMITTEE TELEPHONE NETWORK AND ISDN OPERATION, NUMBERING, ROUTING AND MOBILE SERVICE
3、E.173 ROUTING PLAN FOR INTERCONNECTION BETWEEN PUBLIC LAND MOBILE NETWORKS AND FIXED TERMINAL NETWORKS Recommendation E.173 i Geneva, 1991 CCITT RECMNrE.173 91 M 48b2591 0560481 b FOREWORD The CCIIT (the International Telegraph and Telephone Consultative Committee) is a permanent organ of the Intern
4、ational Telecommunication Union 0. CC 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 Plenary Assembly of CCT which meets every four years, establishes the topics for s
5、tudy and approves Recommendations prepared by its Study Groups, The approval of Recommendations by the members of CCIT between Plenary Assemblies is covered by the procedure laid down in CCITT Resolution No. 2 (Melbourne, 1988). Recommendation B.173 was prepared by Study Group II and was approved un
6、der the Resolution No. 2 procedure on the 23rd of August 1991. CcfIT NOTE In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication Administration and a recognized private operating agency. O ITU 1991 Ail rights reserved. No part of this pub
7、lication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without pemiission in writing from the ITU. CCITT RECMN*E*173 71 4862573 0560482 8 Recommendation E.173 R0“G PLAN FOR INTERCONNECTION BETWEEN PUBLIC LAND MOBILE NETWORK
8、S AND FIXED TERMINAL NETWORKS 1 introduction 1.1 between public land mobile networks (PLMN) and fixed terminal networks (e.g. PSTNDSDN and PSPDN). With the worldwide introduction of public land mobile service there exists a need for interconnection 1.2 This Recommendation covers the routing plan for
9、 interconnection between PLMN and the public switched telephone networkhntegrated services digital network (PSTNDSDN) and between PLMN and the public data networks (PDN). 1.3 It provides guidelines for routing when interconnecting PLh4N and fixed terminal networks, and indicates some basic rules for
10、 routing of cails between the networks. Routing between networks must adhere to regulatory conditions which exist within a given country or Administration. Bilateral agreements may be required to establish the actual interconnection arrangements between network operators. 1.4 This Recommendation cov
11、ers terrestrial-based PLMNs. Satellite-based PLMNs are for furher study. 1.5 Routing requirements within fixed terminal networks are described in the following Recommendations: E.171 International telephone routing plan; E.172 x.110 G. 173 (Draft) Transmission planning aspects of the speech service
12、in digital public land mobile networks. Call routing in the ISDN era; International routing principles and routing plan for public data networks; 2 Terminology CSPDN Circuit swiched public data network DCME Digital circuit multiplexing equipment DSI Digital speech interpolation DTE Data terminal equ
13、ipment FDTE IDSE International data switching exchange Fixed data terminal equipment, e.g. a DTE connected to the (PDN) ISC International switching centre ISDN Integrated services digital network (within this Recommendation ISDN means the circuit switched part of the network; for the packet switched
14、 part see PDN) LMDTE Land mobile data terminal equipment, e.g. a DTE connected to PLMN LMS Land mobile station LRE Low rate encoding MSC Mobile switching centre (this is a centre that handles mobile traffic) Recommendation EA73 1 CCITT RECMNxE.173 91 = 48b2591 0560483 T W PDN Public data network, e.
15、g. CSPDN, PSPDN or PHPDN in ISDN PHPDN Packet handler public data network PLMN Public land mobile network PSPDN Packet switched public data network PSTN Public switched telephone network QOS Quality of service TAS1 Time assignment speech interpolation TE Terminal equipment 3 Scope 3.1 This Recommend
16、ation includes the routing of calls between users of PLMN and the users of PSTNDSDN or PDN. The term “call” encompasses all types of user-to-user communication, e.g. normal speech calls, data calls, text messages and emergency caiis. 3.2 The following interconnection cases are considered PLMN e- PST
17、NDSDN (se Note 1) PLMN e- PSTNDSDN e PLMN (see Note 1) PLMN PDN (SW Note 2) PLMN PDN PLMN (SW Note 2) PLMN PSTNDSDN PDN (SW Note 2) PLMN e PSTNLSDN e PDN e- PSTNDSDN e- PLMN (see Note 2) Note I - The abbreviation PSTNDSDN means one or more networks of the same type in series. Note 2 - The abbreviati
18、on PDN means one or more networks of the same type in series. 3.3 A PLMN may be configured either as an extension of PSTNLSDN or as an integral part of PSTNLSDN. This Recommendation deals only with the first case. When PLMN and PSTNDSDN are integrated, the routing of calls shall follow the routing R
19、ecommendations E.171 for the PSTN and E.172 for the ISDN era. 4 Network structure The network structure shows the last choice routes, e.g. normally the route with the highest number of circuits in tandem. The last choice route will be determined by the type of traffic (e.g. speech versus packet data
20、) and the location of the originating and terminating terminals. 4.1 Between PLMN and PSTN/SDN To minimize the administrative and operational burden on international switching centres (ISC), the interconnection between PLMN and PSTNDSDN should take place nationally. The network structure for the tra
21、ffic between PLMN and PSTNASDN is shown in Figure 1E.173. It indicates the last choice route between two mobile stations in different countries. 2 Recommendation E.173 CCITT RECMN*E*173 91 4862571 0560484 L M Country 1 Counby 2 -1920-90 pI(IuRE 1m.173 Nehrorksiructureforthetrsmc between PLMN and PS“
22、N/ISDN 4.2 Between PLMN and PDN 4.2.1 To minimize the administrative and operational burden on international data switching exchanges (IDSE) the interconnection between PLMN and PDN should take place nationally, either directly between PLMN and PDN or indirectly via PSTNLSDN. The method for intercon
23、nection is a national matter. 4.2.2 The last choice route between two LMDTEs or between LMDTE and a FDTE in PDN in two different countries will depend upon how the interconnection between PLMN and PDN is implemented. The network structure for the rraffic between PLMN and PDN is shown in Figure 2B.17
24、3. I Country 1 Country 2 T2193-90 Note - The method for interconnection of PLMN and PDN is a national matter. FIGURE 2m.173 Network structure Por the traffic between PLMN and PDN Recommendation E.173 3 - - - - - CCITT RECMN*E*173 71 4862571 0560485 3 5 Maximum number of circuits in tandem Recommenda
25、tion E.172 gives the maximum allocation for the number of nodes and links in the national and international part of PSTNfiSDN for call routing in the ISDN era, and Recommendation X.110 gives the maximum allocation of links in tandem in the international part of PDN for call routing within PDN. 5.1 V
26、ia PSTN/SDN 5.1.1 The maximum number of circuits in tandem will be on an international call between two land mobile stations, that follows the last choice route indicated in Figure 1E.173. The last choice route is composed of two national and one international element as shown in Figure 3B.173. Each
27、 national element consists of a PLMN part and a PSTNDSDN part. The international element consists only of PSTNfiSDN. International element I element PLMN PSTNIISDN PLMN 4 LA LA w D, T224-91 FIGURE 3m.173 Elements of an international call between land mobile stations 5.1.2 With more than two national
28、 elements in series the planning of national networks and interconnection between PLMN and PSTN/ISDN may be significantly affected, due to the fact that the maximum number of circuits in tandem should not be exceeded. Therefore, placing more than two national elements in the last choice route betwee
29、n two land mobile stations in different countries should be avoided. 5.1.3 Table 1E.173 shows the maximum allocation of nodes and links in the national element when interconnecting PLMN and PSTNDSDN. The maximum number of nodes and links are taken from the national node and link allocation in Recomm
30、endations E.172 and G.801. The maximum number of nodes and links in the international element is given in Recommendation E.171. 5.2 Via PDN 5.2.1 The maximum number of circuits in tandem will be on an international call between two LMDTEs in different countries. Normally the host computer will be a
31、FDTE connected to PDN, but the limiting case will be between LMDTEs in two different countries as shown in Figure 4E.173. The nationd element on each side consists of the interconnection between the different networks. The international element consists of one or more PDNs. 4 Recommendation E.173 CC
32、ITT RECMN*E.173 91 4862591 O560486 5 TABLE 1lE.173 Maximum ailocation of nodes and links National element Links ?(Note) I Nodes I 4 O 1 3 Note - The interconnecting link between PSTNRSDN and PLMN belongs to the PSTNRSDN. National element I International element National I element ?ST? ISDN PLMN PDN
33、PSTN/ ISDN PLMN L1 rv rv rv PF b L1 T?Q2470-91 FIGURE 4m.173 Elements of an international data call between two land mobile data terminal equipments 5.2.2 The maximum number of nodes and links in the national element is a national matter, however the Quality of Service (QOS) parameters (e.g. congest
34、ion, call setup time, data transfer delay) must be considered when sructuring the interconnection between PLMN and PDN. For the PDN part of the connection, the QOS parameters are given in Recommendations X.130, X.131, X.135, X.136 and X.137. The maximum number of nodes and links in the international
35、 element is given in Recommendation X.110. 5.2.3 (see 0 5.1.2). More than two national elements in the last choice route between two LMDTEs should be avoided 6 Services The impact of services on routing is for further study. Recommendation E.173 5 CCITT RECMN*E*173 71 4862571 0560487 7 7 Number of s
36、atellites and quality of service The use of satellites does not have influence upon the maximum number of nodes and iirsAxs given in 0 5.1.2 and 5.2.2. A satellite together with its up-link and down-link is, from a routing point of view, considered as a single link (satellite link). 7.1 PLMN speech/
37、audio calls 7.1.1 Speech and audio calls cover the voice and voice-band data service in PSTN and the speech and 3.1 kHz audio service in ISDN. Recommendation E.171 states that the speechlaudio calls in PSTNfiSDN may use only one satellite link, and that the inclusion of two or more satellite links i
38、n the same connection should be avoided where possible. The satellite link may be part of the national or international element. 7.1.2 Use of satellites in a call between two land mobile stations or between a land mobile station and a subscriber connected to the fsed network, may result in conversat
39、ional difficulties due to delay. Network planners should take this into account when implementing digital PLMNs. 7.1.3 Use of DCME (digital circuit multiplexing equipment), TAS1 (time assignment speech interpolation), DSI (digital speech interpolation) and LRE (low rate encoding) equipment may resul
40、t in degradation of service quality. Further study is required. 7.1.4 cal between two land mobile stations. Table 2E.173 shows the recommended maximum number of satellite links in an international voice/speech 6 Note -The use of PLMN in the international element assumes that PLMNs in different count
41、ries may be interconnected. Recommendation E.173 CCITT RECMN*E-173 91 4862591 0560488 9 9 7.2 PMN data calls 7.2.1 Data calls are calls between DTEs irrespective of the mode of operation (circuit or packet mode). 7.2.2 included, and the international element of the connection should normally not inc
42、lude more than two sateliite links. Recommendation X.110 states that for calis within PDN no more than three satellite links should normaily be 7.2.3 The use of national or international satellite links for caiis between DTEs in PLMN or between PLMN and PDN, may degrade the quality to such an extent
43、 that it becomes unsuitable for some ata services. Network planners should take this into account when implementing digitai PLMNs. 7.2.4 between two LMDEs in different countries, Table 3E.173 shows the maximum number of satelite links in the different elements of an international cail - TABLE 3B.173
44、 Recommended maximum number of sateiiite links for data calls I National element I O O 1 (Note 1) 1 (Note 1) 1 (Note 1) 2 (Note 2) 2 (Note 2) International element I National element 2 1 2 1 O 1 O 1 (Note 1) 2 (Note 2) O 1 (Note 1) 2 (Note 2) O 1 (Note 1) Note 1 -The satellite link may be used in PL
45、MN or PSTNLSDN. Note 2 -The satellite links may be used in PLMN andor PSTNLSDN. 8 Path selection To ensure that the Quality of Service is maintained when interconnecting PLMN and other networks, a set of rules and guidelines for planning of such interconnections and for the routing of calls are prov
46、ided. 8.1 Between PLMN and PSTN/SDN 8.1.1 and PLMN, the routing of calls between PLMN and PSTNiSDN should be as shown in Figure 5B.173. To minimize the administrative and operational buren on the international switching centres in PSTNhSDN Recommendation E.173 7 CCITT RECMN*E*3?3 93 E 4862593 056048
47、9 O E HURE 5rn.173 Ren- der& between PLMN d PSTNDSDN 8.1.2 International calls generated in PSTNASDN and destined for PLMN in another country should remain in the fixed network (PSTNDSDN) for as long as possible. The connection from PSTNDSDN to PLMN should take place in the destination country. 8.1.
48、3 The international routing of caiis between PLMN and PSTNIISDN is independent of a possible PLMN-PLMN interconnection. 8.2 Between PLM“ via PSTN/SDN 8.2.1 Where national regulations permit direct interconnection between PLMNs in different countries, the network operators can establish bilateral agr
49、eements to interconnect their PLMNs. The traffic, technical, economical and administrative advantageddisadvantages should be considered before such an interconnection is proposed. 8.2.2 The routing of international speecldaudio caiis between two PLMNs which are interconnected should be as shown in Figure 6B.173. TMOl950-90 4- - + Possible routes Noie I -National regulatory conditions may resict direct interconnection between PLMNs. Nore 2 - 1 and 2 indicates the order of preference. when selecting mutes. 8 FIGURE 6E.173 Routing of calls bet
