1、 International Telecommunication Union ITU-T Y.1413TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Corrigendum 1(10/2005) SERIES Y: GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS Internet protocol aspects Interworking TDM-MPLS network interworking User plan
2、e interworking Corrigendum 1 ITU-T Recommendation Y.1413 (2004) Corrigendum 1 ITU-T Y-SERIES RECOMMENDATIONS GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS GLOBAL INFORMATION INFRASTRUCTURE General Y.100Y.199 Services, applications and middleware Y.200Y.299
3、 Network aspects Y.300Y.399 Interfaces and protocols Y.400Y.499 Numbering, addressing and naming Y.500Y.599 Operation, administration and maintenance Y.600Y.699 Security Y.700Y.799 Performances Y.800Y.899 INTERNET PROTOCOL ASPECTS General Y.1000Y.1099 Services and applications Y.1100Y.1199 Architect
4、ure, access, network capabilities and resource management Y.1200Y.1299 Transport Y.1300Y.1399 Interworking Y.1400Y.1499 Quality of service and network performance Y.1500Y.1599 Signalling Y.1600Y.1699 Operation, administration and maintenance Y.1700Y.1799 Charging Y.1800Y.1899 NEXT GENERATION NETWORK
5、S Frameworks and functional architecture models Y.2000Y.2099 Quality of Service and performance Y.2100Y.2199 Service aspects: Service capabilities and service architecture Y.2200Y.2249 Service aspects: Interoperability of services and networks in NGN Y.2250Y.2299 Numbering, naming and addressing Y.2
6、300Y.2399 Network management Y.2400Y.2499 Network control architectures and protocols Y.2500Y.2599 Security Y.2700Y.2799 Generalized mobility Y.2800Y.2899 For further details, please refer to the list of ITU-T Recommendations. ITU-T Rec. Y.1413 (2004)/Cor.1 (10/2005) i ITU-T Recommendation Y.1413 TD
7、M-MPLS network interworking User plane interworking Corrigendum 1 Source Corrigendum 1 to ITU-T Recommendation Y.1413 (2004) was approved on 14 October 2005 by ITU-T Study Group 13 (2005-2008) under the ITU-T Recommendation A.8 procedure. ii ITU-T Rec. Y.1413 (2004)/Cor.1 (10/2005) FOREWORD The Inte
8、rnational 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 of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommend
9、ations 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 topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The appr
10、oval 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 prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administrat
11、ion“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g. interoperability or applicability) and compliance
12、 with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is req
13、uired of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice 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 Intelle
14、ctual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. Howev
15、er, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. ITU 2005 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. IT
16、U-T Rec. Y.1413 (2004)/Cor.1 (10/2005) iii CONTENTS Page 1) Summary. 1 2) Introduction 1 3) Clause 2 References. 1 4) Clause 3 Definitions 1 5) Clause 6 TDM-MPLS interworking 2 6) Clause 7.1 User plane requirements 3 7) Clause 8.1 Transport label . 4 8) Clause 8.3.3 Length field. 4 9) Clause 8.3.4.2
17、 Processing the sequence numbers 4 10) Clause 9.1 Structure-agnostic transport. 4 11) Clause 9.2 Structure-aware transport. 5 12) Clause 9.2.1 Structure-locked encapsulation. 5 13) Clause 10 Timing aspects 5 10 Timing aspects 5 14) Clause 11 Packet loss aspects 8 15) Clause I.1 Use of ITU-T Rec. Y.1
18、411. 8 16) Clause I.2 Use of AAL type 2 . 8 17) Appendix V Suggested common clock frequencies for RTP 9 18) Appendix VII Suggested number of AAL1 SAR PDUs per packet 9 ITU-T Rec. Y.1413 (2004)/Cor.1 (10/2005) 1 ITU-T Recommendation Y.1413 TDM-MPLS network interworking User plane interworking Corrige
19、ndum 1 1) Summary Replace: This Recommendation addresses required functions for network interworking between TDM networks up to DS3 or E3 rates and MPLS networks. With: This Recommendation addresses required functions for network interworking between TDM networks and MPLS networks whereby TDM up to
20、T3/E3 rates is transported over an MPLS network. 2) Introduction Replace the second sentence: Such interworking must ensure that TDM timing, signalling, voice quality, and alarm integrity be maintained. With: Such interworking must ensure that TDM timing, signalling, telephony voice quality, and ala
21、rm integrity be maintained. 3) Clause 2 References Replace: 32 ITU-T Recommendation P.562 (2004), Analysis and interpretation of INMD voice-service measurements. With: 32 ITU-T Recommendation P.800 (1996), Methods for subjective determination of transmission quality. Add the following new reference:
22、 35 ITU-T Recommendation G.811 (1997), Timing characteristics of primary reference clocks. 4) Clause 3 Definitions Replace: 3.2 structured TDM: TDM with any level of structure imposed by a FA (Frame Alignment Signal), such as that defined in 3, 4, 5, or 6. With: 3.2 structured TDM: TDM with any leve
23、l of structure imposed by an FAS (Frame Alignment Signal), such as that defined in 3, 4, 5, or 6. 2 ITU-T Rec. Y.1413 (2004)/Cor.1 (10/2005) Replace: 3.4 structure-agnostic transport: Transport of unstructured TDM, or of structured TDM when the structure is completely disregarded by the transport me
24、chanism. Structure-agnostic transport maintains the precise bit sequence of data and any structure overhead that may be present. The encapsulation provides no mechanisms for the location or utilization of a FA. With: 3.4 structure-agnostic transport: Transport of unstructured TDM, or of structured T
25、DM when the structure is completely disregarded by the transport mechanism. Structure-agnostic transport maintains the precise bit sequence of data and any structure overhead that may be present. The encapsulation provides no mechanisms for the location or utilization of an FAS. Add the following tw
26、o new definitions: 3.13 transport LSP: A label-switched path used for the transport of traffic between two IWFs. 3.14 interworking LSP: A label-switched path used for the transport of TDM traffic. Multiple interworking LSPs can coexist inside a single transport LSP. The interworking LSP is only sign
27、ificant to the IWFs, and is not used by forwarding devices in the MPLS network. 5) Clause 6 TDM-MPLS interworking Replace the first paragraph: The multi-protocol label switching (MPLS) technology 8 allows multiple services (such as IP, ATM, frame relay, and TDM) to be supported over a single network
28、ing infrastructure. With: Multi-protocol label switching (MPLS) technology 8 allows multiple services (such as Ethernet, IP, ATM, frame relay, and TDM) to be supported over a single networking infrastructure. Replace the second sentence in the third paragraph: For the TDM-to-MPLS direction, the cont
29、inuous TDM stream is segmented and encapsulated into an MPLS packet by the interworking function (IWF). With: For the TDM-to-MPLS direction, the continuous TDM stream is segmented and encapsulated into MPLS packets by the interworking function (IWF). ITU-T Rec. Y.1413 (2004)/Cor.1 (10/2005) 3 Replac
30、e: “circuit bundle“ in Figure 6-3 With: “TDM circuit“ as follows: 6) Clause 7.1 User plane requirements Replace: For transparent transfer of TDM in the user plane, the following capabilities are required: a) The ability to transport multiple TDM streams in an interworking LSP. b) Support for bidirec
31、tional connections with symmetric bandwidth and binding to the duplex TDM. c) The ability to transport the following unstructured TDM types: 1) T1 at 1544 kbit/s; 2) E1 at 2048 kbit/s; 3) T2 at 6312 kbit/s; With: For transparent transfer of TDM in the user plane, the following capabilities are requi
32、red: a) The ability to transport multiple TDM streams in a transport LSP. b) Support for bidirectional connections with symmetric bandwidth and binding to the duplex TDM. c) The ability to transport the following unstructured TDM types: 1) T1 at 1544 kbit/s as defined in ITU-T Rec. G.703 29; 2) E1 a
33、t 2048 kbit/s as defined in ITU-T Rec. G.703; 3) T2 at 6312 kbit/s as defined in ITU-T Rec. G.703; 4 ITU-T Rec. Y.1413 (2004)/Cor.1 (10/2005) 7) Clause 8.1 Transport label Replace the first sentence of the second paragraph: The 4-octet transport label identifies a LSP used to transport traffic betwe
34、en two IWFs. With: The 4-octet transport label identifies an LSP used to transport traffic between two IWFs. Replace the last sentence: The setting of the EXP and TTL fields of the transport label is outside the scope of this Recommendation. With: The setting of the EXP and TTL fields of the transpo
35、rt label is beyond the scope of this Recommendation. 8) Clause 8.3.3 Length field Replace: a) size of the Common interworking indicators; b) size of the optional timing information; and With: a) size of the Common interworking indicators (4 octets); b) size of the optional timing information (either
36、 0 or 12 octets, see 8.4); 9) Clause 8.3.4.2 Processing the sequence numbers Replace the last sentence of the first paragraph: The mechanism by which a packet is considered lost is implementation specific. With: The mechanism for detecting packet loss is implementation specific. 10) Clause 9.1 Struc
37、ture-agnostic transport Add the following new paragraph immediately before the note: Whenever a packet is lost, or received too late for playout, or is received with the L bit set, then the egress IWF shall generate the appropriate amount of AIS towards its TDM interface. Remove comma in the last li
38、ne of the note, i.e. replace: Examples where this may be beneficial are when interworking with ATM-based circuit emulation systems, or when SRTS-based clock recovery, is used. With: Examples where this may be beneficial are when interworking with ATM-based circuit emulation systems, or when SRTS-bas
39、ed clock recovery is used. ITU-T Rec. Y.1413 (2004)/Cor.1 (10/2005) 5 11) Clause 9.2 Structure-aware transport Replace: Structure-aware transport maintains correct operation of the remote TDM interface by removing structure overhead at ingress and regenerating it at egress, and preserves integrity o
40、f the TDM structure by structure-locking or structure indication. With: Structure-aware transport maintains correct operation of the remote TDM interface by regenerating FAS at egress, and preserves the integrity of the TDM structure by structure-locking or structure-indication. Whenever a packet is
41、 lost, or received too late for playout, or is received with the L bit set, then the egress IWF shall generate the appropriate amount of filler data in order to maintain TDM timing and FAS. While the insertion of arbitrary filler data may be sufficient to maintain the TDM timing, this may lead to re
42、duced perceived quality of telephony voice channels contained in the TDM. Depending on the expected percentage of packet loss, packet loss concealment mechanisms may need to be employed. 12) Clause 9.2.1 Structure-locked encapsulation Replace the last sentence of the third paragraph: If the packet p
43、ayload is comprised of M frames, the packetization latency will be M times 125 s. With: If the packet payload is comprised of M frames, the packetization latency will be M times 125 microseconds (s). In Figure 9-3, in the last row (box) under “padding“ Replace: (Note 2) With: (Note 3) 13) Clause 10
44、Timing aspects Replace all of clause 10 as follows: 10 Timing aspects TDM networks are synchronous and hierarchically distribute precise timing in order to maintain the required error performance. MPLS networks, not having been designed for TDM transport, have no inherent timing distribution mechani
45、sm, and so some other method of timing distribution must be provided. Four principal timing distribution scenarios may be identified, that differ in the availability and placement of timing sources. The selection of timing distribution mechanism may be made independently per TDM-MPLS interworking LS
46、P. 6 ITU-T Rec. Y.1413 (2004)/Cor.1 (10/2005) 10.1 Reference clock available at the TDM end systems Figure 10-1 depicts the scenario wherein the TDM end systems share a reference clock, distributed by means beyond the scope of this Recommendation. Alternatively, primary reference clocks 35 may be av
47、ailable at both sites and, due to their accuracy, the two clocks may be considered identical. Figure 10-1/Y.1413 Reference clock available at end systems In this scenario, each end system uses the reference clock to generate the timing used to transmit TDM data towards the IWF. The IWFs slave their
48、timing circuitry to this TDM input when transmitting TDM towards the end systems. 10.2 Reference clock available at the IWFs Figure 10-2 depicts the scenario wherein the two IWFs share a reference clock, distributed by means beyond the scope of this Recommendation. Each IWF uses the reference clock
49、to generate the timing used to transmit TDM data towards the end system. The end systems slave their timing circuitry to this TDM input when transmitting TDM towards the IWF. A scenario wherein one TDM network functions according to 10.1, and the other according to this clause, may also be possible. Figure 10-2/Y.1413 Reference clock available at IWFs 10.3 Common clock available at IWFs Figure 10-3 depicts the scenario wherein TDM end system 2 is required to slave it
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