1、 International Telecommunication Union ITU-T Y.2112TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (06/2007) SERIES Y: GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS Next Generation Networks Quality of Service and performance A QoS control architecture for
2、Ethernet-based IP access networks ITU-T Recommendation Y.2112 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 Network aspects
3、 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 Architecture, access, net
4、work 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 NETWORKS Frameworks and
5、 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.2300Y.2399 Networ
6、k 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.2112 (06/2007) i ITU-T Recommendation Y.2112 A QoS control architecture for
7、Ethernet-based IP access networks Summary ITU-T Recommendation Y.2112 specifies a QoS control architecture for Ethernet-based IP access networks. By applying the resource and admission control functions specified in ITU-T Recommendation Y.2111 and Ethernet-specific QoS mechanisms, it enables dynamic
8、 QoS control in the access network for a variety of services, such as voice over IP, video on demand and bandwidth on demand. Source ITU-T Recommendation Y.2112 was approved on 13 June 2007 by ITU-T Study Group 13 (2005-2008) under the ITU-T Recommendation A.8 procedure. ii ITU-T Rec. Y.2112 (06/200
9、7) 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 studying technical, operating and tariff questions a
10、nd 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 groups which, in turn, produce Recommendations on th
11、ese 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 ISO and IEC. NOTE In this Recommendation, the exp
12、ression “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 provisions (to ensure e.g., interoperability or applicab
13、ility) 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 words does not suggest that compliance with the
14、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 concerning the evidence, validity or applicabili
15、ty 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 implement t
16、his Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2008 All rights reserved. No part of this publication may be reproduced, by any means wh
17、atsoever, without the prior written permission of ITU. ITU-T Rec. Y.2112 (06/2007) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Definitions 1 3.1 Terms defined elsewhere 1 3.2 Terms defined in this Recommendation. 2 4 Abbreviations and acronyms 2 5 Conventions 4 6 Ethernet-based IP access network r
18、eference models 4 7 Requirements for support of dynamic QoS control 5 8 Functional architecture for support of dynamic QoS control . 6 8.1 Overview 6 8.2 QoS mechanisms 7 8.3 Resource and admission control function (RACF) 7 8.4 Policy decision functional entity (PD-FE) . 7 8.5 Transport resource con
19、trol functional entity (TRC-FE). 7 8.6 Transport functions. 8 9 Reference point requirements. 9 9.1 Rs between SCF and PD-FE. 10 9.2 Rt between PD-FE and TRC-FE 10 9.3 Ru between PD-FE and NACF. 10 9.4 Rw between PD-FE and PE-FE 10 9.5 Rc between TRC-FE and access network nodes 10 9.6 Rn between TRC
20、-FE and TRE-FE. 10 10 Procedures for support of dynamic QoS control 10 10.1 Network topology and resource attributes collection. 11 10.2 Resource allocation 11 10.3 Resource modification 12 10.4 Resource release . 12 10.5 Failure handling 12 11 Deployment scenarios. 14 12 Security considerations. 14
21、 Appendix I Ethernet-based IP access networks and QoS . 15 Appendix II Last-mile user access technology . 17 iv ITU-T Rec. Y.2112 (06/2007) Page Appendix III Use cases . 18 III.1 Overview 18 III.2 Voice over IP 18 III.3 Video on demand 19 III.4 Bandwidth on demand 19 Bibliography. 21 ITU-T Rec. Y.21
22、12 (06/2007) 1 ITU-T Recommendation Y.2112 A QoS control architecture for Ethernet-based IP access networks 1 Scope This Recommendation specifies a quality of service (QoS) control architecture and requirements covering aspects, such as resource reservation, admission control and gate control, for E
23、thernet-based IP access networks. Based on the resource and admission control functions (RACF) as defined in ITU-T Y.2111, this Recommendation provides details specific to Ethernet-based IP access networks. An Ethernet-based IP access network is an IP access network which comprises the Ethernet aggr
24、egation network, access nodes, and edge nodes, and may also include the IP aggregation network. In this Recommendation, the Ethernet aggregation network supports VLANs as defined in b-IEEE 802.1Q and b-IEEE 802.1ad. Note that the QoS mechanisms for the last mile user access segment are MAC technolog
25、y-specific and as such are out of the scope of this Recommendation. 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 va
26、lid. 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 Recommendation
27、s 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 Y.1231 ITU-T Recommendation Y.1231 (2000), IP access network architecture. ITU-T Y.2091 ITU-T Recommendation Y.2091 (2007), Terms and de
28、finitions for Next Generation Networks. ITU-T Y.2111 ITU-T Recommendation Y.2111 (2006), Resource and admission control functions in Next Generation Networks. 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following terms defined elsewhere: 3.1.1 absolute QoS ITU-T Y.2111: Th
29、is term refers to a traffic delivery service with numerical bounds on some or all of the QoS parameters. These bounds may be physical limits, or enforced limits such as those encountered through mechanisms like rate policing. The bounds may result from designating a class of network performance obje
30、ctives for packet transfer. 3.1.2 gate control ITU-T Y.2111: The operation of opening or closing a gate. When a gate is open, the packets in the media flows are allowed to pass through; when a gate is closed, the packets in the media flows are not allowed to pass through. 2 ITU-T Rec. Y.2112 (06/200
31、7) 3.1.3 IP access network ITU-T Y.1231: An implementation comprising network entities to provide the required access capabilities between an “IP user“ and an “IP service provider“ for the provision of IP services. “IP user“ and “IP service provider“ are logical entities which terminate the IP layer
32、 and/or IP related functions, and may also include lower layer functions. 3.1.4 IP core network ITU-T Y.1231: IP service providers network, including one or more IP service providers. 3.1.5 media flow ITU-T Y.2111: A unidirectional media stream, which is specified by two endpoint identifiers and ban
33、dwidth, as well as class of service, if needed. 3.1.6 relative QoS ITU-T Y.2111: This term refers to a traffic delivery service without absolute bounds on the achieved bandwidth, packet delay or packet loss rates. It describes circumstances where certain classes of traffic are handled differently fr
34、om other classes of traffic, and the classes achieve different levels of QoS. 3.1.7 session ITU-T Y.2091: A temporary telecommunication relationship among a group of objects in the service stratum that are assigned to collectively fulfil a task for a period of time. A session has a state that may ch
35、ange during its lifetime. Session-based telecommunications may, but need not be, assisted by intermediaries (see mediated services). Session-based telecommunications can be one-to-one, one-to-many, many-to-one, or many-to-many. 3.2 Terms defined in this Recommendation This Recommendation defines the
36、 following terms: 3.2.1 edge router: An edge router is a router that operates at the edge of access network and aggregates IP datagrams from access network into the core network. 3.2.2 Ethernet-based IP access network: An IP access network that comprises the Ethernet aggregation network, access node
37、s (such as DSLAM), and edge nodes (such as BRAS) and may also include the IP aggregation network. Edge nodes are typically IP capable. Access nodes may be IP capable. 3.2.3 IP flow: A sequence of packets sent from a particular source to a particular destination, to which common routing is applied. 3
38、.2.4 last mile user access: The portion of the access network between the CPE and the access node. NOTE If using IPv4, a flow is identified by the IPv4 5-tuple which includes source/destination IP addresses, protocol ID and source/destination port numbers. If using IPv6, a flow is identified by the
39、IPv6 3-tuple which includes source/destination IP addresses and flow label. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: AAA Authentication, Authorization and Accounting AN Access Node APP Application Layer BE Best Effort BoD Bandwidth on Demand BRA
40、S Broadband Remote Access Server CDN Content Delivery Network CPE Customer Premises Equipment ITU-T Rec. Y.2112 (06/2007) 3 CPN Customer Premises Network DHCP Dynamic Host Configuration Protocol DSCP Differentiated Services Code Point DSL Digital Subscriber Line DSLAM Digital Subscriber Line Access
41、Multiplexer DST Destination EAP Extensible Authentication Protocol EN Edge Node ER Edge Router EXP Experimental bits GRE Generic Routing Encapsulation HTTP HyperText Transfer Protocol ID Identifier IMN InterMediate Node IP Internet Protocol L2TP Layer 2 Tunnelling Protocol LLDP Link Layer Discovery
42、Protocol LSP Label Switched Path MAC Media Access Control MPLS Multi-Protocol Label Switching NACF Network Attachment Control Function PD-FE Policy Decision Functional Entity PE-FE Policy Enforcement Functional Entity PHB Per Hop Behaviour PHY Physical Layer PPP Point-to-Point Protocol QoS Quality o
43、f Service RACF Resource and Admission Control Function RSVP Resource ReSerVation Protocol SCF Service Control Function SLA Service Level Agreement SNMP Simple Network Management Protocol SRC Source STP Spanning Tree Protocol S-VLAN Service Virtual Local Area Network TCP Transmission Control Protocol
44、 TRC-FE Transport Resource Control Functional Entity 4 ITU-T Rec. Y.2112 (06/2007) TRE-FE Transport Resource Enforcement Functional Entity UDP User Datagram Protocol UMTS Universal Mobile Telecommunications System VoD Video on Demand VoIP Voice over IP VPN Virtual Private Network WLAN Wireless Local
45、 Area Network 5 Conventions This clause is intentionally left blank. 6 Ethernet-based IP access network reference models This Recommendation assumes that the Ethernet-based IP access network is comprised of: a last mile user access facility, an Ethernet aggregation network, an access node that may b
46、e IP capable (e.g., DSLAM), an edge node that is IP capable (e.g., BRAS) and may also include the IP aggregation network. See Figure 1 below. It also assumes that an Ethernet-based IP access network may support several different types of the last mile user access technologies. For example, an Ethern
47、et-based IP DSLAM may support LAN/xDSL/WLAN user access, and different types of access nodes may be deployed and aggregated to the same BRAS. Additionally, it assumes that the BRAS may serve as an edge router; in that case there is no IP level aggregation performed. In this Recommendation, the edge
48、node (EN) acts as the egress of upstream traffic that connects the IP access network to the core network. It may represent either a BRAS or ER. Y.2112(07)_F.01TETETEIP routerModemAccessnodeEdgerouterBRASIP level aggregation networkEthernetlevel aggregation networkEthernet-based IP access networkNetw
49、orkoperator 1Networkoperator NIP core networkLast mile user accessHome gatewayCPNFigure 1 Generic architectural and topological model of Ethernet-based IP access network Generally, L2 or L3 switches are used for Ethernet level traffic aggregation per subscriber, and L3 switches or IP routers are used for IP level aggregation per QoS class or service type. Home gateways may consist of modems and an IP router; however, either element can be optional depending on the type of last mile user access technology. The access node ter
