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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) -- Looks like a reference, but probably isn't: '1' on line 607 ** Obsolete normative reference: RFC 3107 (Obsoleted by RFC 8277) ** Obsolete normative reference: RFC 3344 (Obsoleted by RFC 5944) ** Obsolete normative reference: RFC 3775 (Obsoleted by RFC 6275) Summary: 4 errors (**), 0 flaws (~~), 5 warnings (==), 8 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group O. Berzin 3 Internet-Draft A. Malis 4 Expires: October 30, 2008 Verizon Communications 5 April 28, 2008 7 Mobility Support Using MPLS and MP-BGP Signaling 8 draft-berzin-malis-mpls-mobility-01.txt 10 Status of this Memo 12 By submitting this Internet-Draft, each author represents that any 13 applicable patent or other IPR claims of which he or she is aware 14 have been or will be disclosed, and any of which he or she becomes 15 aware will be disclosed, in accordance with Section 6 of BCP 79. 17 Internet-Drafts are working documents of the Internet Engineering 18 Task Force (IETF), its areas, and its working groups. Note that 19 other groups may also distribute working documents as Internet- 20 Drafts. 22 Internet-Drafts are draft documents valid for a maximum of six months 23 and may be updated, replaced, or obsoleted by other documents at any 24 time. It is inappropriate to use Internet-Drafts as reference 25 material or to cite them other than as "work in progress." 27 The list of current Internet-Drafts can be accessed at 28 http://www.ietf.org/ietf/1id-abstracts.txt. 30 The list of Internet-Draft Shadow Directories can be accessed at 31 http://www.ietf.org/shadow.html. 33 This Internet-Draft will expire on October 30, 2008. 35 Copyright Notice 37 Copyright (C) The IETF Trust (2008). 39 Abstract 41 This document describes a new approach to handling user mobility at 42 the network layer in the context of Multi-Protocol Label Switched 43 Networks (MPLS). This approach does not rely on the existing IP 44 mobility management protocols such as Mobile IP, and is instead based 45 on the combination of Multi-Protocol BGP (MP-BGP) and MPLS. This 46 document proposes to introduce new protocol elements to MP-BGP to 47 achieve Mobility Label distribution at the network control plane and 48 the optimal packet delivery to the mobile node by the network 49 forwarding plane using MPLS. 51 Table of Contents 53 1. Requirements notation . . . . . . . . . . . . . . . . . . . . 4 54 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5 55 2.1. Architecture Requirements . . . . . . . . . . . . . . . . 6 56 2.2. Existing Solutions . . . . . . . . . . . . . . . . . . . . 6 57 2.2.1. Mobile IP . . . . . . . . . . . . . . . . . . . . . . 6 58 2.2.2. Mobile IPv6/HMIP/NEMO . . . . . . . . . . . . . . . . 7 59 2.2.3. MPLS Micro-Mobility . . . . . . . . . . . . . . . . . 7 60 2.3. Protocol Overview . . . . . . . . . . . . . . . . . . . . 8 61 2.4. Architecture Overview . . . . . . . . . . . . . . . . . . 8 62 2.4.1. Node Roles . . . . . . . . . . . . . . . . . . . . . . 9 63 2.4.2. Attachment Options . . . . . . . . . . . . . . . . . . 10 64 2.4.3. Network Hierarchy . . . . . . . . . . . . . . . . . . 13 65 2.4.4. Interface to Other Networks . . . . . . . . . . . . . 13 66 3. Mobility Support Function . . . . . . . . . . . . . . . . . . 15 67 3.1. Mobile Node Discovery, Registration and Status . . . . . . 15 68 3.1.1. Discovery Process - IPv4 . . . . . . . . . . . . . . . 15 69 3.1.1.1. MSF Discovery by Mobile Hosts - IPv4 . . . . . . . 17 70 3.1.1.2. MSF Discovery by Mobile Routers - IPv4 . . . . . . 18 71 3.1.1.3. MSF Advertisement - IPv4 . . . . . . . . . . . . . 18 72 3.1.2. Discovery Process - IPv6 . . . . . . . . . . . . . . . 20 73 3.1.2.1. MSF Discovery by Mobile Hosts - IPv6 . . . . . . . 22 74 3.1.2.2. MSF Discovery by Mobile Routers - IPv6 . . . . . . 22 75 3.1.2.3. MSF Advertisement - IPv6 . . . . . . . . . . . . . 22 76 3.1.3. Registration and Status - IPv4 . . . . . . . . . . . . 22 77 3.1.3.1. Mobile Host Registration - IPv4 . . . . . . . . . 22 78 3.1.3.1.1. Lightweight Registration - IPv4 . . . . . . . 22 79 3.1.3.1.2. Full Registration - IPv4 . . . . . . . . . . . 23 80 3.1.3.1.3. Group Registration - IPv4 . . . . . . . . . . 25 81 3.1.3.2. Mobile Router Registration - IPv4 . . . . . . . . 29 82 3.1.3.2.1. Routing Adjacency Establishment . . . . . . . 29 83 3.1.4. Registration and Status - IPv6 . . . . . . . . . . . . 30 84 3.2. Integration with MP-BGP . . . . . . . . . . . . . . . . . 30 85 3.2.1. Mobility Address Family . . . . . . . . . . . . . . . 30 86 3.2.2. Mobility Bindings . . . . . . . . . . . . . . . . . . 32 87 3.2.3. Group Registration Management with MP-BGP . . . . . . 35 88 3.2.4. BGP Capability Advertisement . . . . . . . . . . . . . 37 89 3.3. Mobile Application Priority Indication and Recognition . . 38 90 3.4. Application Service Type Indication . . . . . . . . . . . 38 91 4. Network Update and Hand-off Processing . . . . . . . . . . . . 40 92 4.1. Network Update Modes and Types . . . . . . . . . . . . . . 40 93 4.1.1. Unsolicited Downstream Push Mode . . . . . . . . . . . 40 94 4.1.2. Selective Downstream Push Mode . . . . . . . . . . . . 40 95 4.1.3. Predictive Downstream Push Mode . . . . . . . . . . . 40 96 4.1.4. Hierarchical On-Demand Distribution Mode . . . . . . . 41 97 4.1.4.1. On-Demand Requests for Mobility Binding 98 Information . . . . . . . . . . . . . . . . . . . 41 99 4.1.5. Network Update Types . . . . . . . . . . . . . . . . . 44 100 4.1.5.1. Internal Update Type . . . . . . . . . . . . . . . 44 101 4.1.5.2. External Update Type . . . . . . . . . . . . . . . 44 102 4.1.6. Network Hierarchy Considerations . . . . . . . . . . . 44 103 4.1.7. Regionalization and Scalability . . . . . . . . . . . 45 104 4.1.7.1. Hierarchical Mobility Label Based Network 105 (H-MLBN) . . . . . . . . . . . . . . . . . . . . . 46 106 4.2. Hand-off Processing . . . . . . . . . . . . . . . . . . . 47 107 4.3. Micro-Mobility Handling . . . . . . . . . . . . . . . . . 48 108 4.3.1. Local Micro-Mobility . . . . . . . . . . . . . . . . . 49 109 4.3.2. Group Micro-Mobility . . . . . . . . . . . . . . . . . 49 110 5. Datagram Delivery . . . . . . . . . . . . . . . . . . . . . . 50 111 6. Security Considerations . . . . . . . . . . . . . . . . . . . 51 112 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 52 113 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 53 114 9. Patent Issues . . . . . . . . . . . . . . . . . . . . . . . . 54 115 10. Changes from Previous Revisions . . . . . . . . . . . . . . . 55 116 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 56 117 11.1. Normative References . . . . . . . . . . . . . . . . . . . 56 118 11.2. Informative References . . . . . . . . . . . . . . . . . . 56 119 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 58 120 Intellectual Property and Copyright Statements . . . . . . . . . . 59 122 1. Requirements notation 124 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 125 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 126 document are to be interpreted as described in [RFC2119]. 128 2. Introduction 130 The requirements to support user mobility range from the physical 131 aspects of wireless access networks to the logical aspects of the 132 network control and forwarding plane operation. In the context of 133 this work the main requirement for the mobility support architecture 134 is to de-couple the network layer addressing and the associated 135 logical network topology from the ability of the network to optimally 136 deliver the packets to the mobile user. The optimal traffic delivery 137 is interpreted as the delivery of packets to the new node location 138 following the best (often the shortest in terms of the routing 139 protocol metrics) path between the mobile node and the correspondent 140 node. 142 The issue is that this optimal path cannot be used by the network to 143 communicate with the mobile user based on the IP address and routing 144 protocols. This is due to the inability of a conventional IP network 145 to react to the mobile user movements by adjusting the routing and 146 forwarding information in the network nodes (routers) to reflect the 147 new location of the mobile user with respect to the IP topology. 149 Thus a method is required to identify the logical location of the 150 user in the network topology in such a manner that the traffic 151 delivery to the user at a new location follows the optimal path in 152 the context of the routing protocol used in the network. A natural 153 fit to provide this method is the MPLS architecture. MPLS does not 154 perform the forwarding of IP traffic based on the IP addresses and 155 uses labels instead. The important point, however, is that MPLS by 156 itself cannot solve the mobility problem as ultimately the traffic 157 must originate from the source IP address and terminate at the 158 destination IP address (which would still be the old home address). 159 In order to use MPLS to forward the traffic to the new user location 160 along the optimal path the labels must be assigned specifically to 161 the mobile node at the new location and distributed to the network 162 nodes. These special labels are referred to as Mobility Labels and 163 are associated (bound) to the mobile node IP address. 165 This document proposes to use the Mobility Label as a second label in 166 the MPLS label stack. The first label in the stack is the one that 167 identifies the LSP (Label Switched Path) between the two Label Edge 168 Routers and the second label in the stack can be used to identify the 169 IP address of the mobile node and deliver the traffic to it. The 170 assignment and the distribution of the first label in the stack is 171 handled by the conventional MPLS architecture elements and protocols 172 such as LDP (Label Distribution Protocol [RFC5036]). It is proposed 173 that the assignment and distribution of the second label - the 174 Mobility Label - be based on the existing framework of MP-BGP (Multi- 175 Protocol Border Gateway Protocol [RFC4760]). The mobility management 176 scheme based on MP-BGP at the control plane level and MPLS at the 177 forwarding plane level represents a system in which both the control 178 and forwarding processes are integrated to ensure the optimal traffic 179 delivery that is not fully achieved in the existing network layer 180 mobility management approaches. 182 2.1. Architecture Requirements 184 Integrated Control and Forwarding Plane - the network update process 185 by the Control Plane must result in the optimal traffic delivery by 186 the Forwarding Plane. 188 Robust and Flexible Protocol Framework - Mobility Management Control 189 Plane Protocol and the associated functions must be placed at the 190 intelligent network edges and allow to avoid the need to involve all 191 nodes in the network (including the core nodes) in the network update 192 process. 194 Mobility Management Control Plane Protocol must allow for flexible 195 and seamless introduction of new features and for support for Mobile 196 Hosts and Mobile Routers. 198 Evolutionary Architecture and Implementation Approach - Mobility 199 Management scheme should be based as much as possible on the existing 200 network architectures and protocol framework. Only minimal changes 201 to the operation of mobile nodes should be expected. 203 Efficient Network Responsiveness - the impact on the mobile 204 application due to the service disruption caused by the mobile node's 205 movements and the associated network update and delivery processes 206 should be reasonably minimal. 208 Acceptable Network Scalability and Performance - the new requirements 209 for Mobility Management functions should not result in decreased 210 network scalability and performance. 212 2.2. Existing Solutions 214 2.2.1. Mobile IP 216 Mobile IP [RFC3344] was developed to provide macro mobility 217 management for the mobile hosts using IP version 4 (IPv4). It was 218 subsequently extended to support IPv6. Due to its complete reliance 219 on the logical network topology determined by the distribution of the 220 IP sub-nets Mobile IP solves the mobility problem by using the 221 following two major techniques: mobile node registration and traffic 222 tunneling. The main entities in Mobile IP are the Mobile Node (MN) 223 itself, the Correspondent Node (CN) - the host that is communicating 224 with the MN, the Home Agent (HA) - this is the router that owns the 225 original home sub-net to which the MN is assigned, the Foreign Agent 226 (FA) - this is the router that owns the sub-net to which the MN has 227 moved (the foreign sub-net), and finally the Care-of-Address (CoA) - 228 the IP address that belongs to the FA and that is used to represent 229 the MN while it is located in the foreign sub-net. The basic 230 mobility handling by Mobile IP results in a sub-optimal forwarding 231 path in the direction of traffic from the CN to the new location of 232 the MN. This is because the traffic is first sent to the HA and then 233 tunneled to the FA/MN. Although the route optimization scheme exists 234 where the mobility bindings are sent by the HA directly to the CN 235 with the CoA of the MN for direct traffic forwarding, it requires the 236 CN to i) implement the binding processing and ii) use IP tunneling to 237 send packets to the MN. 239 2.2.2. Mobile IPv6/HMIP/NEMO 241 Mobile IPv6 [RFC3775] provides macro-mobility support for IPv6. It 242 improves Mobile IPv4 by eliminating the need for the FA, use of the 243 IPv6 neighbor discovery instead of ARP, use of the IPv6 Link Local 244 (LLOC) address instead of CoA. It also provides basic support for 245 mobile routers via NEMO (Network Mobility) [RFC3963] and enables 246 hierarchical mobility management (HMIP). However MIPv6 does not 247 provide for the integration of the control and forwarding planes and 248 still requires the use of the HA which results in sub-optimal traffic 249 routing. The routing optimization based on the direct binding 250 exchange between the CN and the MN resolves the sub-optimal routing 251 but introduces the requirement for the return routability procedure 252 and the use of a special IPv6 routing header (similar in function to 253 IPv4 tunneling) directly on the CN and MN. In addition, Hierarchical 254 MIPv6 requires registrations to multiple entities (MAP - Mobility 255 Anchor Point, HA) and supports IPv6 only. 257 2.2.3. MPLS Micro-Mobility 259 MPLS Micro-Mobility [MM-MPLS] integrates MIP and MPLS traffic 260 forwarding to provide a solution in which MIP is used for macro 261 mobility management and MPLS is used to support micro-mobility. 262 Micro-mobility reflects the mobile host movements that can be handled 263 without the re-registration with the MIP HA. To achieve this, the MN 264 registers with a hierarchical set of Label Edge Mobility Agents 265 (LEMA). The LEMA at the top of the hierarchical set is registered 266 with the MIP HA as the FA for the MN. The MIP HA tunnels all packets 267 from the CN to the MN to the top level LEMA as in regular MIP. The 268 LEMA then sends packets on the MPLS LSP to the network location of 269 the MN using MPLS labels. As the MN moves to new locations, the 270 hand-off procedures are invoked that start with the MN requesting the 271 hand-off and the LEMA(s) performing the set of signaling steps 272 resulting in the redirection of the MPLS LSP from the old serving 273 LEMA to the new serving LEMA. If the MN movement results in a 274 condition in which the old top level LEMA can no longer serve the MN, 275 the MN re-registers with the new hierarchical set of LEMA(s) and the 276 top level LEMA is registered as the FA with the Mobile IP HA. 277 Although MPLS Micro-Mobility makes use of the MPLS traffic forwarding 278 it still is an extension of Mobile IP and therefore does not result 279 in the elimination of triangular routing. 281 2.3. Protocol Overview 283 MP-BGP and its ability to carry the overlay MPLS label information 284 [RFC3107] is proposed for the mobility management. Namely when the 285 mobile hosts or routers change their network locations they can 286 register with the edge nodes of the MPLS network (LER) and at that 287 time assigned Mobility Labels. The Mobility Labels in turn are 288 associated with the IP addresses of mobile hosts or routers thus 289 forming the Mobility Bindings. These Mobility Bindings are then 290 encoded in the Multi-Protocol BGP Address Family messaging structure 291 and are distributed among the rest of the MPLS network LER nodes 292 using the MP-BGP protocol. The Mobility Binding provides an explicit 293 association between the overlay MPLS label and a single or multiple 294 individual IP addresses of mobile hosts or IP address ranges 295 (prefixes) that are served by mobile routers. The MP-BGP NEXT_HOP 296 attribute associated with the BGP UPDATE message [RFC4271] used to 297 carry the Mobility Binding provides an implicit association between 298 the overlay Mobility Label and the infrastructure MPLS label that is 299 in turn associated with the LSP to reach the LER that sourced the 300 Mobility Binding. The MPLS LER capability to provide mobility 301 support can be referred to as the Mobility Support Function (MSF) 302 (see Section 3). The MSF includes: a) Mobile Host/Router Discovery, 303 Registration and Status Procedures, b) Mobility Label Association and 304 de-Association Procedures, c) Integration with MP- BGP and d) Mobile 305 Application Priority Indication and Recognition. Please see [MLBN]. 307 2.4. Architecture Overview 309 This mobility architecture is proposed in the context of MPLS 310 networks. As such it is a requirement of this architecture that all 311 nodes in the network support MPLS control and forwarding plane 312 procedures and in particular it is a further requirement that the 313 edge nodes of the MPLS network implement the Mobility Support 314 Function described in Section 3. This architecture does not rely on 315 Mobile IP for macro-mobility support. In other words there is no 316 concept of a home network that the mobile node belongs to and 317 therefore there is no requirement to register with the Home Agent. 318 It is the assumption of this architecture that a mobile host or 319 router is always identified as being in the foreign network thus 320 always requiring mobility support. In addition, there is no 321 requirement for the CoA. 323 The simplest way to implement this assumption is to administratively 324 allocate a range of IP addresses for all mobile hosts and routers of 325 an organization and to implement in the MSF the configurable ability 326 to recognize the pre-allocated mobility address ranges. As such, a 327 service provider would assign IP addresses to all of their mobile 328 subscribers from a pre-allocated address range. This range does not 329 have to be flat and can be in turn sub-netted. The IPv4 or IPv6 330 mobility address pre-allocation scheme allows utilization of this 331 mobility management architecture as a separate overlay MPLS service. 332 The only requirement related to the LER MSF pre-configuration is the 333 static identification of the overall mobility address range in the 334 scope of the LER-wide MSF. 336 Regardless of the static identification of the overall address range 337 allocated to the mobile devices, the individual mobile nodes identify 338 themselves dynamically to the MSF. This capability is especially 339 useful when this architecture is applied to provide mobility support 340 to both mobile hosts and routers. Specifically, during the 341 registration procedure a mobile node could identify itself as either 342 a mobile host or a mobile router. If it is a mobile router the MSF 343 is expected to establish a routing protocol adjacency with the mobile 344 router as well as to utilize an extended Mobility Binding structure 345 in which multiple IP prefixes served by the mobile router may be sent 346 in a single Mobility Binding optionally associated with a single 347 Mobility Label. 349 The mobile node must always register with the serving MSF and thus be 350 associated with the Mobility Label. This requirement will support 351 the ability to implement specific mobility features such as the 352 application sensitivity recognition via the processing prioritization 353 scheme. 355 2.4.1. Node Roles 357 From the network architecture perspective the proposed mobility 358 solution follows the classical MPLS network architecture with two 359 major node classes: LSR and LER also known as P and PE respectively. 360 The LER (PE) nodes reside at the edges of the network and perform the 361 corresponding edge functions such as the customer interface 362 management, label stack imposition/deposition and label information 363 distribution for both the infrastructure MPLS transport and the 364 overlay MPLS services. In addition to these edge functions we 365 introduce the Mobility Support Function that integrates directly with 366 the LER control plane responsible for the overlay MPLS services. The 367 role of the LSR (P) nodes remains exactly the same as in the 368 classical MPLS architecture - participate in the infrastructure label 369 distribution process and switch traffic based on the MPLS labels 370 (outer labels) between the LER nodes. The LSR (P) nodes need not 371 implement the MSF. Other aspects of the architecture include the 372 access interface, the interface to other networks and the network 373 hierarchy. 375 2.4.2. Attachment Options 377 The two major access interface options considered here are: Direct 378 Attachment of the LER node to the Radio Access Network and Indirect 379 Attachment of the LER node to the Radio Access Network. The terms 380 direct and indirect are not used to indicate that the LER node has or 381 does not have the integrated wireless radio interface. The term 382 direct is used to reflect that a direct layer 2 path exists between 383 the mobile node and the MSF enabled LER either via the integrated 384 radio interface or via the wire-line grooming network to the wire- 385 line side of the Radio Access Network Base Stations. The term 386 Indirect is used to reflect that there is no direct layer 2 path 387 between the Radio Access Network and the MSF enabled LER node. The 388 Indirect Attachment means that there is another layer 3 device (such 389 as the Customer Edge - CE router in the MPLS Architecture 390 terminology) between the MSF enabled LER and the Radio Access 391 Network. The CE router in turn connects to the Radio Network via 392 Direct Attachment (in the sense of the term defined here) by using 393 the integrated wireless interface or by using the wire-line grooming 394 network. The reason for establishing these two access options 395 relates to the type of service environments that the proposed 396 architecture will most likely be applicable to. 398 The Direct Attachment option is most suitable for the use case where 399 mobility is offered as an overlay service in a service provider's 400 mobility enabled MPLS network. In this case the Mobility Support 401 Function may be viewed as one of the functions in the MPLS for Mobile 402 Networks Architecture. An example of such a use case is the Wireless 403 Telephone service with data or multi-media capabilities (such as 404 EV-DO) in which mobility management is handled by the MSF enabled 405 MPLS network. The mobile nodes may be the wireless telephone sets 406 with IPv4 or IPv6 stacks and the corresponding mobility addresses 407 assigned by the service provider, communicating via the Radio Access 408 Network Base Stations to the MSF enabled LER nodes. A simple 409 registration procedure triggers the assignment of the overlay 410 Mobility Labels and the subsequent mobility management by MP-BGP. 412 The Indirect Attachment option is most suitable when the mobility 413 service is integrated with other overlay MPLS services such as Layer 414 3 VPN [RFC4364]. This use case is applicable for the enterprise 415 networking where the mobile nodes can be the wireless workstations or 416 wireless IP telephones, and the enterprise sites connecting to the 417 service provider's mobility enabled MPLS network via the CE routers. 418 The simplest way to accommodate the presence of the CE routers is to 419 implement the MSF function on the CE router and use the MP-BGP and 420 Mobility Labels between the CE router and the LER (PE) router in the 421 context of the customer specific MPLS VPN. This also implies the use 422 of MPLS and MP-BGP between the CE and PE routers for the delivery of 423 traffic to the mobile nodes behind the CE router, but since there 424 will be no LSR (P) routers between the MSF enabled CE and the PE 425 router there is actually no need for the outer stack MPLS labels and 426 therefore no need to integrate the CE routers with the service 427 provider's MPLS infrastructure. The MPLS LER (PE) router will need 428 to accept the Mobility Binding information via the use of MP-BGP from 429 the CE router within the MPLS VPN and then propagate that information 430 into the MPLS network using the L3 VPN MPLS overlay service also 431 based on MP-BGP. 433 The direct attachment option is shown in Fig.1, where a MSF enabled 434 LER node interfaces with multiple Radio Cells or Cell Clusters via 435 the L2 network such as Ethernet. Each Radio Cell Cluster is assigned 436 into a L2 Virtual LAN and associated with a L3 sub-net that is 437 terminated at a logical interface of the LER node. The logical 438 interfaces are controlled by the MSF and the associated set of Radio 439 Cells or Clusters forms a Mobility Region. 441 In Fig. 2 a similar arrangement is illustrated but in this case there 442 is no direct L2 path between the Radio Access Network and the MPLS 443 edge. A CE router provides the MSF and communicates the Mobility 444 Binding information by means of MP-BGP to the MPLS LER (PE) router. 446 +-----+ 447 |MSF ++-----------+ +------------+ 448 Radio Cell +----++ | | | 449 ,-----. | LER ........MPLS Network 450 / \ | | | | 451 / ((++)) \ +--+-+-++-+-++ +------------+ 452 ( || ) L3 Logical Interfaces 453 ,----+. +`-._/ / / / / / / 454 / \ /`-. +--+-+-+-+-+-++ 455 / ((++))`+----' `+._ / / /| /| .-----, 456 ( || ,-----. ___|___ / / / `-. / \ 457 \ ++--''''''''' | / | `-. |`. / ((++)) \ 458 \ // ((++)) \ |.-' `. `-. `-. || ) 459 `----(' || .-'+--------+----+`-.\ `-.+ .+----, 460 \ +_.-'/ L2 Network `+. / \ 461 \ / \ ``-.-+'((++)) \ 462 `-----' `. .----`-. || ) 463 Base Station \ / \\`-.+ / 464 `. ((++)) \\ / 465 ( \ || `)----' 466 \ `.++ / 467 \ / 468 `-----' 469 Base Station 471 Direct Attachment Option 473 Figure 1 475 +-----+ 476 |MSF ++-----------+ +-----------+ 477 Radio Cell +----++ | MP-BGP+| | 478 ,-----. | CE .......... MPLS LER | 479 / \ | |Mobility| | 480 / ((++)) \ +--+-+-++-+-++ +-----------+ 481 ( || ) L3 Logical Interfaces 482 ,----+. +`-._/ / / / / / / 483 / \ /`-. +--+-+-+-+-+-++ 484 / ((++))`+----' `+._ / / /| /| .-----, 485 ( || ,-----. ___|___ / / / `-. / \ 486 \ ++--''''''''' | / | `-. |`. / ((++)) \ 487 \ // ((++)) \ |.-' `. `-. `-. || ) 488 `----(' || .-'+--------+----+`-.\ `-.+ .+----, 489 \ +_.-'/ L2 Network `+. / \ 490 \ / \ ``-.-+'((++)) \ 491 `-----' `. .----`-. || ) 492 Base Station \ / \\`-.+ / 493 `. ((++)) \\ / 494 ( \ || `)----' 495 \ `.++ / 496 \ / 497 `-----' 498 Base Station 500 In-Direct Attachment Option 502 Figure 2 504 2.4.3. Network Hierarchy 506 The distribution of the Mobility Binding information using MP-BGP may 507 be achieved by constructing a flat or hierarchical MP-BGP peering 508 topology among the participating LER nodes. The flat peering logical 509 structure requires a full mesh of MP-BGP sessions and the 510 hierarchical peering structure can make use of the BGP Route 511 Reflectors in which some LER nodes are designated as the Route 512 Reflectors and establish peering sessions between themselves and all 513 other LER supporting MSF (Route-Reflector-Clients). The BGP Route 514 Reflectors capable of supporting MPLS Mobility are referred to as 515 Mobility Route Reflectors. It is important to note that the Mobility 516 Route Reflectors need not support the MSF but must be able to 517 interpret and relay the MSF related MP-BGP messaging. 519 2.4.4. Interface to Other Networks 521 The interface to other networks depends on how the mobility is to be 522 managed between the interconnecting networks. If all mobility 523 functions are to be managed by a service provider's network (given 524 that the network has sufficient coverage) then the interface to other 525 networks can be as simple as the peering gateway node that connects 526 the service provider's MPLS network to the rest of the world. In 527 this case there is no need to extend the MPLS processing over this 528 interface, and since by construction all mobility IP addresses belong 529 to the IP address space of the service provider, the general peering 530 arrangement to other networks where the IP address range of the 531 service provider is advertised out to the Internet will enable the 532 communication between the mobile nodes and the outside destinations. 533 In case of the mobile node roaming, this may be supported between the 534 service provider networks that both implement the customer facing 535 Mobility Support Function and the Network-to-Network Interface (NNI) 536 that employs the use of MPLS label exchange (including the Mobility 537 Labels). 539 3. Mobility Support Function 541 This section describes the proposed set of functional elements of the 542 MPLS LER node capable of providing mobility management services. 543 This document refers to these functional elements as a Mobility 544 Support Function (MSF). 546 3.1. Mobile Node Discovery, Registration and Status 548 3.1.1. Discovery Process - IPv4 550 As in [RFC3344] the discovery of the MSF by the mobile nodes is based 551 on the ICMP Router Discovery [RFC1256] with specific extensions for 552 Mobility Label Based Network (MLBN). The format of the extensions 553 used in this proposal also follows the [RFC3344] section 1.9. 555 The discovery process should be initiated by a mobile host or router 556 by sending the ICMP Router Solicitation message with MLBN MSF 557 Discovery Extension and the TTL set to 1. This ICMP message along 558 with the MLBN Extension is referred to as the MSF Discovery message. 559 The MSF Discovery message should carry the information about the type 560 of the mobile node: Mobile Host or Mobile Router. 562 Upon receipt of the MSF Discovery message the MSF LER must respond 563 with the ICMP Router Advertisement including the MLBN specific 564 Extension. This message is referred to as the MSF Advertisement. 565 The MSF Advertisement will carry different information depending on 566 the type of the mobile node and the registration mode. 568 0 1 2 3 569 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 570 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 571 | Type | Code | Checksum | 572 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 573 | Reserved | 574 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 575 | MSF Discovery Extension TLV (variable) | 576 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 578 ICMP Router Solicitation with MSF Discovery Extension 580 Figure 3 582 Link Layer Fields: Destination Address - This should be the 583 multicast or broadcast Link Layer Address. 585 IP Fields: Source Address - IP Address of the Mobile Host or IP 586 address of the interface of the Mobile Router from which this 587 message is sent. 589 Destination Address - This is the all-routers multicast address 590 224.0.0.2 or the limited broadcast address 255.255.255.255. 592 TTL - TTL should be set to 1. 594 ICMP Fields: Type = 10 Router Solicitation. 596 Code = 1 MLBN MSF Discovery Extension included. 598 0 1 2 3 599 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 600 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 601 | Type | Code | Checksum | 602 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 603 | Num Addrs |Addr Entry Size| Lifetime | 604 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 605 | Router Address[1] | 606 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 607 | Preference Level[1] | 608 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 609 | MSF Advertisement Extension (variable) | 610 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 612 ICMP Router Advertisement with MSF Advertisement Extension 614 Figure 4 616 Link Layer Fields: Destination Address - This should be the source 617 address used to deliver the MSF Discovery message from the mobile 618 node. 620 IP Fields: Source Address - IP Address of the MSF. 622 Destination Address - This is the unicast IP address used in the 623 IP header of the MSF Discovery message from the mobile node. 625 TTL - TTL should be set to 1. 627 ICMP Fields: Type = 9 Router Advertisement. 629 Code = 1 MLBN MSF Advertisement Extension included. 631 Please refer to [RFC1256] for the specification of the remaining 632 fields in both of the above messages. 634 3.1.1.1. MSF Discovery by Mobile Hosts - IPv4 636 Mobile hosts should initiate the MSF Discovery process by sending the 637 MSF Discovery message. The MSF Discovery Extension format for Mobile 638 Hosts is shown below. 640 0 1 2 3 641 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 642 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 643 | Type | Length |H|Pri. |L|ASTI | Area_ID | 644 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 645 | Mobile Host IPv4 Source Address | 646 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 647 | Correlation ID | 648 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 650 Mobile Host MSF Discovery Extension for IPv4 652 Figure 5 654 Type - 0 = MSF Discovery 656 Length - Length of the message in octets. 658 H - Mobile Node Type Indication. 0 = Mobile Host. 660 Pri. - A 3-bit Priority Code (0-7). 662 L - Lightweight Registration Requested (1). 664 ASTI - Application Service Type Indication. This 3-bit field may 665 be used to indicate to the MSF what type of service is to be used 666 by the mobile host. For example, "Internet Access Only" or Full 667 Mobile-to-Mobile Routing". This indication can then be mapped to 668 the Network Update Mode Code used in the Mobility Binding 669 structure. 671 Area_ID - An Identifier (1-255) associated with the Area Mobility 672 Route Reflector. Area_ID=0 must be used for initial registrations 673 by mobile nodes. 675 Correlation ID - a number used to keep track of the Lightweight 676 Registration message pairs - MSF Discovery/MSF Advertisement. 678 3.1.1.2. MSF Discovery by Mobile Routers - IPv4 680 Mobile routers should initiate the MSF Discovery process by sending 681 the MSF Discovery message. The MSF Discovery Extension format for 682 Mobile Routers is shown below. 684 0 1 2 3 685 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 686 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 687 | Type | Length |R|Pri. |L|Res. | Area_ID | 688 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 689 | Mobile IPv4 Router-ID | 690 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 692 Mobile Router MSF Discovery Extension 694 Figure 6 696 Type - 0 = MSF Discovery 698 Length - Length of the message in octets. 700 R - Mobile Node Type Indication. 1 = Mobile Router. 702 Pri. - A 3-bit Priority Code (0-7). 704 L - Always set to 0 in the MSF Discovery sent by a mobile router. 706 Res. - Reserved. 708 Area_ID - An Identifier (1-255) associated with the Area Mobility 709 Route Reflector. Area_ID=0 must be used for initial registrations 710 by mobile nodes. 712 3.1.1.3. MSF Advertisement - IPv4 714 After receiving the MSF Discovery message from a mobile host or 715 router the MSF should reply with the MSF Advertisement message using 716 extension format shown below. 718 0 1 2 3 719 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 720 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 721 | Type | Length | Sequence Number | 722 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 723 | Registration Lifetime |L|R|G|Reserved | Group ID | 724 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 725 | MSF IP Address | 726 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 727 | MSF Virtual Link Layer Address (first 32 bits) | 728 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 729 |Last 16 bits | Reserved | Area_ID | 730 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 731 | Correlation ID | 732 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 734 MSF Advertisement Extension 736 Figure 7 738 Type - 1 = MSF Advertisement 740 Length - Length of the message in octets. 742 Sequence Number - The sequence number of the MSF Advertisement 743 message sent since the MSF is operational. 745 Registration Lifetime - the time in seconds until the registration 746 entry in the MSF database expires. 748 L - Lightweight Registration Confirmed (1). 750 R - Full Registration Required (1). 752 G - Group Registration Supported (1). 754 Group ID - Unique Registration Group Number. Should be zero if G 755 = 0 757 MSF IP Address - Virtual IP Address of the MSF (may be different 758 from any particular MSF LER interface IP address 760 MSF Virtual Link Layer Address - a MAC address shared and 761 recognized by all MPLS LER interfaces participating in the MSF. 762 This address may specifically be used to support Local Micro- 763 Mobility (see Section 4.3.1). 765 Area_ID - An Identifier (1-255) associated with the Area Mobility 766 Route Reflector. Area_ID=0 must be used for initial registrations 767 by mobile nodes. 769 Correlation ID - a number used to keep track of the registration 770 requests and the corresponding reply message pairs. 772 The MSF Advertisement should be sent to the unicast link layer 773 address and the unicast IP address of the mobile host or router that 774 were used in the MSF Discovery link layer header and the MSF 775 Discovery Extension payload respectively. 777 Upon receipt of the MSF Advertisement mobile hosts should continue to 778 send the MSF Discovery messages with the interval of 1/3 of the 779 specified Registration Lifetime. The MSF should send the MSF 780 Advertisements in response to the periodic MSF Discovery messages 781 from the mobile hosts using the corresponding Correlation IDs. If a 782 mobile host does not get responses to three MSF Discovery messages 783 (serving as the keepalives) the mobile host should initiate a new MSF 784 Discovery process using a new Correlation ID. 786 If the L flag in the MSF Advertisement is set, and the R flag is not, 787 indicating the Lightweight Registration mode (see Section 3.1.3.1), 788 the mobile hosts may start sending datagrams to their IP destinations 789 using the link layer address of the MSF. The L and R flags are 790 mutually exclusive and cannot be set at the same time. 792 If the R flag is set in the MSF Advertisement, indicating that 793 explicit registration is required, mobile hosts should transition to 794 the Full Registration mode (see Section 3.1.3.1.2). 796 The R flag must always be set in the MSF Advertisement if it is in 797 reply to the MSF Discovery sent by a mobile router. Upon receipt of 798 the MSF Advertisement a mobile router must transition to the Routing 799 Adjacency Establishment mode (see Section 3.1.3.2). 801 3.1.2. Discovery Process - IPv6 803 The MSF discovery process for IPv6 is identical to the discovery 804 process for IPv4 with the exception of the use of IPv6 specific 805 Router Solicitation and Advertisement messages based on ICMPv6 806 [RFC4443]. These messages are specified in [RFC4861]. As in the 807 IPv4 case the Router Solicitation and Advertisement messages carry 808 the MLBN extensions and are termed the MSF Discovery and the MSF 809 Advertisement respectively. 811 0 1 2 3 812 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 813 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 814 | Type | Code | Checksum | 815 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 816 | Reserved | 817 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 818 | MSF Discovery Extension TLV (variable) | 819 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 821 IPv6 Router Solicitation with MSF Discovery Extension 823 Figure 8 825 Link Layer Fields: Destination Address - This should be the 826 multicast or broadcast Link Layer Address. 828 IP Fields: Source Address - IP Address of the Mobile Host or IP 829 address of the interface of the Mobile Router from which this 830 message is sent. 832 Destination Address - This is the all-routers multicast address 833 FF02::2 835 ICMP Fields: Type = 133 Router Solicitation. 837 Code = 1 MLBN MSF Discovery Extension included. 839 0 1 2 3 840 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 841 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 842 | Type | Code | Checksum | 843 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 844 | Cur Hop Limit |M|O| Reserved | Router Lifetime | 845 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 846 | Reachable Time | 847 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 848 | Retrans Timer | 849 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 850 | MSF Discovery Extension TLV (variable) | 851 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 853 IPv6 Router Advertisement with MSF Advertisement Extension 855 Figure 9 857 Link Layer Fields: Destination Address - This should be the source 858 address used to deliver the MSF Discovery message from the mobile 859 node. 861 IP Fields: Source Address - IP Address of the MSF. 863 Destination Address - This is the unicast IP address used in the 864 IP header of the MSF Discovery message from the mobile node. 866 ICMP Fields: Type = 134 Router Advertisement. 868 Code = 1 MLBN MSF Advertisement Extension included. 870 Please refer to [RFC4861] for the specification of the remaining 871 fields in both of the above messages. 873 3.1.2.1. MSF Discovery by Mobile Hosts - IPv6 875 The MSF Discovery message format for IPv6 mobile hosts is identical 876 to the IPv4 message with the IPv6 Source Address used instead of the 877 IPv4 (see Section 3.1.1.1). 879 3.1.2.2. MSF Discovery by Mobile Routers - IPv6 881 The MSF Discovery message format for IPv6 mobile routers is identical 882 to the IPv4 message with the IPv6 Router ID used instead of the IPv4 883 (see Section 3.1.1.2). 885 3.1.2.3. MSF Advertisement - IPv6 887 The MSF Advertisement message format for IPv6 is identical to the 888 IPv4 message format (see Section 3.1.1.3). 890 3.1.3. Registration and Status - IPv4 892 3.1.3.1. Mobile Host Registration - IPv4 894 3.1.3.1.1. Lightweight Registration - IPv4 896 MLBN eliminates the need for the registrations with the Home Agent 897 and Care-of-Addresses. This makes it possible to implement a 898 Lightweight Registration procedure which is simply the completion of 899 the MSF Discovery process (Section 3.1.1). The Lightweight 900 Registration is indicated by the presence of the L flag in the MSF 901 Advertisement message. With the Lightweight Registration the MSF 902 should allocate the local Mobility Label and create the Mobility 903 Binding structure (Section 3.2.2) immediately following the receipt 904 of the MSF Discovery message from a mobile host. The MSF should also 905 initiate the network update process (see Section 4) based on the 906 selected update mode and the indicated mobile application priority. 908 The network update mode selection may be based on the Application 909 Service Type Indication (ASTI) from the MSF discovery message sent by 910 the mobile host. ASTI is a 3-bit field that may be used to indicate 911 to the MSF what type of service is to be used by the mobile host. 912 For example, "Internet Access Only" or "Full Mobile-to-Mobile 913 Routing". This indication can then be mapped to the Network Update 914 Mode Code used in the Mobility Binding structure. 916 3.1.3.1.2. Full Registration - IPv4 918 Full Registration is a registration mode which allows to perform 919 additional functions as part of the registration process. An example 920 of such function is the Mobile Host Authentication. Full 921 registration mode is indicated in the MSF Advertisement by setting 922 the R flag. 924 Full Registration messaging makes use of the UDP port RRR and may 925 provide a mechanism for various functional extensions. Full 926 Registration uses two message types: 928 Registration Request - Type 1 930 Registration Reply - Type 2 932 The Registration Message formats are shown below. 934 0 1 2 3 935 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 936 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 937 | Type | Length |H| Rri.|ASTI | Area_ID | 938 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 939 | Mobile Host IPv4 Source Address | 940 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 941 | MSF Address | 942 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 943 | Correlation ID | 944 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 945 | Extensions 946 +-+-+-+-+-+-+.... 948 Full Registration Request 950 Figure 10 952 Type - 1 = Full Registration Request 954 Length - Length of the message in octets. 956 H - Mobile Node Type Indication. 0 = Mobile Host 958 Pri. - A 3-bit priority code (0-7). 960 ASTI - Application Service Type Indication. This 3-bit field may 961 be used to indicate to the MSF what type of service is to be used 962 by the mobile host. For example, "Internet Access Only" or Full 963 Mobile-to-Mobile Routing". This indication can then be mapped to 964 the Network Update Mode Code used in the Mobility Binding 965 structure. 967 Area_ID - An Identifier (1-255) associated with the Area Mobility 968 Route Reflector. Area_ID=0 must be used for initial registrations 969 by mobile nodes. 971 Correlation ID - a number used to keep track of the registration 972 requests and the corresponding reply message pairs. 974 0 1 2 3 975 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 976 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 977 | Type | Length | Flags | 978 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 979 | Registration Lifetime | Reserved | Area_ID | 980 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 981 | Mobile Host IPv4 Source Address | 982 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 983 | MSF IP Address | 984 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 985 | MSF Virtual Link Layer Address (first 32 bits) | 986 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 987 |Last 16 bits | Reserved | 988 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 989 | Correlation ID | 990 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 991 | Extensions 992 +-+-+-+-+-+-+.... 994 Full Registration Reply 996 Figure 11 998 Type - 2 = Full Registration Reply 1000 Length - Length of the message in octets. 1002 Flags - To be defined 1004 Registration Lifetime - the time in seconds until the registration 1005 entry in the MSF database expires. 1007 Area_ID - An Identifier (1-255) associated with the Area Mobility 1008 Route Reflector. Area_ID=0 must be used for initial registrations 1009 by mobile nodes. 1011 MSF IP Address - Virtual IP Address of the MSF (may be different 1012 from any particular MSF LER interface IP address 1014 MSF Virtual Link Layer Address - a MAC address shared and 1015 recognized by all MPLS LER interfaces participating in the MSF. 1016 This address may specifically be used to support Local Micro- 1017 Mobility (see Section 4.3.1). 1019 Correlation ID - a number used to keep track of the registration 1020 requests and the corresponding reply message pairs. 1022 3.1.3.1.3. Group Registration - IPv4 1024 Clearly the discovery and registration procedure has a great effect 1025 on the network responsiveness especially when a mobile host moves 1026 from one serving MSF to another. The following enhanced registration 1027 scheme can be implemented to simplify the registrations resulting 1028 from the MSF-to-MSF hand-off and therefore improve the network 1029 responsiveness. We refer to it as the Group Registration. 1031 The entire MPLS edge network may be divided in groups or regions 1032 containing the geographically close MSF enabled LER nodes. Each 1033 group should be assigned a unique Group ID (1-255). The mobile host 1034 will register with a LER node within a group using a Group 1035 Registration procedure. The LER node will distribute the 1036 registration information to the rest of the group members using the 1037 established MP-BGP peering sessions. These messages may be coded as 1038 another type of the NLRI in the Address Family structure. The size 1039 of the region should be large enough to ensure a high probability 1040 that the range of movements of a mobile host will be covered by the 1041 service area of the group but at the same time not too large to avoid 1042 a large registration table size shared among the group members. The 1043 group members can be identified administratively and preconfigured in 1044 the MSF serving LER nodes. 1046 During the initial registration process and as part of the 1047 registration acknowledgement the serving LER may indicate to the 1048 mobile host that it is registered to a group and from now on should 1049 use a group virtual link layer address and a group virtual IP address 1050 for further communications (the addresses may be communicated in the 1051 acknowledgement payload). 1053 The group registration allows to implement the implicit logic by 1054 which no further registrations are required from the mobile node due 1055 to its movements once the initial group registration has been 1056 established. The group members may also pre-allocate the Mobility 1057 Labels and have them ready in case the mobile node moves into the 1058 member's serving area. Once the mobile node has moved into the 1059 serving area of the new MSF group member it continues to send packets 1060 to the group virtual link layer address and the virtual IP address. 1061 As soon as the packet from the mobile node is received by the group 1062 member it will forward the packet to its destination and distribute 1063 the new Mobility Binding to the network. A mobile host should 1064 continue to send the MSF Discovery messages destined to the group 1065 link layer address in order to keep the group registration active. 1067 The group member that is servicing the mobile host can periodically 1068 send the registration update messages to the group members in order 1069 to keep the Mobility Bindings in the standby status. If a group 1070 member has not received any keepalives or packets from the mobile 1071 host in a specified period of time it should silently deactivate its 1072 local registration entry and release the Mobility Label. If the 1073 mobile host happens to be serviced by another group member, this 1074 member will be sending the registration update messages to the group 1075 keeping the registration active. If no group member hears from the 1076 mobile node, the registration must be removed from the group database 1077 after a specified time and the associated Mobility Binding may be 1078 withdrawn from the network by means of the MP-BGP update. 1080 Group Registration message formats are very similar to the Full 1081 Registration message formats. The Group Registrations starts with 1082 the mobile host sending the MSF Discovery message and the MSF 1083 replying with the MSF Advertisement having the G flag set, indicating 1084 that the Group Registration is supported. After this the mobile host 1085 must transition to the Group Registration protocol using the same UDP 1086 port RRR as for the Full Registration. 1088 Group Registration uses two message types: 1090 Group Registration Request - Type 3 1091 Group Registration Reply - Type 4 1093 The Group Registration Message formats are shown below. 1095 0 1 2 3 1096 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1097 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1098 | Type | Length |H| Rri.|ASTI |G| Group ID | 1099 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1100 | Mobile Host IPv4 Source Address | 1101 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1102 | MSF Address | 1103 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1104 | Correlation ID | 1105 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1106 | Area_ID | Extensions 1107 +-+-+-+-+-+-+-+-+-+-+-+-+-+.... 1109 Group Registration Request 1111 Figure 12 1113 Type - 3 = Group Registration Request 1115 Length - Length of the message in octets. 1117 H - Mobile Node Type Indication. 0 = Mobile Host 1119 Pri. - A 3-bit priority code (0-7). 1121 ASTI - Application Service Type Indication. This 3-bit field may 1122 be used to indicate to the MSF what type of service is to be used 1123 by the mobile host. For example, "Internet Access Only" or Full 1124 Mobile-to-Mobile Routing". This indication can then be mapped to 1125 the Network Update Mode Code used in the Mobility Binding 1126 structure. 1128 G - Group Registration Requested (1) 1130 Group ID - Unique Registration Group Number. Should be zero if G 1131 = 0 1133 Correlation ID - a number used to keep track of the registration 1134 requests and the corresponding reply message pairs. 1136 Area_ID - An Identifier (1-255) associated with the Area Mobility 1137 Route Reflector. Area_ID=0 must be used for initial registrations 1138 by mobile nodes. 1140 0 1 2 3 1141 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1142 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1143 | Type | Length | Flags | 1144 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1145 | Registration Lifetime |G| Reserved | Group ID | 1146 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1147 | Mobile Host IPv4 Source Address | 1148 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1149 | Group Virtual IP Address | 1150 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1151 | Group Virtual Link Layer Address (first 32 bits) | 1152 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1153 |Last 16 bits | Reserved | 1154 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1155 | Correlation ID | 1156 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1157 | Area_ID | Extensions 1158 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+.... 1160 Group Registration Reply 1162 Figure 13 1164 Type - 4 = Group Registration Reply 1166 Length - Length of the message in octets. 1168 Flags - To be defined 1170 Registration Lifetime - the time in seconds until the registration 1171 entry in the MSF database expires. 1173 G - Group Registration Supported (1). 1175 Group ID - Unique Registration Group Number. Should be zero if G 1176 = 0 1178 Group Virtual IP Address - Virtual IP Address that is supported by 1179 all MSF's that belong to the Registration Group identified by the 1180 Group ID. This address may specifically be used to support Group 1181 Micro-Mobility (see Section 4.3.2). 1183 Group Virtual Link Layer Address - a MAC address shared and 1184 recognized by all MPLS LER interfaces of all MSF's that belong to 1185 the Registration Group identified by the Group ID. This address 1186 may specifically be used to support Group Micro-Mobility (see 1187 Section 4.3.2). 1189 Correlation ID - a number used to keep track of the registration 1190 requests and the corresponding reply message pairs. 1192 Area_ID - An Identifier (1-255) associated with the Area Mobility 1193 Route Reflector. Area_ID=0 must be used for initial registrations 1194 by mobile nodes. 1196 As in the Full Registration case the Group Registration allows to 1197 perform additional functions as part of the registration process by 1198 means of using the functional extensions. An example of such a 1199 function is the Mobile Host Authentication. 1201 After the completion of the Group Registration with the initial MSF 1202 that is part of the Registration Group, the mobile host must send the 1203 MSF Discovery messages destined to the Group Virtual Link Layer 1204 Address listing the Group ID and the Group Virtual IP Address. The 1205 registration information is communicated among the group members 1206 using MP-BGP signaling with the specific SAFI value assigned for this 1207 purpose (see Section 3.2.3). Any group member receiving the MSF 1208 Discovery messages from a mobile host for which the group 1209 registration is active must reply with the MSF Advertisement messages 1210 to the mobile host. When a mobile host moves from one group member 1211 to another it should continue to send packets to its IP destination 1212 using the Group Virtual Link Layer Address. 1214 3.1.3.2. Mobile Router Registration - IPv4 1216 Mobile routers should initiate the registration procedure by sending 1217 the registration message with the mobile router identification flag 1218 set and its Router ID (an IP address that belongs to the router) 1219 specified (see Section 3.1.1.2). 1221 Upon receipt of this registration information the MSF should initiate 1222 the establishment of the dynamic routing protocol adjacency with the 1223 mobile router using protocols such as BGPv4 [RFC4271]. The mobile 1224 router should advertise to the MSF the IP prefixes it serves using 1225 the established routing adjacency. 1227 3.1.3.2.1. Routing Adjacency Establishment 1229 The MSF should receive the routing protocol update from the mobile 1230 router and allocate a single Mobility Label to represent all of the 1231 served prefixes. This label should then be used in the Mobility 1232 Binding structure exported to the network by MP-BGP (see Figure 18). 1233 Optionally, each served IP prefix advertised by the mobile router can 1234 be associated with a separate Mobility Label. This can be used to 1235 provide different mobility processing priority to different IP 1236 prefixes. 1238 The mobile router status detection can be based on the state of the 1239 dynamic routing protocol adjacency maintained by the periodic 1240 keepalive messaging common to the routing protocols. 1242 3.1.4. Registration and Status - IPv6 1244 The registration procedures described for IPv4 in Section 3.1.3 are 1245 fully extended to IPv6 using the same message formats and the UDP 1246 port number. In all messages the IPv4 addresses are replaced with 1247 their IPv6 equivalents (with the corresponding increase in the 1248 required field length). 1250 Thus, for mobile hosts the Lightweight, Full and Group Registration 1251 modes are supported (see Section 3.1.3.1.1, Section 3.1.3.1.2, 1252 Section 3.1.3.1.3), and for mobile routers the same IPv4 procedure 1253 described in Section 3.1.3.2 and modified to include the IPv6 1254 messages should be supported. 1256 In addition to the use of the MSF Discovery/Advertisement message as 1257 keepalives for determining the status of the reachability of the 1258 serving MSF function, mobile nodes may utilize IPv6 Neighbor 1259 Unreachability Detection procedures specified in [RFC4861] section 1260 7.3. 1262 3.2. Integration with MP-BGP 1264 In order to integrate the MSF on the LER with the MP-BGP processing, 1265 a new Address Family must be created. This Address Family must be 1266 assigned a new and unique AFI following the Address Family structure 1267 of MP-BGP. This Address Family may be referred to as the Mobility 1268 Address Family. In fact a number of Mobility Address Families may be 1269 created to support IPv4/IPv6 unicast/multicast protocols. In all 1270 cases the Address Families must use the structure that allows them to 1271 carry the overlay MPLS label information (a specially designated 1272 value of SAFI). 1274 3.2.1. Mobility Address Family 1276 In order to carry the Mobility Binding information the BGP UPDATE 1277 message with the MP_REACH_NLRI and MP_UNREACH_NLRI optional non- 1278 transitive attributes is used as specified in [RFC4760]. 1280 For the mobility management purposes a set of new Address Family 1281 Identifiers (AFI) and Subsequent Address Family Identifiers (SAFI) 1282 are defined. Specifically the following new AFI values are defined: 1284 Mobility IPv4 Unicast - AFI X1 SAFI Y1 1286 Mobility IPv6 Unicast - AFI X2 SAFI Y1 1288 The MP_REACH_NLRI attribute is used to update the LER nodes with new 1289 Mobility Binding information. The structure of the attribute is 1290 shown below. 1292 +---------------------------------------------------------+ 1293 | Address Family Identifier (2 octets) | 1294 +---------------------------------------------------------+ 1295 | Subsequent Address Family Identifier (1 octet) | 1296 +---------------------------------------------------------+ 1297 | Length of Next Hop Network Address (1 octet) | 1298 +---------------------------------------------------------+ 1299 | Network Address of Next Hop (variable) | 1300 +---------------------------------------------------------+ 1301 | Reserved (1 octet) | 1302 +---------------------------------------------------------+ 1303 | Mobility Binding (NLRI) Information (variable) | 1304 +---------------------------------------------------------+ 1306 MP_REACH_NLRI with Mobility Binding 1308 Figure 14 1310 The MP_UNREACH_NLRI attribute is used to withdraw the Mobility 1311 Binding information. The structure of the attribute is shown below. 1313 +---------------------------------------------------------+ 1314 | Address Family Identifier (2 octets) | 1315 +---------------------------------------------------------+ 1316 | Subsequent Address Family Identifier (1 octet) | 1317 +---------------------------------------------------------+ 1318 | Mobility Binding (Withdrawn Routes) (variable) | 1319 +---------------------------------------------------------+ 1321 MP_UNREACH_NLRI with Mobility Binding 1323 Figure 15 1325 The Mobility Binding itself is encoded in the NLRI format shown 1326 below. 1328 +---------------------------+ 1329 | Length (1 octet) | 1330 +---------------------------+ 1331 |Mobility Binding (variable)| 1332 +---------------------------+ 1334 NLRI Encoding for Mobility Bindings 1336 Figure 16 1338 For the definitions of the fields in the above figures (with the 1339 exception of the Mobility Binding related information) please see 1340 [RFC4760]. 1342 3.2.2. Mobility Bindings 1344 Two types of Mobility Binding formats are proposed: Host Mobility 1345 Binding and Router Mobility Binding. 1347 0 1 2 3 1348 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1349 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1350 | Origin MP-BGP NEXT_HOP | 1351 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1352 | Target MP-BGP NEXT_HOP | 1353 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1354 | Mobile Host Address | 1355 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1356 |H| UM | UT | Mobility Label |Pri. |S| 1357 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1358 | Area_ID | 1359 +-+-+-+-+-+-+-+-+ 1361 NLRI Encoding for the Host Mobility Binding 1363 Figure 17 1365 Origin MP-BGP NEXT_HOP - Router ID of the MPLS LER originating the 1366 Mobility Binding. This address may be carried in the IPv4 or IPv6 1367 format depending on the {AFI, SAFI} pair used. 1369 Target MP-BGP NEXT_HOP - Router ID of the MPLS LER to receive the 1370 Mobility Binding using Selective Downstream Push. For the 1371 Unsolicited Downstream Push this field should be set to 0. This 1372 address may be carried in the IPv4 or IPv6 format depending on the 1373 {AFI, SAFI} pair used. 1375 Mobile Host Address - IPv4 or IPv6 Address of the mobile host. 1376 This address may be carried in the IPv4 or IPv6 format depending 1377 on the {AFI, SAFI} pair used. 1379 H - Mobile Node Type Indication. 0 = Mobile Host 1381 UM - Update Mode. This 3-bit code is mapped to the ASTI code in 1382 the MSF Discovery and Registration Request messages to indicate 1383 the Network Update Mode selection (see Section 4). 1385 UT - Update Type. This 4-bit code is used to indicate the 1386 Mobility Update Type (internal, external, inter-carrier - see 1387 Section 4). 1389 Mobility Label - Overlay MPLS Label (20 bits) associated with the 1390 IP address of the mobile host in the MSF database. 1392 Pri. - A 3-bit priority code (0-7). 1394 S - Bottom of Stack. 1396 Area_ID - An Identifier (1-255) associated with the Area Mobility 1397 Route Reflector. 1399 0 1 2 3 1400 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1401 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1402 | Origin MP-BGP NEXT_HOP | 1403 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1404 | Target MP-BGP NEXT_HOP | 1405 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1406 | Mobile Router ID | 1407 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1408 |R| UM | UT |No of Prefixes | IP Prefix 1 | 1409 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1410 | IP Prefix 1 | Prefix 1 Len. | Variable No. | 1411 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1412 | of Prefixes/Len | 1413 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1414 | Mobility Label |Pri. |S| Area_ID | 1415 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1417 NLRI Encoding for the Router Mobility Binding 1419 Figure 18 1421 Origin MP-BGP NEXT_HOP - Router ID of the MPLS LER originating the 1422 Mobility Binding. This address may be carried in the IPv4 or IPv6 1423 format depending on the {AFI, SAFI} pair used. 1425 Target MP-BGP NEXT_HOP - Router ID of the MPLS LER to receive the 1426 Mobility Binding using Selective Downstream Push. For the 1427 Unsolicited Downstream Push this field should be set to 0. This 1428 address may be carried in the IPv4 or IPv6 format depending on the 1429 {AFI, SAFI} pair used. 1431 Mobile Router ID - IP Address of the mobile router. This address 1432 may be carried in the IPv4 or IPv6 format depending on the {AFI, 1433 SAFI} pair used. 1435 R - Mobile Node Type Indication. 1 = Mobile Router 1437 UM - Update Type. This 3-bit code is mapped to the ASTI code in 1438 the MSF Discovery and Registration Request messages to indicate 1439 the Network Update Mode selection (see Section 4). 1441 UT - Update Type. This 4-bit code is used to indicate the 1442 Mobility Update Type (internal, external, inter-carrier - see 1443 Section 4). 1445 No. of Prefixes - Number of IP Prefixes carried in this Mobility 1446 Binding. 1448 IP Prefix 1 - First IP Prefix (32 bits for IPv4, 128 bits for 1449 IPv6) 1451 Prefix 1 Len. - Length (in number of bits) of the network part of 1452 IP Prefix 1 1454 Mobility Label - Overlay MPLS Label (20 bits) associated with each 1455 of the IP Prefixes served by the mobile router in the MSF database 1456 of the originating LER. 1458 S - Bottom of Stack. 1460 Area_ID - An Identifier (1-255) associated with the Area Mobility 1461 Route Reflector. 1463 The receiving MSF must read the R flag in the Mobility Binding and 1464 associate the provided Mobility Label with each of the IP prefixes 1465 found in the body of the Mobility Binding. The derived associations 1466 must be installed in the MPLS forwarding table of the MPLS LER and in 1467 turn associated with the infrastructure label assigned to the "Origin 1468 MP-BGP NEXT_HOP" address indicated in the received Mobility Binding 1470 3.2.3. Group Registration Management with MP-BGP 1472 The Group Registration (Section 3.1.3.1.3) information obtained via 1473 the registration messaging with a mobile host is shared among the 1474 group members using existing MP-BGP peering sessions. To achieve 1475 this, the MSF should allow for a configuration capability to identify 1476 the group membership by assigning a Group ID to the MP-BGP peers that 1477 belong to the same group. The same capability should be provided 1478 within the Mobility Route Reflectors in order to be able to 1479 successfully update the group members with the mobile node 1480 registration information. 1482 The mobile host registration information includes the IP address of 1483 the mobile host, the Group ID, the priority and the ASTI codes as 1484 well as the MAC address of the mobile host. This information is 1485 encoded in the Address Family structure using the AFI values 1486 specified in Section 3.2.1 but with a specifically designated value 1487 of SAFI. The encoded information is then carried in the 1488 MP_REACH_NLRI or MP_UNREACH_NLRI. 1490 Specifically the following new SAFI value is defined: 1492 Mobility IPv4 Unicast - AFI X1 SAFI Y2 1494 Mobility IPv6 Unicast - AFI X2 SAFI Y2 1496 The NLRI encoding is shown below: 1498 0 1 2 3 1499 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1500 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1501 | MP-BGP NEXT_HOP | 1502 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1503 | Reserved |H| Rri.|ASTI |G| Group ID | 1504 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1505 | Mobile Host IP Address | 1506 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1507 | Group Virtual IP Address | 1508 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1509 | Mobile Host MAC Address (first 32 bits) | 1510 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1511 | Last 16 bits | Reserved | 1512 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1513 | Correlation ID | 1514 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1516 Group Registration NLRI Encoding 1518 Figure 19 1520 MP-BGP NEXT_HOP - Router ID of the MPLS LER originating the Group 1521 Registration Update. This address may be carried in the IPv4 or 1522 IPv6 format depending on the {AFI, SAFI} pair used. 1524 H - Mobile Node Type Indication. 0 = Mobile Host 1526 Pri. - A 3-bit priority code (0-7). 1528 ASTI - Application Service Type Indication. This 3-bit field may 1529 be used to indicate to the MSF what type of service is to be used 1530 by the mobile host. For example, "Internet Access Only" or Full 1531 Mobile-to-Mobile Routing". This indication can then be mapped to 1532 the Network Update Mode Code used in the Mobility Binding 1533 structure. 1535 G - Group Registration Requested (1) 1537 Group ID - Unique Registration Group Number. Should be zero if G 1538 = 0 1540 Mobile Host IP Address - IPv4 or IPv6 Address of the mobile host. 1541 This address may be carried in the IPv4 or IPv6 format depending 1542 on the {AFI, SAFI} pair used. 1544 Group Virtual IP Address - IPv4 or IPv6 address assigned for the 1545 group and joined by all LER interfaces participating in the MSF. 1546 For IPv6 this may be the Anycast IP address. 1548 Mobile Host MAC Address - MAC address of the mobile host. 1550 Correlation ID - a number used to keep track of the registration 1551 requests and the corresponding reply message pairs. 1553 The group registration information updates may be sent periodically 1554 by the group members. The registration information for multiple 1555 mobile hosts may be aggregated in a single MP-BGP UPDATE message. 1556 The mobile host registration information may be explicitly withdrawn 1557 by the group member that was the last to "hear" from the mobile host. 1559 If a group member receives the MP-BGP registration information update 1560 listing a mobile host that has an active local registration entry, 1561 the local registration information must be silently discarded and the 1562 corresponding local Mobility Binding deleted. The local Mobility 1563 Label should be returned to the local available label pool. 1565 If a local registration entry for a mobile host has expired, and if a 1566 mobile host registration information is not found in the incoming 1567 periodic MP-BGP registration information updates from any of the 1568 group members, the group member should send the MP-BGP registration 1569 information update carrying the host's registration information in 1570 the MP_UNREACH_NLRI attribute. In addition the group member should 1571 initiate a network update using the MP_UNREACH_NLRI with the encoded 1572 Mobility Binding for the host in order to withdraw the Mobility 1573 Binding from the MSF databases of the MPLS LER nodes. 1575 3.2.4. BGP Capability Advertisement 1577 The {AFI, SAFI} pairs defined in this document for mobility 1578 management must be supported by all BGP speakers participating in 1579 mobility management. A BGP Capability Advertisement as specified in 1580 [RFC4760] must be used by the BGP speakers to ensure compatibility. 1582 3.3. Mobile Application Priority Indication and Recognition 1584 Given the sensitivity of applications to the network service 1585 disruption the MSF function should include a mechanism by which an 1586 application may indicate the level of tolerance to the disruption due 1587 to the network handling of the hand-off process. This indication may 1588 be encoded in the registration messaging payload and then 1589 incorporated into the Mobility Binding protocol structure. The 1590 application sensitivity prioritization scheme may be used to control 1591 the Mobility Binding processing priority during the distribution 1592 process. For example a mobile host running a real time interactive 1593 application may be given a higher processing priority over the mobile 1594 host running an elastic data transfer application. The 1595 prioritization of processing leads to a differential treatment of the 1596 mobile application at various processing points of the mobile network 1597 such as the ingress MSF, the intermediate hierarchical route 1598 processing by MP-BGP Route Reflectors and the egress MSF. 1600 In addition to the processing priority, the priority indication 1601 mechanism may be used to implement the network update grouping and 1602 timing policies in a manner that could decrease the frequency of the 1603 updates and thus increase the scalability of the network. 1604 Specifically, the indicated application priorities may be mapped into 1605 the network update classes where the top priority may get an 1606 immediate network update and the lower priorities may be organized 1607 into classes. For each class the network update process may be 1608 delayed for a time period that is not expected to result in the 1609 unreasonable disruption to an application of a given priority level. 1610 The network updates for any new registration events of the same 1611 priority level that have occurred during the corresponding delay 1612 period may be grouped in a single MP-BGP update message. If a single 1613 update message cannot carry all of the newly arrived registrations an 1614 additional update should be created and sent. The update mode may be 1615 determined from the Application Service Type Indication communicated 1616 during the registration. 1618 3.4. Application Service Type Indication 1620 Application Service Type Indication (ASTI) is a 3-bit field that may 1621 be used to indicate to the MSF what type of service is to be used by 1622 the mobile host. For example, "Internet Access Only" or "Full 1623 Mobile-to-Mobile Routing". This indication may then be mapped to the 1624 Network Update Type Code used in the Mobility Binding structure. For 1625 example, if ASTI code 001 (binary) is used to indicate the "Internet 1626 Access Only" service, the local MSF may use the Selective Downstream 1627 Push (see Section 4.1.2) Network Update mode. In addition the MSF 1628 may include the corresponding Update Type code in the Mobility 1629 Binding structure in order to indicate to the Mobility Route 1630 Reflectors that the Selective Downstream Push is to be used. 1632 4. Network Update and Hand-off Processing 1634 4.1. Network Update Modes and Types 1636 The following four modes for the Mobility Binding Distribution or 1637 Withdrawal are proposed: i) unsolicited downstream push, ii) 1638 selective downstream push, iii) predictive downstream push, and iv) 1639 hierarchical on-demand distribution. 1641 4.1.1. Unsolicited Downstream Push Mode 1643 In this mode the originating LER node updates all other MSF enabled 1644 LER nodes that are directly peered with it. In case of a 1645 hierarchical topology the originating LER node sends a MP-BGP update 1646 with the Mobility Binding information to a Route Reflector which in 1647 turn updates all of the participating MSF enabled LER Route Reflector 1648 clients. Thus the network wide update can only considered to be 1649 complete if and only if all of the MSF LER nodes are updated. 1650 Clearly this distribution mode has scalability limitations and may be 1651 applicable for a relatively small number of the MSF enabled LER 1652 nodes. The Update Mode Code for this mode is binary 000. 1654 4.1.2. Selective Downstream Push Mode 1656 In this mode the Mobility Binding updates are only sent to a select 1657 set of the MSF enabled LER nodes. The underlying idea for this mode 1658 is that it is very likely that the most used destinations from the 1659 mobile host when it communicates with the Internet are the 1660 destinations reachable via a finite set of the service provider's 1661 Internet gateway nodes which are in turn reachable via a finite set 1662 of the MSF enabled LER nodes. As such, when a mobile host registers 1663 with the serving MSF, instead of using the Unsolicited Downstream 1664 Push to all LER nodes, the Mobility Binding update for this mobile 1665 host would be sent to a finite set of the LER nodes connected to the 1666 service provider Internet gateways. This mode can be used for the 1667 initial update process and the Unsolicited Downstream Push can be 1668 used at a later point in time. The Update Type Mode for this mode is 1669 binary 001. 1671 4.1.3. Predictive Downstream Push Mode 1673 In this mode the Mobility Binding updates are sent to those MSF 1674 enabled LER nodes which are identified as a NEXT_HOP for the FEC (and 1675 the corresponding LSP) leading to the destination of the packet 1676 originated by a mobile node. This mode is based on the fact that if 1677 the destination FEC exists in the serving MSF LER's routing table, 1678 and the mobile node sends a packet to the FEC, the LER will perform 1679 the label imposition (for the infrastructure label) by selecting the 1680 label corresponding to the FEC NEXT_HOP. This NEXT_HOP in turn 1681 identifies the destination MSF enabled LER node to which the Mobility 1682 Binding update needs to be sent. The predictive feature of this mode 1683 comes from the fact that the Mobility Binding update destination is 1684 predicted as the result of the originating LER's lookup of the 1685 destination FEC and its NEXT_HOP. Clearly it is likely that the LER 1686 node to which the predictive Mobility Binding update is sent may 1687 receive the reply packet from the mobile node's destination before 1688 the Mobility Binding for the originating host is received. In this 1689 case the LER that is being updated may buffer the reply packet for a 1690 reasonable period of time to wait for the mobility update. The 1691 Update Mode Code for this mode is binary 010. 1693 4.1.4. Hierarchical On-Demand Distribution Mode 1695 The Mobility Binding update is first sent by a serving MSF LER to a 1696 set of Mobility Route Reflectors using the Selective Downstream Push. 1697 Once the Mobility Route Reflectors have been updated, all other LER 1698 nodes must explicitly request Mobility Labels from the Mobility Route 1699 Reflectors for packets destined to a mobile node. The Update Mode 1700 Code for this mode is binary 011. 1702 4.1.4.1. On-Demand Requests for Mobility Binding Information 1704 To support the Hierarchical On-Demand Distribution Network Update 1705 Mode the following explicit Mobility Binding information request 1706 procedure based on MP-BGP may be used. When a MPLS LER supporting 1707 MPLS Mobility receives an IP packet, it first should check if the 1708 Destination Address listed in the IP header belongs to the overall IP 1709 address range assigned to the mobility functions and the 1710 corresponding mobile device fleet. If the Destination Address falls 1711 within this range and the matching Mobility Binding is present in the 1712 LER MSF database, the packet should be encapsulated using the 1713 appropriate MPLS label stack and forwarded on the LSP toward the LER 1714 that is listed as the "Origin MP-BGP NEXT_HOP" in the Mobility 1715 Binding. If the IP address is outside of the mobility fleet range 1716 the packet must be treated in accordance with the conventional rules 1717 based on either the IP or MPLS forwarding tables. 1719 If the packet falls into the mobility fleet range and no matching 1720 Mobility Binding entry exists in the MSF database, the LER should 1721 send an on-demand request for Mobility Binding Information to the 1722 designated Mobility Route Reflector. This request is encoded as a 1723 special type of the MP_REACH_NLRI attribute using a specific SAFI 1724 value and one of the AFI values defined earlier. The Mobility Route 1725 Reflector should process the request and return the Mobility Binding 1726 update to the requesting LER using the NLRI encoding shown in 1727 Section 3.2.2. 1729 Specifically the following new SAFI value is defined for the On- 1730 Demand Mobility Binding Information Request: 1732 Mobility IPv4 Unicast - AFI X1 SAFI Y3 1734 Mobility IPv6 Unicast - AFI X2 SAFI Y3 1736 The NLRI encoding is shown below: 1738 0 1 2 3 1739 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1740 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1741 | MP-BGP NEXT_HOP | 1742 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1743 |Request Type | Area_ID | Number of Addresses | 1744 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1745 | IP Destination Address | 1746 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1747 | IP Destination Address 1748 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+... 1750 NLRI Encoding for On-Demand Mobility Binding Request 1752 Figure 20 1754 MP-BGP NEXT_HOP - Router ID of the MPLS LER originating the On- 1755 Demand Mobility Binding Information Request. This address may be 1756 carried in the IPv4 or IPv6 format depending on the {AFI, SAFI} 1757 pair used. 1759 Request Type - To be defined (may be "Specific, Partial, ALL or 1760 LRL"). 1762 Area_ID - An Identifier (1-255) associated with the Area Mobility 1763 Route Reflector. Area_ID=0 must be used for initial registrations 1764 by mobile nodes. 1766 Number of Addresses - Number of IP Destination Addresses listed in 1767 the On-Demand Request for which the Mobility Binding Information 1768 is requested 1770 IP Destination Address - The IPv4 or IPv6 address of a mobile host 1771 for which the Mobility Binding Information is requested. 1773 If the Request Type is not equal to LRL - Last Requestor List, the 1774 Mobility Route Reflector (mRR) should reply with a regular Mobility 1775 Binding Update. If the request type is equal to LRL, then the 1776 following reply format should be used: 1778 0 1 2 3 1779 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1780 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1781 | MP-BGP NEXT_HOP | 1782 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1783 |Request Type | Reserved | Number of Addresses | 1784 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1785 | LRL Length | IP Destination + | 1786 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1787 | Address | Last Requestor + | 1788 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1789 | Router_ID | L.R. Area_ID | Last + | 1790 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1791 | Requestor Router_ID | L.R. Area_ID | LRL + | 1792 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1793 | Length | IP Destination + | 1794 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1795 | Address | Last Requestor + | 1796 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1797 | Router_ID | L.R. Area_ID | 1798 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+... 1800 NLRI Encoding for On-Demand LRL Reply 1802 Figure 21 1804 MP-BGP NEXT_HOP - Router ID of the MPLS LER originating the On- 1805 Demand LRL Reply. This address may be carried in the IPv4 or IPv6 1806 format depending on the {AFI, SAFI} pair used. 1808 Request Type - LRL Reply. 1810 Number of Addresses - LRL's in the reply 1812 IP Destination Address - The IPv4 or IPv6 address of a mobile host 1813 for which the LRL Information is requested. 1815 Last Requestor Router_ID - IP Address of the LER from which the 1816 On-Demand Mobility Binding Information Request for the mobile node 1817 in question was last received (may be more than one). 1819 L.R. Area_ID - ID of the Area mRR serving the LER from which the 1820 On-Demand Mobility Binding Information Request for the mobile node 1821 in question was last received (may be more than one). 1823 4.1.5. Network Update Types 1825 The network update types are carried within the Mobility Binding 1826 structure and are used in the hierarchical mobility management 1827 environment to indicate the nature of the update and the subsequent 1828 processing behavior by the appropriate network elements such as the 1829 Area Mobility Route Reflector (AMRR), Area Label Edge Router (ALER) 1830 and the Label Edge Router (LER). Please see section Section 4.1.6. 1832 4.1.5.1. Internal Update Type 1834 An internal update is initiated by an LER node local to a Mobility 1835 Area and carries the Mobility Binding information for a locally 1836 registered mobile device. The internal update is sent by an LER to 1837 the AMRR in order to update the ALER node. The internal update may 1838 also be sent by the ALER node to AMRR in response to the external 1839 update received by the ALER about the Mobility Bindings originating 1840 outside a local area. The Update Type Code for the Internal Update 1841 is binary 0000. 1843 4.1.5.2. External Update Type 1845 An external update is originated by the ALER in response to an 1846 internal update and is sent to the AMRR. The Update Type Code for 1847 the External Update is binary 0001. 1849 4.1.6. Network Hierarchy Considerations 1851 The first three update modes are directly applicable for the flat MSF 1852 LER peering topology and the fourth to the hierarchical peering 1853 environment. In the hierarchical peering environment only 1854 Unsolicited Downstream Push does not require any modifications to the 1855 Route Reflector operation. The Selective and Predictive modes 1856 require that the Route Reflectors perform selective MP-BGP updates 1857 for the Mobility Bindings distribution. This can be achieved by a 1858 modification of the Route Reflector update process where destinations 1859 of the selective updates indicated by the Update Mode Code can be 1860 derived from the "Target NEXT_HOP" parameter in the Mobility Binding 1861 structure. The Hierarchical On-Demand mode requires the Route 1862 Reflectors to store the Mobility Bindings and respond to the on- 1863 demand Mobility Binding requests initiated by the client MSF LER 1864 nodes or other Mobility Route Reflectors. 1866 4.1.7. Regionalization and Scalability 1868 To improve the scalability of the network update process the entire 1869 serving network may be divided into the Mobility Areas. Each 1870 Mobility Area is served by an Area Mobility Route Reflector (AMRR) 1871 and optionally with an Area LER, with the individual MSF LER nodes 1872 falling within the area and acting as the Route Reflector Clients. 1873 Each MSF LER node in turn may serve a specific geographic region 1874 called a Mobility Region that is covered by a given set of Radio 1875 Access Networks using Direct or In-direct Attachment options. This 1876 type of the hierarchical regionalized mobility signaling 1877 infrastructure is referred to as the Hierarchical Mobility Label 1878 Based Network (H-MLBN) and is shown in the figure below. 1880 AMRR1/ALER1 AMRR3/ALER3 1881 +----+ +----+ 1882 | +------------------+ `. 1883 .++-+-+ AMRR2/ALER2 +--+-\ `. 1884 .'//| | +----+ | |`. \ 1885 .' /| | +--------+ +---------+ |\ \ `. 1886 Mobility Area 1 ++++-\ Mobility Area 3 1887 .' / / | /\ \ `. | \ \ `. 1888 .' / | | Mobility Area 2 | \ `. `. 1889 +-.' / +-/ | / | \ \ | | \ \ 1890 +-+ +-/ +-+ +-\ | \ \ \ \-+ \ `.-+`. 1891 LER11 +-+ LER13+-+ +-/ | \-+ `. +-+ \-+ +-+ +`. 1892 . LER12 . LER14 +-+ +-\ +-+ +-\ LER31 +-+ LER33+-+ 1893 / \ . / \ . LER21 +-+ LER23+-+ . LER32 . LER34 1894 ; : / \ ; : / \ . LER22 . LER24 / \ . / \ . 1895 |11 | ;12 :|13 |;14 : / \ . / \ . ; : / \ ; : / \ 1896 | | | || || | ;21 : / \ ; : / \ |31 |;32 :|33 |;34 : 1897 |++ | | || || | | | ;22 :|23 |;24 : | || || || | 1898 :++MN | |: ;| | | | | || || | | || || || | 1899 \ / : ; \ / : ; | | | || || | : ;| |: ;|++ | 1900 ' \ / ' \ / : ; | |: ;| | \ / : ; \ / :++CN 1901 ' ' \ / : ; \ / : ; ' \ / ' \ / 1902 ' \ / ' \ / ' ' 1903 ' ' 1904 Mobility Regions 1906 Hierarchical Mobility Label Based Network (H-MLBN) 1908 Figure 22 1910 4.1.7.1. Hierarchical Mobility Label Based Network (H-MLBN) 1912 The operation of H-MLBN is based on the Hierarchical On-Demand 1913 Network Update mode and requires the individual MSF LER nodes to only 1914 directly update their respective Area Mobility Route Reflectors 1915 (using the Selective Update Mode and the Internal Update Type). 1916 After the Area mRR's have been updated with the Mobility Binding 1917 information, these bindings may be explicitly requested by the MSF 1918 LER's in the same Mobility Area or the LER's in other areas via their 1919 Area mRR's. To facilitate the hand-off process a Last Requestor List 1920 (LRL) is introduced and associated with each Mobility Binding at the 1921 Area mRR level. The LRL is a list of 2-tuples where each 2-tuple 1922 consists of the Router_ID and Area_ID of the AMRR nodes that have 1923 requested Mobility Binding information for a particular mobile node. 1924 The logical operation of H-MLBN is described below based on 1925 Figure 22. 1927 1. Assume that a previously unknown MN initiated a Discovery and 1928 Registration process in the Mobility Region 11. Upon successful 1929 registration MN communicates its IP address to the MSF in LER11 and 1930 receives the related MSF information including the Area_ID=1. 1931 (During the registration the newly initialized MN should use 1932 Area_ID=0). 1934 2. LER11 creates a Mobility Binding for the MN and updates AMRR1 1935 using the Selective Mode and Internal Type, and specifying the MN's 1936 IP address, It's own Router_ID, the locally significant Mobility 1937 Label and the Area_ID=1. AMRR1 stores the received Mobility Binding 1938 and associates an empty LRL with it. 1940 3. Assume that a Correspondent Node (CN) in the Mobility Region 34 1941 sends a packet to the MN in the Mobility Region 11. The packet 1942 reaches LER34. 1944 4. LER34 identifies that the packet falls into the mobility address 1945 range and requests Mobility Binding information from its Area MRR3 1946 using On-Demand Mobility Binding Request (see Figure 20). LER34 uses 1947 the value of the Area_ID=3 in the request. 1949 5. Since AMRR3 does not have the Mobility Binding for the MN it 1950 forwards the requests to both AMRR1 and AMRR2. AMRR1 replies with 1951 the Mobility Binding and AMRR3 forwards the reply to LER34. AMRR1 1952 associates an LRL with the Mobility Binding listing the AMRR3's 1953 Router_ID and the Area_ID=3. 1955 6. LER34 forwards the packet to the MN using the LSP between LER11 1956 and LER34 and a stacked Mobility Label extracted from the received 1957 Mobility Binding. If the H-MLBN makes use of the Area LER nodes 1958 (thus also using the forwarding plane hierarchy) the Mobility Labels 1959 may include the ALER's Router_ID instead of the LER Router_ID. Thus 1960 the path between the LER nodes may consist of multiple segments (a 1961 segmented LSP): LER-ALER, ALER-ALER, ALER-LER. 1963 7. Assume that MN now moves into the Mobility Region 22. It 1964 initiates a new Discovery and Registration procedure and registers 1965 with the MSF at LER22 specifying its IP address and the Last 1966 Area_ID=1. 1968 8. LER22 creates a local Mobility Binding for the MN and updates its 1969 regional AMRR2 using Selective Mode and Internal Type, and sending 1970 the Area_ID=1 along with the Mobility Binding. 1972 9. AMRR2 receives the new Mobility Binding and examines the 1973 associated value of Area_ID. If it is not equal to its own, then the 1974 LRL for this binding must be requested from the AMRR identified by 1975 the Area_ID. In this case AMRR2 sends the On-Demand request to AMRR1 1976 asking for the associated LRL created in step 5. 1978 10. AMRR2 receives the LRL={Router_ID=LER34, Region_ID=3} from AMRR1 1979 (see Figure 21) and sends a Mobility Binding update to AMRR3 using 1980 the Selective Downstream Push Mode and the External Update Type and 1981 with the "Target MP-BGP NEXT_HOP" set to the LER34 Router_ID. 1983 11. AMRR3 receives the updated Mobility Binding and looks up the 1984 "Target MP-BGP NEXT_HOP". In this case it is equal to the LER34 1985 Router_ID. AMRR3 updates LER34 with the new Mobility Binding using 1986 Selective Mode and Internal Type. LER34 starts to forward packets to 1987 the MN using the LSP between LER34 and LER22 (listed as the "Origin 1988 MP-BGP NEXT_HOP" in the updated Mobility Binding) and the new overlay 1989 Mobility Label. 1991 4.2. Hand-off Processing 1993 The use of the Multi-Protocol BGP for mobility management allows a 1994 simple basic hand-off processing scheme to be implemented. In 1995 particular, when a mobile node detects that it can no longer receive 1996 the keepalive acknowledgements from the serving MSF it initiates the 1997 new discovery and registration procedure. After the successful 1998 registration the new serving MSF will assign and distribute a new 1999 Mobility Binding to the rest of the participating LER nodes thus 2000 replacing the corresponding old Mobility Binding entries in their MSF 2001 databases. Once the entries have been replaced by the new Mobility 2002 Binding the LER nodes will automatically forward the packets destined 2003 for the mobile node onto the new LSPs connecting to the mobile node's 2004 new serving MSF and the corresponding new Radio Access Network. 2006 The described hand-off procedure provides a basic hand-off handling 2007 in that it requires a new mobile node registration to trigger the 2008 Mobility Binding update to the network. The service disruption due 2009 to the time required to detect the loss of communication and to 2010 discover the new MSF and register with it can be minimized by 2011 selecting the fast keepalive timers but this in turn will result in 2012 the increased processing overhead and a possible impact on 2013 scalability. At the same time the frequency of the hand-offs between 2014 the MSF LER nodes can reasonably be expected to be much lower then 2015 the frequency of the Layer 2 hand-offs because the MSF enabled LER is 2016 expected to serve a large area potentially covered by multiple Radio 2017 Access Networks. Therefore a reasonable configuration of the 2018 keepalive timers and the low frequency of the MSF-to-MSF hand-offs 2019 may result in an acceptable network responsiveness especially for 2020 disruption tolerant applications. 2022 In cases where the application sensitivity requires a better network 2023 responsiveness a number of more sophisticated hand-off methods can be 2024 implemented. One of the methods may make use of the Group 2025 Registration as described above. In this case no discovery or 2026 registration is required from the mobile node when it moves into the 2027 new service area - it simply must continue to send packets to the 2028 group address and whichever group member happens to be serving the 2029 mobile node will distribute the pre-assigned Mobility Label to update 2030 the network. Thus the hand-off latency becomes only a function of 2031 the MP-BGP update processing as opposed to being a function of a 2032 combination of a potentially lengthy discovery and registration as 2033 well as the MP-BGP update procedures. Again, this scheme requires a 2034 trade-off analysis between the gain in the network responsiveness and 2035 the cost in signaling and processing required to maintain the shared 2036 registration table. 2038 4.3. Micro-Mobility Handling 2040 In the context of Mobile IP Micro-Mobility can be defined as a range 2041 of the mobile node movements that do not require re-registrations 2042 with the Mobile IP HA. A number of proposals exist that are targeted 2043 to extend the range of micro-mobility by utilizing the hierarchical 2044 mobility management schemes. 2046 In the context of this document micro-mobility is defined as the 2047 range of the mobile node's movements that do not result in the 2048 registration with a new MSF or the network update by MP-BGP, or both. 2049 As such the following two micro-mobility scenarios are considered by 2050 this proposal. 2052 4.3.1. Local Micro-Mobility 2054 Local micro-mobility is defined as the range of movements of the 2055 mobile node that is contained within the serving area of a given MSF 2056 enabled LER node. Referring to Figure 1 this moving pattern would 2057 correspond to the mobile node transitioning between the radio cells 2058 associated with the L3 logical interfaces local to the serving LER 2059 node. Clearly such a movement pattern should not result in either 2060 the re-registration with the MSF or the network update by MP-BGP. 2062 In order to support Local Micro-Mobility the MSF should have the 2063 capability of "tracking" the mobile node association with the LER L3 2064 logical interfaces. This "tracking" may simply be based on the 2065 reception of the datagrams from the mobile node. If the packets from 2066 the same L2 address and L3 source addresses started arriving on a new 2067 L3 logical interface of the LER and the MSF registration for the 2068 mobile node in question is active the MSF should associate the new L3 2069 logical interface with the existing registration entry and the 2070 corresponding local Mobility Binding. 2072 4.3.2. Group Micro-Mobility 2074 Group Micro-Mobility makes direct use of the Group Registration 2075 described in Section 3.1.3. In this case the Group Micro-Mobility is 2076 defined as the range of the mobile node's movements that do not 2077 result in the MSF re-registration process. Group Micro-Mobility 2078 still requires the network update by MP-BGP. 2080 5. Datagram Delivery 2082 The delivery of packets from the MSF registered mobile node to other 2083 network destinations uses the same processing as in the other MPLS 2084 services. Namely, when a packet is received from the mobile node the 2085 LER looks up the MPLS forwarding database to find a FEC to which the 2086 destination IP address belongs. Once the FEC is identified the 2087 corresponding MPLS label (or label stack) is used to send the packet 2088 on the LSP toward the destination. 2090 For the packets destined to the mobile node, when the packet is 2091 received by the LER the MSF performs a lookup in the overlay MPLS 2092 forwarding table to find the Mobility Binding matching the 2093 destination address of the mobile node (this binding entry was 2094 populated as the result of the Mobility Binding Distribution 2095 process). Once the match is found the inner MPLS label is pushed 2096 onto the MPLS label stack. Then the LER performs an additional 2097 lookup to find a FEC and the corresponding label matching the "Origin 2098 MP-BGP NEXT_HOP" LER IP address associated with this Mobility 2099 Binding. This outer label is then pushed onto the MPLS label stack 2100 and the packet is forwarded on the LSP. 2102 At the receiving MSF enabled LER the packet is processed and the 2103 inner MPLS label is examined to find the reverse Mobility Binding 2104 match in order to identify the IP address of the mobile node. Once 2105 the IP address is identified the corresponding Layer 2 address is 2106 found in the MSF registration database. The packet payload is then 2107 encapsulated into the Layer 2 protocol and delivered to the mobile 2108 node. 2110 In the case when the mobility service is provided to the mobile 2111 router, the forwarding of packets follows the same procedure for the 2112 service provider MPLS network segment. The packet forwarding between 2113 the mobile router and the serving MSF enabled LER does not have to 2114 use MPLS and can be based on IPv4 or IPv6 and the corresponding radio 2115 attachment layer 2 protocol. 2117 6. Security Considerations 2119 The Lightweight Registration procedure (see Section 3.1.3.1.1) and 2120 the associated Network Update and traffic processing provides the 2121 capability to bypass the Full Registration mode in favor of the 2122 ability to significantly decrease the registration processing time. 2123 From the security perspective this procedure should only be allowed 2124 if the layer 2 radio access network provides acceptable mobile node 2125 authentication. 2127 To provide for stronger authentication, the Full or the Group 2128 Registration procedures must be used (see Section 3.1.3.1.2, 2129 Section 3.1.3.1.3). These procedures allow to use additional 2130 authentication procedures by making use of the Registration Request 2131 and Reply message extensions (see Figure 10, Figure 11). 2133 For the Mobile Routers, existing routing protocol security procedures 2134 such as the peer authentication may be used. 2136 7. IANA Considerations 2138 New ICMP code values for message types 9, 10, 133 and 134: 2140 Type=10 - IPv4 Router Solicitation, Code=1 - MLBN MSF Discovery 2141 Extension 2143 Type=9 - IPv4 Router Advertisement, Code=1 - MLBN MSF 2144 Advertisement Extension 2146 Type=133 - IPv6 Router Solicitation, Code=1 - MLBN MSF Discovery 2147 Extension 2149 Type=134 - IPv6 Router Advertisement, Code=1 - MLBN MSF 2150 Advertisement Extension 2152 New UDP port number: 2154 UDP Port RRR for the MLBN Full and Group Registration Protocol. 2156 New {AFI, SAFI} pairs for MP-BGP: 2158 AFI=X1, SAFI=Y1 - MLBN Mobility Binding IPv4 Unicast 2160 AFI=X1, SAFI=Y2 - MLBN Group Registration IPv4 Unicast 2162 AFI=X1, SAFI=Y3 - MLBN On-Demand Binding Information IPv4 Unicast 2164 AFI=X2, SAFI=Y1 - MLBN Mobility Binding IPv6 Unicast 2166 AFI=X2, SAFI=Y2 - MLBN Group Registration IPv6 Unicast 2168 AFI=X2, SAFI=Y3 - MLBN On-Demand Binding Information IPv6 Unicast 2170 8. Acknowledgements 2172 The authors would like to thank Dr. Stuart Elby of Verizon 2173 Communications for his insights and valuable suggestions related to 2174 this work. 2176 9. Patent Issues 2178 The IETF has been notified of intellectual property rights claimed in 2179 regard to some or all of the specification contained in this 2180 document. For more information consult the online list of claimed 2181 rights. 2183 The IETF takes no position regarding the validity or scope of any 2184 Intellectual Property Rights or other rights that might be claimed to 2185 pertain to the implementation or use of the technology described in 2186 this document or the extent to which any license under such rights 2187 might or might not be available; nor does it represent that it has 2188 made any independent effort to identify any such rights. Information 2189 on the procedures with respect to rights in RFC documents can be 2190 found in BCP 78 and BCP 79. 2192 The IETF invites any interested party to bring to its attention any 2193 copyrights, patents or patent applications, or other proprietary 2194 rights that may cover technology that may be required to implement 2195 this standard. Please address the information to the IETF at 2196 ietf-ipr@ietf.org. 2198 10. Changes from Previous Revisions 2200 00 -> 01 2202 - Replaced Region_ID with Area_ID in MSF Registration and Mobility 2203 Bindings 2205 - Replaced UT field in Mobility Binding with the UM field 2207 - Replaced the Resv. field in Mobility Binding with the UT field 2209 - Added Area_ID to the Mobility Binding Structure 2211 - Added sections 4.1.5, 4.1.5.1 and 4.1.5.2 2213 - Modified Section 4.1.7. Used H-MLBN instead of MILS 2215 - Added informative reference [MLBN] 2217 - Added Section 10 2219 11. References 2221 11.1. Normative References 2223 [RFC1256] Deering, S., "ICMP Router Discovery Messages", RFC 1256, 2224 September 1991. 2226 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 2227 Requirement Levels", BCP 14, RFC 2119, March 1997. 2229 [RFC3107] Rekhter, Y. and E. Rosen, "Carrying Label Information in 2230 BGP-4", RFC 3107, May 2001. 2232 [RFC3344] Perkins, C., "IP Mobility Support for IPv4", RFC 3344, 2233 August 2002. 2235 [RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support 2236 in IPv6", RFC 3775, June 2004. 2238 [RFC3963] Devarapalli, V., Wakikawa, R., Petrescu, A., and P. 2239 Thubert, "Network Mobility (NEMO) Basic Support Protocol", 2240 RFC 3963, January 2005. 2242 [RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway 2243 Protocol 4 (BGP-4)", RFC 4271, January 2006. 2245 [RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private 2246 Networks (VPNs)", RFC 4364, February 2006. 2248 [RFC4443] Conta, A. and S. Deering, "Internet Control Message 2249 Protocol (ICMPv6) for the Internet Protocol Version 6 2250 (IPv6) Specification", RFC 4443, December 1998. 2252 [RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter, 2253 "Multiprotocol Extensions for BGP-4", RFC 4760, 2254 January 2007. 2256 [RFC4861] Narten, T., Nordmark, E., and W. Simpson, "Neighbor 2257 Discovery for IP Version 6 (IPv6)", RFC 4861, 2258 September 2007. 2260 [RFC5036] Andersson, L., Doolan, P., Feldman, N., Fredette, A., and 2261 B. Thomas, "LDP Specification", RFC 5036, January 2001. 2263 11.2. Informative References 2265 [MLBN] Berzin, O., "Mobility Label Based Network: Mobility 2266 Support in Label Switched Networks with Multi-protocol 2267 BGP", Comput.-Netw. doi:10.1016/j.comnet.2008.03.001, 2268 2008. 2270 [MM-MPLS] Langar, L., Toshme, S., and N. Bouabdallah, "An Approach 2271 for Mobility Modeling - Towards an Efficient Mobility 2272 Management Support in Future Wireless Networks", IEEE/ 2273 IFIP NOMS, 2006. 2275 Authors' Addresses 2277 Oleg Berzin 2278 Verizon Communications 2279 1717 Arch Street 2280 Philadelphia, PA 19103 2281 US 2283 Phone: +1 215-466-2738 2284 Email: oleg.berzin@verizon.com 2286 Andrew G. Malis 2287 Verizon Communications 2288 40 Sylvan Road 2289 Waltham, MA 02451 2290 US 2292 Phone: +1 781-466-2362 2293 Email: andrew.g.malis@verizon.com 2295 Full Copyright Statement 2297 Copyright (C) The IETF Trust (2008). 2299 This document is subject to the rights, licenses and restrictions 2300 contained in BCP 78, and except as set forth therein, the authors 2301 retain all their rights. 2303 This document and the information contained herein are provided on an 2304 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 2305 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND 2306 THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS 2307 OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF 2308 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 2309 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 2311 Intellectual Property 2313 The IETF takes no position regarding the validity or scope of any 2314 Intellectual Property Rights or other rights that might be claimed to 2315 pertain to the implementation or use of the technology described in 2316 this document or the extent to which any license under such rights 2317 might or might not be available; nor does it represent that it has 2318 made any independent effort to identify any such rights. Information 2319 on the procedures with respect to rights in RFC documents can be 2320 found in BCP 78 and BCP 79. 2322 Copies of IPR disclosures made to the IETF Secretariat and any 2323 assurances of licenses to be made available, or the result of an 2324 attempt made to obtain a general license or permission for the use of 2325 such proprietary rights by implementers or users of this 2326 specification can be obtained from the IETF on-line IPR repository at 2327 http://www.ietf.org/ipr. 2329 The IETF invites any interested party to bring to its attention any 2330 copyrights, patents or patent applications, or other proprietary 2331 rights that may cover technology that may be required to implement 2332 this standard. Please address the information to the IETF at 2333 ietf-ipr@ietf.org. 2335 Acknowledgment 2337 Funding for the RFC Editor function is provided by the IETF 2338 Administrative Support Activity (IASA).