1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T X.149TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (10/2003) SERIES X: DATA NETWORKS AND OPEN SYSTEM COMMUNICATIONS Public data networks Network aspects Performance of IP networks when supported by public Frame Relay data networks ITU-T Recommendation X
2、.149 ITU-T X-SERIES RECOMMENDATIONS DATA NETWORKS AND OPEN SYSTEM COMMUNICATIONS PUBLIC DATA NETWORKS Services and facilities X.1X.19 Interfaces X.20X.49 Transmission, signalling and switching X.50X.89 Network aspects X.90X.149 Maintenance X.150X.179 Administrative arrangements X.180X.199 OPEN SYSTE
3、MS INTERCONNECTION Model and notation X.200X.209 Service definitions X.210X.219 Connection-mode protocol specifications X.220X.229 Connectionless-mode protocol specifications X.230X.239 PICS proformas X.240X.259 Protocol Identification X.260X.269 Security Protocols X.270X.279 Layer Managed Objects X
4、.280X.289 Conformance testing X.290X.299 INTERWORKING BETWEEN NETWORKS General X.300X.349 Satellite data transmission systems X.350X.369 IP-based networks X.370X.399 MESSAGE HANDLING SYSTEMS X.400X.499 DIRECTORY X.500X.599 OSI NETWORKING AND SYSTEM ASPECTS Networking X.600X.629 Efficiency X.630X.639
5、 Quality of service X.640X.649 Naming, Addressing and Registration X.650X.679 Abstract Syntax Notation One (ASN.1) X.680X.699 OSI MANAGEMENT Systems Management framework and architecture X.700X.709 Management Communication Service and Protocol X.710X.719 Structure of Management Information X.720X.72
6、9 Management functions and ODMA functions X.730X.799 SECURITY X.800X.849 OSI APPLICATIONS Commitment, Concurrency and Recovery X.850X.859 Transaction processing X.860X.879 Remote operations X.880X.899 OPEN DISTRIBUTED PROCESSING X.900X.999 For further details, please refer to the list of ITU-T Recom
7、mendations. ITU-T Rec. X.149 (10/2003) i ITU-T Recommendation X.149 Performance of IP networks when supported by public Frame Relay data networks Summary The key objective of this Recommendation is to provide an estimate of the IP layer performance obtained in the case where Frame Relay network infr
8、astructure is used to provide the lower layer connectivity to transport the IP packets between the routers. Mappings between Frame Relay and IP performance parameters are presented. Numerical values of IP performance parameters are estimated based on the objective values specified for the Frame Rela
9、y performance parameters specified in ITU-T Rec. X.146. A general model for the calculation of transfer delay is presented. This model can be used to assist in the planning of networks. The analysis presented provides an upper bound on the performance that could be achieved by an IP network when car
10、ried over a Frame Relay network. The performance mappings between FR and IP networks specified are seen as complementary to ITU-T Rec. Y.1541, since ITU-T Rec. Y.1541 is technology independent with regard to the provision of the physical and link layers. Accordingly, this Recommendation does not spe
11、cify end-to-end performance objectives, but illustrates the way in which the Y.1541 objectives could be supported. Source ITU-T Recommendation X.149 was approved by ITU-T Study Group 17 (2001-2004) under the ITU-T Recommendation A.8 procedure on 29 October 2003. Keywords Frame Relay networks, IP net
12、works, Performance. ii ITU-T Rec. X.149 (10/2003) 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 of ITU. ITU-T is responsible for study
13、ing 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 topics for study by the ITU-T study group
14、s 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 prepared on a collaborative basis with IS
15、O and IEC. NOTE In this Recommendation, the expression “Administration“ 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 provision
16、s (to ensure e.g. interoperability or applicability) and compliance 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 wo
17、rds does not suggest that compliance with the Recommendation is required 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 co
18、ncerning the evidence, validity or applicability of claimed Intellectual 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 not received notice of intellectual property, protected by
19、 patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. ITU 2004 All rights reserved. No part of this publication may be reproduced, b
20、y any means whatsoever, without the prior written permission of ITU. ITU-T Rec. X.149 (10/2003) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Definitions 2 3.1 Definition of IP and Frame Relay performance parameters. 2 4 Abbreviations 3 5 Conventions 4 6 General model for interconnecting IP routers
21、via Frame Relay. 4 7 Layered model of performance for IP services. 5 8 Generic IP service performance model. 6 8.1 Network components, circuit sections and network sections. 6 8.2 Reference path for UNI-to-UNI Quality of Service assessment 6 9 Encapsulation of an IP packet into a Frame Relay frame.
22、7 10 Analytical relationship between IP and Frame Relay performance parameters. 8 10.1 Loss performance . 8 10.2 Delay performance . 8 10.3 IP Delay Variation (IPDV) performance 8 11 Mapping IP performance to Frame Relay QoS classes 9 11.1 Mapping of FLR to IPLR . 9 11.2 Mapping of FRTD to IPTD 10 1
23、2 Implications for planning IP networks . 10 Annex A General transfer delay model. 10 A.1 Transfer delay model 10 A.2 Components of delay 11 Annex B Use of the transfer delay model in planning IP networks 13 B.1 Use of the transfer delay model 13 B.2 Design of an IP section to meet the Classes 0 and
24、 2 IPTD objective. 14 Appendix I Effect of packet/frame size on the IP transfer delay 16 I.1 Estimate of IP packet transfer delay using the model 16 Appendix II Use of Frame Relay for support of the IP service classes defined in ITU-T Rec. Y.1541 18 II.1 Simple interconnection of IP routers 18 II.2
25、Calculation of end-to-end delay . 19 II.3 Estimation of the IPDV 20 II.4 Estimation of IP Packet Loss ratio (IPLR). 20 Appendix III General network architecture for an IP network . 21 III.1 General network architecture for an IP network 21 III.2 IP access network reference model 21 iv ITU-T Rec. X.1
26、49 (10/2003) Page Appendix IV Definition of network components, circuit sections and network sections. 22 IV.1 Network components 22 IV.2 Circuit sections and network sections 23 Appendix V IP network QoS classes (as per ITU-T Rec. Y.1541) 24 ITU-T Rec. X.149 (10/2003) 1ITU-T Recommendation X.149 Pe
27、rformance of IP networks when supported by public Frame Relay data networks 1 Scope The key objective of this Recommendation is to specify the end-to-end performance that could be achieved by an IP network when the backbone network providing the connectivity between the IP routers is provided by Fra
28、me Relay infrastructure. This Recommendation does not specify end-to-end performance objectives for IP networks. The Recommendation provides an estimate of the IP layer performance obtained when Public Frame Relay Data Networks are used to transport the IP packets and indicates how the IP QoS classe
29、s defined in ITU-T Rec. Y.1541 could be supported. The Recommendation provides an analysis of the mappings between the Frame Relay and IP performance parameters. Numerical values of the expected IP performance parameters are derived from the objective values specified for the Frame Relay Performance
30、 parameters as specified in ITU-T Rec. X.146. Using a general model an analysis of the expected performance for various IP packet sizes (corresponding to various IP applications) and the influence of the Frame Relay network infrastructure (e.g., inter-node transmission trunks) is provided. This anal
31、ysis provides an upper bound on the performance that could be achieved by an IP network when carried over a Frame Relay network, since the IP network infrastructure could increase both the achieved IP packet transit delay and IP packet loss rate. This Recommendation, and in particular the performanc
32、e parameter mappings between Frame Relay and IP networks, is seen as complementary to ITU-T Rec. Y.1541, since ITU-T Rec. Y.1541 is technology independent with regard to the provision of the physical and link layers. The scope of the Recommendation is limited to IP networks where the link infrastruc
33、ture is provided by or supported by Public Frame Relay Data Networks. 2 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
34、valid. All Recommendations and 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 Recommendati
35、ons is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T Recommendation E.651 (2000), Reference connections for traffic engineering of IP access networks. ITU-T Recommendation G.114 (2003), O
36、ne-way transmission time. ITU-T Recommendation G.1000 (2001), Communications Quality of Service: A framework and definitions. ITU-T Recommendation G.1010 (2001), End-user multimedia QoS categories. ITU-T Recommendation X.36 (2003), Interface between Data Terminal Equipment (DTE) and Data Circuit-ter
37、minating Equipment (DCE) for public data networks providing frame relay data transmission service by dedicated circuit. 2 ITU-T Rec. X.149 (10/2003) ITU-T Recommendation X.76 (2003), Network-to-network interface between public networks providing PVC and/or SVC frame relay data transmission service.
38、ITU-T Recommendation X.140 (1992), General quality of service parameters for communication via public data networks. ITU-T Recommendation X.144 (2003), User information transfer performance parameters for public frame relay data networks. ITU-T Recommendation X.145 (2003), Connection establishment a
39、nd disengagement performance parameters for public Frame Relay data networks providing SVC services. ITU-T Recommendation X.146 (2000), Performance objectives and quality of service classes applicable to frame relay. ITU-T Recommendation Y.1221 (2002), Traffic control and congestion control in IP-ba
40、sed networks. ITU-T Recommendation Y.1231 (2000), IP Access Network Architecture. ITU-T Recommendation Y.1540 (2002), Internet protocol data communication service IP packet transfer and availability performance parameters. ITU-T Recommendation Y.1541 (2002), Network performance objectives for IP-bas
41、ed services. IETF RFC 791 (1981), Internet Protocol, DARPA Internet Program Protocol Specification. 3 Definitions The terms and their definitions used in this Recommendation are consistent with those defined in ITU-T Recs X.36, X.76, X.144, X.145, X.146, Y.1231, Y.1540, and Y.1541. Appendix III prov
42、ides the general network architecture for an IP network as per ITU-T Rec. Y.1231. Appendix IV provides a description (based on ITU-T Rec. Y.1540) of the network components together with the circuit and network sections that provide the building blocks with which any end-to-end IP service may be repr
43、esented. 3.1 Definition of IP and Frame Relay performance parameters The definitions (as per ITU-T Rec. Y.1540) of IP Loss Ratio and Frame Loss Ratio are presented here for clarity. 3.1.1 IP Packet performance parameters 3.1.1.1 IP packet loss ratio (IPLR): IP Packet Loss Ratio is the ratio of the t
44、otal lost IP packet outcomes to total transmitted IP packets in a population of interest. “Lost IP packet outcomes“ and “Populations of Interest“ are defined in ITU-T Rec. Y.1540. 3.1.1.2 IP packet transfer delay (IPTD): IP packet transfer delay is defined for all successful and errored packet outco
45、mes across a basic section or an NSE. IPTD is the time (t2 t1) between the occurrence of two corresponding IP packet reference events, ingress event IPRE1at time t1and egress event IPRE2at time t2, where (t2 t1) and (t2 t1) Tmax. Network Section Ensemble (NSE) and IP Reference Events (IPRE) are defi
46、ned in ITU-T Rec. Y.1540. 3.1.2 Frame Relay performance parameters The definition of Frame Loss Ratio and Frame Transfer Delay (as per packet transfer X.144) are presented here for clarity. ITU-T Rec. X.149 (10/2003) 33.1.2.1 frame loss ratio: The user information Frame Loss Ratio (FLR) is defined a
47、s: ESLFFFFFLR+=Lwhere, in a specified population: FSis the total number of successively transferred frame outcomes; FLis the total number of lost frame outcomes; and FEis the total number of residually errored frame outcomes. The objective values for frame loss ratio specified in the Frame Relay QoS
48、 classes in ITU-T Rec. X.146, correspond to a special case of the above ratio. This is the FLRC. The FLR for frames marked with the discard eligibility bit set to zero DE = 0 should remain relatively constant as long as the total DE = 0 traffic does not exceed the Committed Information Rate (CIR). I
49、f the network accepts all conforming frames, FLRCis the probability that a DE = 0 frame accepted as conforming will subsequently be lost. DE = 0 frames relayed with the DE bit changed to DE = 1 are included in the calculation of FLRC. 3.1.2.2 user information frame transfer delay: The user information frame transfer delay (FTD) is defined as: FTD = t2 t1where, in a specified population: t1is the time of occurrence for the first FE (Frame Layer Reference Event); t2is the time of occurrence for the
