1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T Q.50.2TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (12/2002) SERIES Q: SWITCHING AND SIGNALLING International automatic and semi-automatic working Signalling for circuit multiplication equipment Signalling between International Switching Centres (ISC)
2、and Digital Circuit Multiplication Equipment (DCME) including the control of compression/decompression over an IP networkITU-T Recommendation Q.50.2 ITU-T Q-SERIES RECOMMENDATIONS SWITCHING AND SIGNALLING SIGNALLING IN THE INTERNATIONAL MANUAL SERVICE Q.1Q.3 INTERNATIONAL AUTOMATIC AND SEMI-AUTOMATI
3、C WORKING Q.4Q.59 Basic Recommendations Q.4Q.9 Numbering plan and dialling procedures in the international service Q.10Q.11 Routing plan for international service Q.12Q.19 General Recommendations relative to signalling and switching systems (national or international) Q.20Q.34 Tones for use in natio
4、nal signalling systems Q.35Q.39 General characteristics for international telephone connections and circuits Q.40Q.47 Signalling for satellite systems Q.48Q.49 Signalling for circuit multiplication equipment Q.50Q.59 FUNCTIONS AND INFORMATION FLOWS FOR SERVICES IN THE ISDN Q.60Q.99 CLAUSES APPLICABL
5、E TO ITU-T STANDARD SYSTEMS Q.100Q.119 SPECIFICATIONS OF SIGNALLING SYSTEM No. 4 Q.120Q.139 SPECIFICATIONS OF SIGNALLING SYSTEM No. 5 Q.140Q.199 SPECIFICATIONS OF SIGNALLING SYSTEM No. 6 Q.250Q.309 SPECIFICATIONS OF SIGNALLING SYSTEM R1 Q.310Q.399 SPECIFICATIONS OF SIGNALLING SYSTEM R2 Q.400Q.499 DI
6、GITAL EXCHANGES Q.500Q.599 INTERWORKING OF SIGNALLING SYSTEMS Q.600Q.699 PUBLIC LAND MOBILE NETWORK Q.1000-Q.1099 SPECIFICATIONS OF SIGNALLING SYSTEM No. 7 Q.700Q.799 Q3 INTERFACE Q.800Q.849 DIGITAL SUBSCRIBER SIGNALLING SYSTEM No. 1 Q.850Q.999 INTERWORKING WITH SATELLITE MOBILE SYSTEMS Q.1100Q.1199
7、 INTELLIGENT NETWORK Q.1200Q.1699 SIGNALLING REQUIREMENTS AND PROTOCOLS FOR IMT-2000 Q.1700Q.1799 SPECIFICATIONS OF SIGNALLING RELATED TO BEARER INDEPENDENT CALL CONTROL (BICC) Q.1900Q.1999 BROADBAND ISDN Q.2000Q.2999 For further details, please refer to the list of ITU-T Recommendations. ITU-T Rec.
8、 Q.50.2 (12/2002) i ITU-T Recommendation Q.50.2 Signalling between International Switching Centres (ISC) and Digital Circuit Multiplication Equipment (DCME) including the control of compression/decompression over an IP network Summary This Recommendation describes a signalling interface between an I
9、nternational Switching Centre (ISC) and a Digital Circuit Multiplication Equipment (DCME) that has the additional (compared to ITU-T Rec. Q.50) capability to control the compression/decompression function of the DCME. This signalling interface provides for the call by call control of a DCME in real
10、time. The difference between this Recommendation and ITU-T Rec. Q.50.1 is that the DCME control protocol is supported over an IP network. Source ITU-T Recommendation Q.50.2 (2002) was prepared by ITU-T Study Group 11 (2001-2004) and approved under the WTSA Resolution 1 procedure on 29 December 2002.
11、 Keywords Compression/decompression, DCME, IP Networks. ii ITU-T Rec. Q.50.2 (12/2002) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ o
12、f 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 Assembly (WTSA), which meets every four years, establishes the topi
13、cs 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 WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prep
14、ared on a collaborative basis with ISO 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 PROPERTY RIGHTS ITU draws attention to the possibility that the pra
15、ctice 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 by ITU members or others outside of the Recommendation devel
16、opment 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 this may not represent the latest information and are theref
17、ore strongly urged to consult the TSB patent database. ITU 2003 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. Q.50.2 (12/2002) iii CONTENTS Page 1 Scope 1 2 References. 1 2.1 References 1 2.2 Bibli
18、ography. 2 3 Definitions 2 4 Abbreviations 2 5 Requirements 2 6 Conceptual model . 3 7 Network architecture 3 7.1 E1 and IP network-based interface. 3 7.2 International switching centre 4 7.3 Digital circuit multiplication equipment 4 8 Protocol. 4 8.1 Information elements 5 8.2 SDL. 5 Annex A Signa
19、lling interface 9 A.1 Detailed protocol description . 9 ITU-T Rec. Q.50.2 (12/2002) 1 ITU-T Recommendation Q.50.2 Signalling between International Switching Centres (ISC) and Digital Circuit Multiplication Equipment (DCME) including the control of compression/decompression over an IP Network 1 Scope
20、 This Recommendation describes a signalling interface between an International Switching Centre (ISC) and a Digital Circuit Multiplication Equipment (DCME) with a built-in device controller that allows a per call control of various functions in the DCME in real time. It is based on the interface des
21、cribed in ITU-T Rec. Q.50 1. In addition to the functions described in 1 that can be controlled by the switch, the compression/decompression function in the DCME can also be controlled over an IP network. The DCME is of type 2 (see ITU-T Rec. Q.50 1). This interface is supported in E1-networks. The
22、signalling interface defined in this Recommendation assumes a fixed relationship between the circuits of the ISC and the DCME. This signalling interface is supported over an IP network. While this Recommendation is intended for use on international networks, the information defined here may be used
23、within national networks. 2 References 2.1 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations an
24、d other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. T
25、he reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. 1 ITU-T Recommendation Q.50 (2001), Signalling between Circuit Multiplication Equipment (CME) and International Switching Centres (ISC). 2 ITU-T Recommendation Q.50.1 (2
26、001), Signalling between International Switching Centres (ISC) and Digital Circuit Multiplication Equipment (DCME) including the control of compression/decompression. 3 ITU-T Recommendation G.763 (1998), Digital circuit multiplication equipment using G.726 ADPCM and digital speech interpolation. 4 I
27、TU-T Recommendation G.767 (1998), Digital circuit multiplication equipment using 16 kbit/s LD-CELP, digital speech interpolation and facsimile demodulation/remodulation. 5 ITU-T Recommendation G.768 (2001), Digital circuit multiplication equipment using 8 kbit/s CS-ACELP. 6 ITU-T Recommendation G.70
28、4 (1998), Synchronous frame structures used at 1544, 6312, 2048, 8448 and 44 736 kbit/s hierarchical levels. 2 ITU-T Rec. Q.50.2 (12/2002) 2.2 Bibliography The documents listed in this clause provide informative background material for the reader and are not normative within this Recommendation. 7 I
29、EEE 802 (2001), IEEE Standard for Local and Metropolitan Area Networks: Overview and Architecture. 3 Definitions This Recommendation defines the following terms: 3.1 E1 facility: A transmission link operating at 2048 kbit/s, supporting 30 or 31 64 kbit/s channels. 3.2 external: A device is called ex
30、ternal, when it is located outside of the switch. 4 Abbreviations This Recommendation uses the following abbreviations: CCF Call Control Function DCME Digital Circuit Multiplication Equipment DCMECF DCME control function DCMESF DCME switching function ISC International Switching Centre IP Internet P
31、rotocol UDP User Datagram Protocol 5 Requirements The protocol used between the ISC and the DCME must include the control signals/messages for the control of the compression/decompression function in the DCME. The interface is supported over an IP network. ITU-T Rec. Q.50.2 (12/2002) 3 6 Conceptual
32、model Q.50.2_F6.1r2DCMESF DCMECFCCFISC DCMEFunctional planePhysical planer1IP Networkphysical connectionrelationship between communicating pairs of functional entitiesmappingrnFigure 6-1/Q.50.2 Conceptual methodology model A master slave relation exists between the DCME switching function (located i
33、n the switch) and the DCME control function (located in the DCME). 7 Network architecture 7.1 E1 and IP network-based interface The DCME has a physical interface according to ITU-T Rec. G.704 6 which allows the DCME to be inserted in an E1 transmission facility. The network architecture deals with w
34、here DCME equipment is located in the network. The control info is transmitted over an IP network. Q.50.2_F7.1Q.50.2ISCDCMEE1abIP NetworkQ.50.2a DCMESFb DCMECFFigure 7-1/Q.50.2 ISC-DCME interface in an IP-network 4 ITU-T Rec. Q.50.2 (12/2002) 7.2 International switching centre The ISC provides an E1
35、 circuit interface and a control interface. The ISC also provides the logic to decide on a per call basis the control info to be sent to the DCME. The control info is conveyed to the DCME over an IP network. Q.50.2_F7.2DCMESF DCMESFQ.50.2 Q.50.2Inter exchange signallingSignallingsystemCall control(R
36、outingBearerControletc)MaintenanceSignalling systemInter exchange signallingNOTE Communication between DCMESF and Call Control can either be direct or via the SignallingSystem ProcessFigure 7-2/Q.50.2 Process diagram 7.3 Digital circuit multiplication equipment The DCME provides an E1 circuit interf
37、ace and an IP Network-based control interface. The control info is transmitted over an IP network. The compression/decompression function can be enabled/disabled for each circuit individually. Q.50.2_F7.3DCMEfunctionsDCMECFE1Q.50.2Figure 7-3/Q.50.2 Digital circuit multiplication equipment 8 Protocol
38、 The DCME control protocol is transported using UDP, as shown in Figure 7-4. Any Port number in the Dynamic and/or Private range (49 152 through 65 535) may be used. Q.50.2 (DCME control protocol) UDP (User Datagram Protocol) IP (Internet Protocol) Figure 7-4/Q.50.2 Transport of the DCME control pro
39、tocol over IP ITU-T Rec. Q.50.2 (12/2002) 5 8.1 Information elements The information elements supported by this Recommendation are the same as in ITU-T Rec. Q.50 1 added by those contained in Table 1. Table 1/Q.50.2 Information elements for the control of compression/decompression Type of informatio
40、n element Notes Direction of the information element 1.1 compression/decompression not allowed Sent to inform the “outgoing“ DCME do not compress/ decompress the bit stream, when a 3.1 kHz/speech select/seizure was sent to the DCME ISC DCME 1.2 decompression/compression not allowed Sent to inform th
41、e “incoming“ DCME do not decompress/ compress the bit stream ISC DCME 8.2 SDL system DCMEcom signal same as in Q.50and Comprdecompr, Comprdecomprnaenable cd disable cd DCMEcomQ.50 (e.g., Voicerequest, Nonvoicerequest, Release) Comprdecompr ComprdecomprnaTo/From Call Control/Maintenance Q.50 (e.g., A
42、vailablevoice, AvailablenonvoiceOutofservice, Backinservice) To/From DCME function enable cd disable cd Q.50 (e.g., Failure) /*Comprdecompr: compression and decompression allowed Comprdecomprna: compression and decompression not allowed enable cd: enable compression and decompression function disabl
43、e cd: disable compression and decompression function */Figure 8-1/Q.50.2 System “DCME communication“ 6 ITU-T Rec. Q.50.2 (12/2002) Call Control/Maintenance DCME functionblock DCMEcom signals Q.50 v.r./cd v.r./cd n.a. cd n.a. DCMESF DCMECF see Figure 8.1 see Figure 8.1 see Figure 8.1see Figure 8.1 Q.
44、50v.r./cdv.r./cd n.a.cd n.a.Q.50/* v.r./cd: voice request with compression and decompression allowed (ISC outgoing CME) v.r./cd n.a.: voice request with compression and decompression not allowed (ISC outgoing CME)cd n.a.: compression and decompression not allowed (ISC incoming CME)Note: The “v.r.“ s
45、ignal is optional; see Q.50.*/Figure 8-2/Q.50.2 Block “DCMEcommunication“ ITU-T Rec. Q.50.2 (12/2002) 7 process DCMESF DCME req:= v.r. voice req. comprdecompr outg DCME communication with inc DCMEcomprdecomprna comprdecompr comprdecomprna v. r. cd v.r./cd v.r./cd n.a. cd n.a. non voice r. Q.50INITID
46、LE*) no change compared with ITU-T Rec. Q.50 SEIZED OUTG. SEIZED INC.SEIZED OUTG. SEIZED OUTG.*)*)*) *) SEIZED INC.SEIZED INC. Q50.2protocol elements voice request/comprdecompr voice request/comprdecompr n.a. comprdecompr n.a. Figure 8-3/Q.50.2 “Process DCMESF“ 8 ITU-T Rec. Q.50.2 (12/2002) process
47、DCMECF port status:= local seized v.r./cd cd n.a.enable cd v.r./cd n.a. failure INITIDLE*) no change compared with ITU-T Rec. Q.50 SEIZED INC.SEIZED OUTG. SEIZED OUTG.*) SEIZED INC.communicate with remote DCME port status:= local seizedcommunicate with remote DCME disable cdremote v.r.disable cdport
48、 status:= remote seizedcommunicate with remote DCME*) SEIZED OUTG. *) dcl port status := idle; /* v.r./cd: voice request (with compression and decompression)v.r./cd n.a.: voice request (with compression and decompression not allowed)remote v.r.: port related information from the remote DCMEenable cd
49、: enable the compression and decompression function disable cd: disable the compression and decompression function */Figure 8-4/Q.50.2 “Process DCMECF“ ITU-T Rec. Q.50.2 (12/2002) 9 Annex A Signalling interface A.1 Detailed protocol description A.1.1 Message format The DCME Control Message is sent over the IP interface to control DCME. Routing of the Control messages to a specific DCME will be performed by the ISC using facility tables. The DCME Control Message contains five oct
