1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T Y.1281TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (09/2003) SERIES Y: GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT GENERATION NETWORKS Internet protocol aspects Architecture, access, network capabilities and resource managemen
2、t Mobile IP services over MPLS ITU-T Recommendation Y.1281 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 Y.
3、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, networ
4、k 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 fu
5、nctional 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 Network m
6、anagement 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.1281 (09/2003) i ITU-T Recommendation Y.1281 Mobile IP services over MPLS Summa
7、ry This Recommendation defines service definition and requirements to support mobile IP services through the MPLS network. It also describes the service architecture and application procedures to provide the mobility service over the MPLS network. Source ITU-T Recommendation Y.1281 was approved by I
8、TU-T Study Group 13 (2001-2004) under the ITU-T Recommendation A.8 procedure on 13 September 2003. Keywords CR-LDP, Home Agent (HA), Foreign Agent (FA), IP-in-IP Tunnel, Label Edge Router (LER), Label Switched Path (LSP), Label Switched Router (LSR), LDP, mobile IPv4, mobile IPv6, MPLS, Quality of S
9、ervice (QoS), route optimization, RSVP-TE, Smooth Handover, Virtual Private Network (VPN). ii ITU-T Rec. Y.1281 (09/2003) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Se
10、ctor (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 on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets eve
11、ry 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 down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purvie
12、w, 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 telecommunication administration and a recognized operating agency. Compliance with this Recommendation is volunt
13、ary. However, the Recommendation may contain certain mandatory provisions (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 n
14、egative equivalents are used to express requirements. The use of such words 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 th
15、e 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 development process. As of the date of approval of this Recommenda
16、tion, 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 therefore strongly urged to consult the TSB patent database. ITU 20
17、03 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. Y.1281 (09/2003) iii CONTENTS Page 1 Scope 1 2 References. 1 2.1 Normative References 1 2.2 Informative References 2 3 Terms and Definitions 3 4 Abb
18、reviations 5 5 Service definitions and requirements 7 5.1 Service definitions 7 5.2 Service requirements 7 6 Service architecture 9 6.1 Overview 9 6.2 Reference architecture 10 6.3 LSP tunnelling scenarios 11 7 Application procedures for mobility support 14 7.1 General assumptions. 14 7.2 LSP tunnel
19、ling procedures . 15 7.3 Agent discovery 20 7.4 LSP rerouting procedures during handover 21 8 QoS considerations . 26 9 Management aspects. 27 10 Security aspects 27 11 Routing aspects. 28 12 Scalability considerations . 28 13 Consideration of migration from mobile IPv4 over MPLS to mobile IPv6 over
20、 MPLS 28 14 Interworking with mobile IP networks. 29 Appendix I Reference architectures for mobile IPv4 and mobile IPv6 networks . 29 I.1 Reference architecture of a mobile IPv4 network 29 I.2 Reference architecture of a mobile IPv6 network 30 iv ITU-T Rec. Y.1281 (09/2003) Introduction This Recomme
21、ndation defines service definition and requirements to support mobile IP services through the MPLS network. It also describes the service architecture and application procedures to provide the mobility service over the MPLS network. In the mobile IP network, a nodes IP address uniquely identifies th
22、e nodes point of attachment. Therefore, a mobile node must be located on the network indicated by its IP address in order to receive packets destined to it. Otherwise, packets destined to the mobile node would be undeliverable. In order not to lose its ability to communicate whenever it changes its
23、point of attachment, the mobile node must change its IP address. The IP address of mobile node must be advertised through the entire Internet to receive packets whenever it moves. The link by which a mobile node is directly attached to the Internet may often be a wireless link 7. Mobile IP is intend
24、ed to enable nodes to move from one IP subnet to another. This makes mobile IP suitable for mobility across heterogeneous media. If the mobile node moves from one LAN segment to another (e.g., a wireless LAN), the mobile nodes IP address remains the same after such a movement in order to receive pac
25、kets from other nodes. In fact, a mobile node is given a long-term IP address on a home network, the “home“ address. This home address is administered in the same way that a “permanent“ IP address is provided to a fixed host. When away from its home network, a “care-of address“ is associated with th
26、e mobile node and reflects the mobile nodes current point of attachment. When away from home, mobile IP uses protocol tunnelling to hide a mobile nodes home address to routers between its home network and its current location. The tunnel terminates at the mobile nodes care-of address 8. The care-of
27、address must be an address to which packets can be delivered via conventional IP routing. At the point of care-of address, the original packet is extracted from the tunnel and is delivered to the mobile node. In the basic mobile IPv4 protocol, there is no direct routing from any correspondent node t
28、o any mobile node. Packets need to pass through the mobile nodes home network and be forwarded by its home agent, which is called the problem of “triangle routing“. To solve this problem, the route optimization capability allows direct routing from any correspondent node to any mobile node 19. In IP
29、v6 network, IPv6 node caches the binding of a mobile nodes home address with its care-of address, and then sends any packets destined to the mobile node directly to this care-of address. To support this operation, mobile IPv6 defines an IPv6 protocol and a destination option 29. All IPv6 nodes, whet
30、her mobile or stationary, support communications with mobile nodes. From the network providers point of view, future networks are designed to support network operation and maintenance by guaranteeing acceptable quality of service (QoS) levels and satisfying various service level agreements (SLAs) ne
31、gotiated with customers. To support future business models, the IP network has to be upgraded to meet the demands placed by real-time and multimedia applications. It then provides various features such as fault tolerance, traffic prioritization, and QoS classes. To meet these requirements over futur
32、e mobile services, first, the end-to-end performance would be manageable and predictable regardless of whether end users are moving or not. Second, for the mobile IP service, the functions of home agent and foreign agent are positioned after consideration of architectural consequences. Third, the ex
33、isting and future transport technologies, including an optical one, would be able to support a future mobile world. In the MPLS network, once a packet is classified according to quality of service, no further header analysis is done by subsequent routers: all forwarding is driven by the labels. This
34、 has a number of advantages over conventional IP layer forwarding. The MPLS forwarding can be done by switches which are capable of doing label lookup and replacement at adequate speed and QoS. There is no need to analyze the IP layer headers. Sometimes it is desirable to force a packet to follow a
35、particular route which is explicitly chosen at or before the time the packet enters the network, rather than being chosen by the normal dynamic routing algorithm as the packet travels through the ITU-T Rec. Y.1281 (09/2003) v network. This may be done as a matter of policy, or supporting MPLS traffi
36、c engineering. In MPLS, a label can be used to represent this explicit route, which is called a traffic engineered tunnel. For mobile IP service, the home agent intercepts packets on the home link destined to the mobile IP nodes home address, encapsulates them, and tunnels them to the mobile nodes r
37、egistered care-of address via the foreign agent. The foreign agent decapsulates and delivers packets to the mobile IP node. By combining tunnelling functions of a home agent and a foreign agent into the MPLS forwarding paradigm, the MPLS node is capable of handling the mobile IP node by assigning la
38、bels for a tunnel between a home agent and a foreign agent. In this case, the home agent and the foreign agent can be located or attached at a MPLS node, the tunnelling between the home agent and the foreign agent being provided at the MPLS layer. To avoid the problem of triangle routing, the MPLS n
39、odes can allow a direct binding, which is the same with routing optimization of IP layer, from any correspondent node to any mobile IP node by assigning a label. As far as the support of the MPLS network is concerned, the MPLS network can provide the QoS-enabled and reliable tunnels for mobile IP se
40、rvice for the various sets of service requirements. The MPLS tunnelling capabilities can be implemented at the layer 2 level rather than the layer 3 mobile IP protocol level, then achieving higher service rate and lower overhead during tunnelling operation. Specifically, the MPLS network supporting
41、the mobile IP services has the following features: The flow concept of MPLS network provides the connection-oriented virtual channel capability with acceptable quality of service (QoS) levels for transfer delay and loss. A direct cut-through tunnel between the mobile node and the correspondent node
42、may be established while the mobile IPv4 protocol does not support it. This can save overall resource consumption and reduce the processing overhead of home agent. The binding cache information of the mobile IPv6 protocol can be mapped one-to-one to the MPLS label information table in each MPLS node
43、, without requiring any complex interworking feature. If the home agents and/or the foreign agents can be located at the MPLS node, the L3 tunnels between the home agents and the foreign agents can be mapped into the L2 tunnels of the MPLS layer. The mobile agents and mobile nodes do not need any kn
44、owledge of the MPLS backbone network. This means that the mobile IPv4 and mobile IPv6 nodes do not need to modify their tunnelling procedures through the MPLS backbone network. The MPLS network can provide seamless end-to-end connectivity without any performance degradation during handover operation
45、s (smooth handover). ITU-T Rec. Y.1281 (09/2003) 1 ITU-T Recommendation Y.1281 Mobile IP services over MPLS 1 Scope The scope of this Recommendation covers: Service requirements and definitions for mobile IPv4 and mobile IPv6 services over MPLS; Service architecture to support mobile IP service over
46、 MPLS; LSP tunnelling scenarios to support the mobile IP services over MPLS; Application procedures to support the mobile IP services over MPLS. However, this Recommendation does not cover: The detailed signalling protocol and packet formats for tunnel establishment; The detailed interworking proced
47、ures between the external mobile IP network and the MPLS network including traffic and QoS parameters; The mapping and conversion procedures between the IP-in-IP tunnels inside the mobile IP network and the LSP tunnels of the MPLS network; Coverage of more than one MPLS administrative domain; QoS ne
48、gotiation procedures between mobile IP nodes and the MPLS network; Routing algorithms of MPLS network with mobility support. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. A
49、t 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 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. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. 2
