1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T I.378TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (12/2002) SERIES I: INTEGRATED SERVICES DIGITAL NETWORK Overall network aspects and functions General network requirements and functions Traffic control and congestion control at the ATM Adaptation Laye
2、r type 2 ITU-T Recommendation I.378 ITU-T I-SERIES RECOMMENDATIONS INTEGRATED SERVICES DIGITAL NETWORK GENERAL STRUCTURE Terminology I.110I.119 Description of ISDNs I.120I.129 General modelling methods I.130I.139 Telecommunication network and service attributes I.140I.149 General description of asyn
3、chronous transfer mode I.150I.199 SERVICE CAPABILITIES Scope I.200I.209 General aspects of services in ISDN I.210I.219 Common aspects of services in the ISDN I.220I.229 Bearer services supported by an ISDN I.230I.239 Teleservices supported by an ISDN I.240I.249 Supplementary services in ISDN I.250I.
4、299 OVERALL NETWORK ASPECTS AND FUNCTIONS Network functional principles I.310I.319 Reference models I.320I.329 Numbering, addressing and routing I.330I.339 Connection types I.340I.349 Performance objectives I.350I.359 Protocol layer requirements I.360I.369 General network requirements and functions
5、I.370I.399 ISDN USER-NETWORK INTERFACES Application of I-series Recommendations to ISDN user-network interfaces I.420I.429 Layer 1 Recommendations I.430I.439 Layer 2 Recommendations I.440I.449 Layer 3 Recommendations I.450I.459 Multiplexing, rate adaption and support of existing interfaces I.460I.46
6、9 Aspects of ISDN affecting terminal requirements I.470I.499 INTERNETWORK INTERFACES I.500I.599 MAINTENANCE PRINCIPLES I.600I.699 B-ISDN EQUIPMENT ASPECTS ATM equipment I.730I.739 Transport functions I.740I.749 Management of ATM equipment I.750I.759 Multiplexing aspects I.760I.769 For further detail
7、s, please refer to the list of ITU-T Recommendations. ITU-T Rec. I.378 (12/2002) i ITU-T Recommendation I.378 Traffic control and congestion control at the ATM Adaptation Layer type 2 Summary This Recommendation provides a general description as well as objectives and procedures for AAL type 2 traff
8、ic control and congestion control. It introduces the concept of AAL type 2 transfer capability. For each AAL type 2 transfer capability, it specifies AAL type 2 traffic parameters, an AAL type 2 conformance definition and defines AAL type 2 QoS commitments. Additionally, it describes the concepts of
9、 the AAL type 2 traffic contract. Source ITU-T Recommendation I.378 was prepared by ITU-T Study Group 13 (2001-2004) and approved under the WTSA Resolution 1 procedure on 14 December 2002. ii ITU-T Rec. I.378 (12/2002) FOREWORD The International Telecommunication Union (ITU) is the United Nations sp
10、ecialized 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 Recommendations on them with a view to standardizing telecommunications o
11、n 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 approval of ITU-T Recommendations is covered by the procedure laid d
12、own 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 “Administration“ is used for conciseness to indicate both a telecommunicatio
13、n administration and a recognized operating agency. 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
14、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 patents, which may be required to
15、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 2003 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the
16、 prior written permission of ITU. ITU-T Rec. I.378 (12/2002) iii CONTENTS Page 1 Scope 1 2 References. 1 2.1 Normative references 1 2.2 Informative references 1 3 Abbreviations 2 4 Introduction 2 5 AAL type 2 traffic parameters and descriptors. 3 5.1 Definitions 3 5.2 Requirements on AAL type 2 traf
17、fic parameters and AAL type 2 traffic descriptors. 3 5.3 AAL type 2 traffic parameter specifications 3 5.3.1 AAL type 2 reference configuration. 3 5.3.2 AAL type 2 traffic parameter description 5 6 AAL type 2 transfer capabilities. 6 6.1 Fixed Bandwidth (FBW) AAL type 2 transfer capability 6 6.1.1 D
18、escription . 6 6.1.2 Service model . 6 6.1.3 Traffic descriptor 6 6.1.4 Conformance definition 7 6.1.5 QoS commitments 7 6.2 Variable Bandwidth Stringent (VBW-S) AAL type 2 transfer capability . 7 6.2.1 Description . 7 6.2.2 Service model . 7 6.2.3 VBW-S traffic descriptor . 7 6.2.4 VBW-S conformanc
19、e definition. 7 6.2.5 QoS commitments 8 6.3 Variable Bandwidth Tolerant (VBW-T) AAL type 2 transfer capability 8 6.3.1 Description . 8 6.3.2 Service model . 8 6.3.3 VBW-T traffic descriptor . 8 6.3.4 VBW-T conformance definition. 8 6.3.5 QoS commitments 9 7 Functions for AAL type 2 traffic control a
20、nd AAL type 2 congestion control 9 7.1 Introduction to AAL type 2 traffic control and AAL type 2 congestion control functions. 9 7.1.1 AAL type 2 traffic control functions 9 iv ITU-T Rec. I.378 (12/2002) Page 7.1.2 AAL type 2 congestion control functions 9 7.2 AAL type 2 traffic control functions 9
21、7.2.1 AAL type 2 path resource management . 9 7.2.2 AAL type 2 connection admission control. 9 7.2.3 CPS packet discard control. 9 7.2.4 AAL type 2 traffic shaping. 10 7.2.5 AAL type 2 packet scheduling . 10 7.3 AAL type 2 congestion control functions 10 7.3.1 CPS packet discard control. 10 7.3.2 AA
22、L type 2 scheduling control 10 8 Methods and tools for AAL type 2 path resource management . 10 Appendix I Mapping of AAL type 2 traffic parameters . 10 Appendix II Guidelines for choosing AAL 2 parameter values for connections with control frames . 11 Appendix III Information on the source traffic
23、type and source traffic type set 12 ITU-T Rec. I.378 (12/2002) 1 ITU-T Recommendation I.378 Traffic control and congestion control at the ATM Adaptation Layer type 2 1 Scope This Recommendation describes traffic control and congestion control procedures at the AAL type 2 level as defined in 3. Such
24、control procedures are necessary in order to support AAL type 2 connections with QoS. AAL type 2 traffic control refers to all network actions aiming to meet the negotiated performance objectives at the AAL type 2 level and to allow the avoidance of congested conditions. AAL type 2 congestion contro
25、l refers to all network actions to minimize the intensity, spread and duration of congestion. This Recommendation provides a general description as well as objectives and procedures for AAL type 2 traffic control and congestion control. It introduces the concept of AAL type 2 transfer capability. Fo
26、r each AAL type 2 transfer capability, it specifies AAL type 2 traffic parameters, an AAL type 2 conformance definition and defines AAL type 2 QoS commitments. Additionally, it describes the concepts of the AAL type 2 traffic contract. 2 References The following ITU-T Recommendations and other refer
27、ences 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 and other references are subject to revision; users of this Recommendation are therefore encouraged to inve
28、stigate 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. The reference to a document within this Recommendation does not give it, as a stand-alone document, the st
29、atus of a Recommendation. 2.1 Normative references 1 ITU-T Recommendation I.371 (2000), Traffic control and congestion control in B-ISDN. 2 ITU-T Recommendation I.356 (2000), B-ISDN ATM layer cell transfer performance. 3 ITU-T Recommendation I.363.2 (2000), B-ISDN ATM Adaptation Layer: Type 2 AAL sp
30、ecification. 4 ITU-T Recommendation Q.2630.1 (1999), AAL type 2 signalling protocol Capability Set 1. 5 ITU-T Recommendation Q.2630.2 (2000), AAL type 2 signalling protocol Capability Set 2. 6 ITU-T Recommendation Y.1221 (2002), Traffic control and congestion control in IP-based networks. 7 ITU-T Re
31、commendation I.366.2 (2000), AAL type 2 service specific convergence sublayer for narrow-band services. 2.2 Informative references 8 3GPP TS 25.415 V3.5.0 (2000-12), UTRAN Iu Interface User Plane Protocols. 2 ITU-T Rec. I.378 (12/2002) 9 ETSI TS 126 071 V3.0.1 (2000-01), Universal Mobile Telecommuni
32、cation System (UMTS); Mandatory Speech Codec speech processing functions AMR Speech Codec General Description (3G TS 26.071 version 3.0.1 Release 1999). 10 ETSI TS 126 101 V3.0.0 (2000-01), Universal Mobile Telecommunication System (UMTS); Mandatory Speech Codec speech processing functions; AMR Spee
33、ch Codec Frame Structure (3G TS 26.101 version 3.0.0 Release 1999). 3 Abbreviations This Recommendation uses the following abbreviations. AAL type 2 ATM Adaptation Layer type 2 AMR Adaptive Multi-Rate ATC ATM Transfer Capability ATM Asynchronous Transfer Mode BPcps CPS Token Bucket Size associated w
34、ith the Peak CPS byte rate BScps CPS Token Bucket Size associated with the Sustainable CPS byte rate CPS Common Part Sublayer DBR Deterministic Bit Rate FBW Fixed Bandwidth GBRA Generic Byte Rate Algorithm IP Internet Protocol Mcps Maximum allowed CPS packet size PDU Protocol Data Unit PRcps Peak CP
35、S byte rate QoS Quality of Service SBR Statistical Bit Rate SCR Sustainable Cell Rate SDU Service Data Unit SRcps Sustainable CPS byte rate TB Token Bucket VBW-S Variable Bandwidth Stringent VBW-T Variable Bandwidth Tolerant VCC Virtual Channel Connection 4 Introduction The AAL type 2 was defined in
36、 3. An AAL type 2 connection uses one or several contiguous ATM VCCs called AAL type 2 paths. An AAL type 2 path can be shared by up to 248 AAL type 2 user connections. QoS for an AAL type 2 connection is then determined by: the QoS associated with the AAL type 2 paths (the ATM VCCs) along the conne
37、ction as defined in 2; ITU-T Rec. I.378 (12/2002) 3 the QoS supported by AAL type 2 multiplexing where the AAL type 2 connection is put inside an AAL type 2 path. The primary role of traffic control and congestion control procedures at the AAL type 2 level is to protect the AAL type 2 traffic when i
38、t is multiplexed onto an AAL type 2 path. The goal is to achieve the AAL type 2 performance objectives and AAL type 2 QoS commitments. Traffic and congestion control allows the use of AAL type 2 paths to be optimized. Congestion at the AAL type 2 level is defined as a state of network elements (e.g.
39、 AAL type 2 switches) in which the network is not able to meet the AAL type 2 performance objectives and the negotiated AAL type 2 QoS commitments for the established AAL type 2 flows. Congestion is to be distinguished from the state where buffer overflow causes CPS packet loss, but the negotiated q
40、uality of service is still met. This Recommendation defines a set of traffic control and congestion control capabilities at the AAL type 2 level. It may be appropriate to consider additional sets of such capabilities (for which additional traffic control mechanisms will be used) to achieve increased
41、 network efficiency. It should be noted that AAL type 2 traffic control procedures apply to AAL type 2 connections. For AAL type 2 connections, the network commits to meet QoS objectives, assuming the AAL type 2 connection conforms to a traffic contract. 5 AAL type 2 traffic parameters and descripto
42、rs 5.1 Definitions This Recommendation defines the following terms: 5.1.1 AAL type 2 traffic parameter: An AAL type 2 traffic parameter describes one aspect of an AAL type 2 connection. It may be qualitative or quantitative. An AAL type 2 traffic parameter may, for example, describe the peak byte ra
43、te, the average byte rate, the average or maximum CPS packet size, the burst length of an AAL type 2 connection, etc. 5.1.2 AAL type 2 traffic descriptor: An AAL type 2 traffic descriptor is the set of AAL type 2 traffic parameters that is used to capture the traffic characteristics of an AAL type 2
44、 connection as part of the AAL type 2 traffic contract. 5.1.3 AAL type 2 traffic contract: For a given AAL type 2 connection, the AAL type 2 traffic descriptor, the AAL type 2 conformance definition and the AAL type 2 QoS commitments define the AAL type 2 traffic contract. 5.2 Requirements on AAL ty
45、pe 2 traffic parameters and AAL type 2 traffic descriptors Any AAL type 2 traffic parameter to be involved in an AAL type 2 traffic descriptor should: have the same interpretation on both sides of an interface or within a network; be meaningful in resource allocation schemes to meet network performa
46、nce requirements; be enforceable by the parameter control. Whether an AAL type 2 parameter should be enforced is for further study. 5.3 AAL type 2 traffic parameter specifications 5.3.1 AAL type 2 reference configuration An AAL type 2 connection has a starting point (AAL type 2 source) and an endpoi
47、nt (AAL type 2 destination). An AAL type 2 connection uses one or several AAL type 2 paths. AAL type 2 traffic parameters are defined at the AAL type 2 source. They are valid along the whole AAL type 2 4 ITU-T Rec. I.378 (12/2002) connection even though the traffic characteristics of the AAL type 2
48、connection may change due to AAL type 2 packet delay variation after the CPS packets pass through several AAL type 2 paths. I.378_F01AAL type 2sourceATM switch AAL type 2controlAAL type 2destinationHigherlayerAAL type 2CPSATMPhys. mediaATMPhys. mediaATMPhys. mediaAAL type 2CPSATMPhys. mediaAAL type
49、2CPSATMPhys. mediaHigherlayerAAL type 2CPSATMPhys. mediaAAL type 2 link AAL type 2 linkAAL type 2 connectionFigure 1/I.378 Reference configuration for one AAL type 2 connection I.378_F02AAL type 2sourceATM switchHigher layer network elementAAL type 2destinationHigherlayerAAL type 2CPSATMPhys. mediaATMPhys. mediaATMPhys. mediaAAL type 2CPSATMPhys. mediaAAL type 2CPSATMPhys. mediaHigherlayerAAL type 2CPSATMPhys. mediaAAL type 2 connectionAAL type 2sourceAAL type 2destinationHigh
