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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 Internet Engineering Task Force P. Savola 2 Internet-Draft CSC/FUNET 3 Obsoletes: 2908 (if approved) September 16, 2004 4 Expires: March 17, 2005 6 Overview of the Internet Multicast Addressing Architecture 7 draft-savola-mboned-addrarch-00.txt 9 Status of this Memo 11 This document is an Internet-Draft and is subject to all provisions 12 of section 3 of RFC 3667. By submitting this Internet-Draft, each 13 author represents that any applicable patent or other IPR claims of 14 which he or she is aware have been or will be disclosed, and any of 15 which he or she become aware will be disclosed, in accordance with 16 RFC 3668. 18 Internet-Drafts are working documents of the Internet Engineering 19 Task Force (IETF), its areas, and its working groups. Note that 20 other groups may also distribute working documents as 21 Internet-Drafts. 23 Internet-Drafts are draft documents valid for a maximum of six months 24 and may be updated, replaced, or obsoleted by other documents at any 25 time. It is inappropriate to use Internet-Drafts as reference 26 material or to cite them other than as "work in progress." 28 The list of current Internet-Drafts can be accessed at 29 http://www.ietf.org/ietf/1id-abstracts.txt. 31 The list of Internet-Draft Shadow Directories can be accessed at 32 http://www.ietf.org/shadow.html. 34 This Internet-Draft will expire on March 17, 2005. 36 Copyright Notice 38 Copyright (C) The Internet Society (2004). 40 Abstract 42 The lack of up-to-date documentation on IP multicast address 43 allocation and assignment procedures has caused a great deal of 44 confusion. To clarify the situation, this memo describes the 45 allocation and assignment techniques and mechanisms currently (as of 46 this writing) in use. 48 Table of Contents 50 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 51 1.1 Terminology: Allocation or Assignment . . . . . . . . . . 3 52 2. Multicast Address Allocation . . . . . . . . . . . . . . . . . 4 53 2.1 Derived Allocation . . . . . . . . . . . . . . . . . . . . 4 54 2.1.1 GLOP Allocation . . . . . . . . . . . . . . . . . . . 4 55 2.1.2 Unicast-prefix -based Allocation . . . . . . . . . . . 4 56 2.2 Scope-relative Allocation . . . . . . . . . . . . . . . . 5 57 2.3 Static IANA Allocation . . . . . . . . . . . . . . . . . . 6 58 2.4 Dynamic Allocation . . . . . . . . . . . . . . . . . . . . 6 59 3. Multicast Address Assignment . . . . . . . . . . . . . . . . . 6 60 3.1 Derived Assignment . . . . . . . . . . . . . . . . . . . . 6 61 3.2 SSM Assignment inside the Node . . . . . . . . . . . . . . 7 62 3.3 Manually Configured Assignment . . . . . . . . . . . . . . 7 63 3.4 Static IANA Assignment . . . . . . . . . . . . . . . . . . 7 64 3.5 Dynamic Assignments . . . . . . . . . . . . . . . . . . . 8 65 3.6 Future Developments . . . . . . . . . . . . . . . . . . . 8 66 4. Multicast Address Discovery . . . . . . . . . . . . . . . . . 9 67 5. Summary and Future Directions . . . . . . . . . . . . . . . . 10 68 5.1 Prefix Allocation . . . . . . . . . . . . . . . . . . . . 10 69 5.2 Address Assignment . . . . . . . . . . . . . . . . . . . . 10 70 5.3 Future Actions . . . . . . . . . . . . . . . . . . . . . . 10 71 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11 72 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 73 8. Security Considerations . . . . . . . . . . . . . . . . . . . 11 74 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 75 9.1 Normative References . . . . . . . . . . . . . . . . . . . . 12 76 9.2 Informative References . . . . . . . . . . . . . . . . . . . 12 77 Author's Address . . . . . . . . . . . . . . . . . . . . . . . 14 78 A. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . . 14 79 Intellectual Property and Copyright Statements . . . . . . . . 15 81 1. Introduction 83 Good, up-to-date documentation of IP multicast is close to 84 non-existent. Particularly, this is an issue with multicast address 85 allocations (to networks and sites) and assignments (to hosts and 86 applications). This problem is stressed by the fact that there 87 exists confusing or misleading documentation on the subject 88 [RFC2908]. The consequence is that those who wish to learn of IP 89 multicast and how the addressing works do not get a clear view of the 90 current situation. 92 The aim of this document is to provide a brief overview of multicast 93 addressing and allocation techniques. 95 It is important to note that Source-specific Multicast (SSM) 96 [I-D.ietf-ssm-arch] does not have these addressing problems; hence, 97 this document focuses on Any Source Multicast (ASM) model. The 98 applicability of SSM has been briefly discussed in 99 [I-D.ietf-mboned-ipv6-multicast-issues]. 101 This memo obsoletes RFC 2908 and re-classifies it Historic. 103 1.1 Terminology: Allocation or Assignment 105 Almost all multicast documents and many other RFCs (such as DHCPv4 106 [RFC2131] and DHCPv6 [RFC3315]) have used the terms address 107 "allocation" and "assignment" interchangeably. However, the operator 108 and address management communities use these for two conceptually 109 different processes. 111 In unicast operations, address allocations refer to leasing a large 112 block of addresses from Internet Assigned Numbers Authority (IANA) to 113 a Regional Internet Registry (RIR), from RIR to a Local Internet 114 Registry (LIR) possibly through a National Internet Registry (NIR). 115 Address assignments, on the other hand, are the leases of smaller 116 address blocks or even single addresses to the end-user sites or 117 end-users themselves. 119 Therefore, in this memo, we will separate the two different 120 functions: "allocation" describes how larger blocks of addresses are 121 obtained by the network operators, and "assignment" describes how 122 applications, nodes or sets of nodes obtain a multicast address for 123 their use. 125 [[ NOTE IN DRAFT: is this choice of terminology too confusing? ]] 127 2. Multicast Address Allocation 129 Multicast address allocation, i.e., how a network operator might be 130 able to obtain a larger block of addresses, can be handled in a 131 number of ways as described below. 133 Note that these are all only pertinent to ASM -- SSM requires no 134 address block allocation because the group address has only local 135 significance (however, the address assignment inside the node is 136 still an issue discussed in Section 3.2). 138 2.1 Derived Allocation 140 Derived allocations take the unicast prefix or some other properties 141 of the network to determine unique multicast address allocations. 143 2.1.1 GLOP Allocation 145 GLOP address allocation [RFC3180] inserts the 16-bit public 146 Autonomous System (AS) number in the middle of the IPv4 multicast 147 prefix 233.0.0.0/8, so that each AS number can get a /24 worth of 148 multicast addresses. While this is sufficient for multicast testing 149 or small scale use, it might not be sufficient in all cases for 150 extensive multicast use. 152 A minor operational debugging issue with GLOP addresses is that the 153 connection between the AS and the prefix is not apparent from the 154 prefix, but has to be calculated (e.g., from [RFC3180], AS 5662 maps 155 to 233.22.30.0/24). A usage issue is that GLOP addresses are not 156 tied to any prefix but to routing domains, so they cannot be used or 157 calculated automatically. 159 2.1.2 Unicast-prefix -based Allocation 161 RFC 3306 [RFC3306] describes a mechanism which embeds up to 64 first 162 bits of an IPv6 unicast address in the prefix part of the IPv6 163 multicast address, leaving at least 32 bits of group-id space 164 available after the prefix mapping. 166 A similar mapping has been proposed for IPv4 167 [I-D.thaler-ipv4-uni-based-mcast], but it provides a rather low 168 amount of addresses (e.g., 1 per an IPv4 /24 block). While there 169 exist large networks without an AS number of their own, this has not 170 been seen to add sufficient value compared to GLOP addressing. 172 The IPv6 unicast-prefix -based allocations are an extremely useful 173 way to allow each network operator, even each subnet, obtain 174 multicast addresses easily, through an easy computation. Further, as 175 the IPv6 multicast header also includes the scope value [RFC3513], 176 multicast groups of smaller scope can also be used with the same 177 mapping. 179 The IPv6 Embedded RP technique [I-D.ietf-mboned-embeddedrp], used 180 with Protocol Independent Multicast - Sparse Mode (PIM-SM), further 181 leverages the unicast prefix based allocations, by embedding the 182 unicast prefix and interface identifier of the PIM-SM Rendezvous 183 Point (RP) in the prefix. This provides all the necessary 184 information needed to the routing systems to run the group in either 185 inter- or intra-domain operation. A difference to RFC 3306 is, 186 however, that the hosts cannot calculate their "multicast prefix" 187 automatically, as the prefix depends on the decisions of the operator 188 setting up the RP but rather needs to be communicated somehow. 190 All the IPv6 unicast-prefix -based allocation techniques provide 191 sufficient amount of multicast address space for the network 192 operators. 194 2.2 Scope-relative Allocation 196 Administratively scoped multicast [RFC2365] is provided by two 197 different means: under 239.0.0.0/8 in IPv4 or by 4-bit encoding in 198 the IPv6 multicast address prefix [RFC3513]. 200 As IPv6 scope-relative allocations can be handled with unicast-prefix 201 -based multicast addressing as described in Section 2.1.2, and there 202 is no need for separate scope-relative allocations, we'll just 203 discuss IPv4 in this section. 205 The IPv4 scope-relative prefix 239.0.0.0/8 is further divided to 206 Local Scope (239.255.0.0/16) and Organization Local Scope 207 (239.192.0.0/14); other parts of the administrative scopes are either 208 reserved for expansion or undefined [RFC2365]. 210 Topologies which act under a single administration can easily use the 211 scoped multicast addresses for their internal groups. Groups which 212 need to be shared between multiple routing domains (but not 213 propagated through Internet) are more problematic and typically need 214 an assignment of a global multicast address because their scope is 215 undefined. 217 There is a large number of multicast applications (such as "Norton 218 Ghost") which are restricted either to a link or a site, but it is 219 extremely undesirable to propagate them further (either to the rest 220 of the site, or beyond the site). Typically many such applications 221 have been given a static IANA address assignment; this makes it 222 challenging to implement proper propagation limiting -- which could 223 be easier if such applications could have been assigned specific 224 scope-relative addresses instead. This is an area of further future 225 work -- it might be able to mitigate this issue if there was more 226 coordination inside the scope-relative allocation block. 228 2.3 Static IANA Allocation 230 In some rare cases, some organizations may have been able to obtain 231 static multicast address allocations directly from IANA. Typically 232 these have been meant as a block of static assignments to multicast 233 applications, as described in Section 3.4. In principle, IANA does 234 not allocate multicast address blocks to the operators but GLOP or 235 Unicast-prefix -based allocations should be used instead. 237 2.4 Dynamic Allocation 239 RFC 2908 [RFC2908] proposed three different layers of multicast 240 address allocation and assignment, where layers 3 (inter-domain 241 allocation) and layer 2 (intra-domain allocation) could be applicable 242 here. Multicast Address-Set Claim Protocol (MASC) [RFC2909] is an 243 example of the former, and Multicast Address Allocation Protocol 244 (AAP) [I-D.ietf-malloc-aap] (abandoned in 2000 due lack of interest 245 and technical problems) is an example of the latter. 247 Both of the proposed allocation protocols were quite complex, and 248 have never been deployed or seriously implemented. 250 It can be concluded that there are no dynamic multicast address 251 allocation protocols, and other methods such as GLOP or 252 unicast-prefix -based addressing should be used instead. 254 3. Multicast Address Assignment 256 For multicast address assignment, i.e., how an application learns the 257 address it can use, or a node (or a set of nodes) learns an address 258 it could use for an application, has a number of options as described 259 below. 261 3.1 Derived Assignment 263 There are significantly fewer options for derived address assignment 264 compared to derived allocation. Derived multicast assignment is only 265 being specified for IPv6 link-scoped multicast 266 [I-D.ietf-ipv6-link-scoped-mcast], where the EUI64 is embedded in the 267 multicast address, providing a node with unique multicast addresses 268 for link-local ASM communications. 270 3.2 SSM Assignment inside the Node 272 While the SSM multicast addresses have only local (to the node) 273 significance, there is still a minor issue on how to assign the 274 addresses between the applications running on the same node (or more 275 precisely, an IP address). 277 This assignment is not considered to be a problem because typically 278 the addresses for the applications are selected manually or 279 statically, but if done using an API, the API could check that the 280 addresses do not conflict prior to assigning one. 282 3.3 Manually Configured Assignment 284 With manually configured assignment, the network operator which has a 285 multicast address prefix assigns the multicast group addresses to the 286 requesting nodes using a manual process. 288 Typically the user or administrator which wants to use a multicast 289 address for particular application requests an address from the 290 network operator using phone, email, or similar means, and the 291 network operator provides the user with a multicast address. Then 292 the user/administrator of the node or application manually configures 293 the application to use the assigned multicast address. 295 This is a relatively simple process in the beginning, but would 296 become unscalable if the multicast usage would get on a serious rise 297 (fortunately, we have dynamic assignment, see Section 3.5). Another, 298 separate issue is to ensure that the users wishing to use that 299 application are able to locate the configured multicast address 300 ("rendezvous" or "service discovery"); in this particular case, this 301 might call for e.g., DNS-based discovery of the multicast address. 303 This is the most commonly used technique when the multicast 304 application does not have a static IANA assignment. 306 3.4 Static IANA Assignment 308 In contrast to manually configured assignment, as described above, 309 static IANA assignment refers to getting a globally unique assignment 310 for the particular application directly from IANA. Guidelines for 311 IANA are described in [I-D.ietf-mboned-rfc3171bis]. 313 This is seen as lucrative because it's the simplest approach for 314 application developers because they can then hard-code the multicast 315 address, requiring no lease of the usable multicast address, and 316 likewise the client applications do not need to perform any kind of 317 service discovery (but depending on hard-coded addresses). However, 318 this is a bad approach architecturally, as we should focus on 319 enhancing and deploying service discovery and address assignment (as 320 needed) instead of encouraging a "land-grab" of multicast addresses. 322 In summary, there are applications which have obtained a static IANA 323 assignment, some of which are really needed, and some of which 324 probably should not have been granted. 326 3.5 Dynamic Assignments 328 The layer 1 of RFC 2908 [RFC2908] described dynamic assignment from 329 Multicast Address Allocation Servers (MAAS) to applications and 330 nodes, with Multicast Address Dynamic Client Allocation Protocol 331 (MADCAP) [RFC2730] and a proposal for DHCPv6 assignments 332 [I-D.jdurand-assign-addr-ipv6-multicast-dhcpv6] as examples. 334 Based on a multicast prefix, it would be rather straightforward to 335 deploy a dynamic assignment protocol which would lease group 336 addresses to the applications wishing to use multicast. For example, 337 only few have implemented MADCAP, and it's not significantly 338 deployed. Moreover, it is not clear how widely for example the APIs 339 for communication between the multicast application and the MADCAP 340 client operating at the host have been implemented [RFC2771]. 342 Based on that, a conclusion is that multicast is that either: 344 1. multicast is not significantly attractive in the first place, 346 2. manually configured assignments are sufficient for now, or 348 3. that there are other gaps why dynamic assignments are not seen as 349 a useful approach (for example, issues related to service 350 discovery/rendezvous). 352 In consequence, more work on rendezvous/service discovery will be 353 needed to make dynamic assignment more useful. 355 3.6 Future Developments 357 IPv6 could offer an alternative to dynamic assignments due to its 358 larger address space: if a multicast prefix (e.g., about 2^32 bits 359 worth of group-id's) is allocated to a subnet, it would be sufficient 360 to ensure that multiple applications running on that subnet do not 361 try to use the same address (selected e.g., using a random process). 362 This could call for a Duplicate Address Detection process, and/or a 363 way for the RPs to inform the hosts about the prefix that could be 364 used on each subnet (assuming Embedded-RP would be used). 366 4. Multicast Address Discovery 368 [[ NOTE IN DRAFT: it is not clear whether this section belongs in 369 this document at all; it is somewhat related, but could bear a more 370 extensive discussion elsewhere. It should likely go in a separate 371 document (if there was one discussing these problems!), or in an 372 appendix. Feedback is appreciated. ]] 374 As was noted in Section 3, multicast address discovery (i.e., service 375 discovery or "rendezvous") is a problem with multicast address 376 assignment. In particular, an acceptable mechanism (mechanisms such 377 as Service Location Protocol (SLP) [RFC2608] seem to have been 378 considered too complex) seems to be missing which the hosts wishing 379 to participate in a group could use to find the address of that group 380 [MBONED-IETF59]. 382 It is worth noting that as long as not deploying an address 383 assignment and service discovery protocols/mechanisms means that one 384 can get a static address assignment from IANA, there is little 385 interest from the application developers to actually do anything 386 except try to get the assignment from IANA. Conclusion: if we want 387 to use non-IANA processes, the assignments must be either forbidden 388 completely, or made sufficiently difficult that it's easier for the 389 application developers to take another route if a feasible mechanism 390 is available. 392 There are two issues in the service discovery: 394 1. The session initiator being able to publish the session somehow, 395 and 397 2. The session participants finding out about the session (rather 398 than creating their own). 400 When manually configured or static IANA assignments are used, 1) 401 should be relatively straightforward (if something needs to be 402 manually configured or statically assigned, putting it e.g., in DNS 403 should not be a problem). However, this is still more complex for 404 dynamic or derived assignments because it implies that the host or 405 the application has the right to make that publication on its own, 406 rather than through a manual process by an administrator. 408 2) is always a challenge, but could leverage for example DNS (e.g., 409 by relying on using SRV records with the DNS search path, as 410 described in [I-D.ymbk-dns-choices] and 411 [I-D.palet-v6ops-tun-auto-disc]). 413 5. Summary and Future Directions 415 This section summarizes the mechanisms and analysis discussed in this 416 memo, and presents some potential future directions. 418 5.1 Prefix Allocation 420 o Only ASM is affected by the assignment/allocation issues (however, 421 both ASM and SSM have roughly the same address discovery issues). 423 o GLOP allocations seem to provide a sufficient IPv4 multicast 424 allocation mechanism for now, but could be extended in future. 425 Scope-relative allocations provide the opportunity for internal 426 IPv4 allocations. 428 o Unicast-prefix -based addresses and the derivatives provide good 429 allocation strategy with IPv6, also for scoped multicast 430 addresses. 432 o Dynamic allocations are a too complex and unnecessary mechanism. 434 o Static IANA allocations are an architecturally unacceptable 435 approach. 437 5.2 Address Assignment 439 o Manually configured assignment is what's typically done today, and 440 works to a sufficient degree in smaller scale. 442 o Static IANA assignment has been done extensively in the past, but 443 it needs to be tightened down to prevent problems caused by 444 "land-grabbing". 446 o Dynamic assignment, e.g., using MADCAP have been implemented, but 447 there is no wide deployment, so a solution is there -- but either 448 there are other gaps in the multicast architecture or there is no 449 need for it in the first place, when manual configuration is 450 possible, and static IANA assignments are still there. 452 o Derived assignments are only applicable in a fringe case of 453 link-scoped multicast. 455 5.3 Future Actions 457 o Multicast address discovery/"rendezvous" needs to be analyzed at 458 more length, and an adequate solution provided; the result also 459 needs to be written down to be shown to the IANA static assignment 460 requestors. 462 o IPv6 multicast DAD and/or multicast prefix communication 463 mechanisms should be analyzed: whether there is demand or not, and 464 specify if so. 466 o The IETF should consider whether to specify more ranges of the 467 IPv4 scope-relative address space for static allocation for 468 applications which should not be routed over the Internet (such as 469 backup software, etc. -- so that these wouldn't need to use 470 global addresses which should never leak in any case). 472 o The IETF should seriously consider its static IANA allocations 473 policy, e.g., "locking it down" to a stricter policy (like "IETF 474 Consensus") and looking at developing the discovery/rendezvous 475 functions, if necessary. 477 6. Acknowledgements 479 Tutoring a couple multicast-related papers, the latest by Kaarle 480 Ritvanen [RITVANEN] convinced the author that the up-to-date 481 multicast address assignment/allocation documentation is necessary. 483 Multicast address allocations/assignments were discussed at the 484 MBONED WG session at IETF59 [MBONED-IETF59]. 486 Dave Thaler, James Lingard, and Beau Williamson provided useful 487 feedback for the preliminary version of this memo. 489 7. IANA Considerations 491 This memo includes no request to IANA, but as the allocation and 492 assignment of multicast addresses are related to IANA functions, it 493 wouldn't hurt if the IANA reviewed this entire memo. 495 IANA considerations in sections 4.1.1 and 4.1.2 of [RFC2908] still 496 apply to the administratively scoped prefixes. 498 (RFC-editor: please remove this section at publication.) 500 8. Security Considerations 502 This memo only describes different approaches to allocating and 503 assigning multicast addresses, and this has no security 504 considerations; the security analysis of the mentioned protocols is 505 out of scope of this memo. 507 Obviously, especially the dynamic assignment protocols are inherently 508 vulnerable to resource exhaustion attacks, as discussed e.g., in 509 [RFC2730]. 511 9. References 513 9.1 Normative References 515 [I-D.ietf-ipv6-link-scoped-mcast] 516 Park, J., "Link Scoped IPv6 Multicast Addresses", 517 draft-ietf-ipv6-link-scoped-mcast-05 (work in progress), 518 August 2004. 520 [I-D.ietf-mboned-embeddedrp] 521 Savola, P. and B. Haberman, "Embedding the Rendezvous 522 Point (RP) Address in an IPv6 Multicast Address", 523 draft-ietf-mboned-embeddedrp-07 (work in progress), July 524 2004. 526 [I-D.ietf-mboned-rfc3171bis] 527 Albanna, Z., Almeroth, K., Cotton, M. and D. Meyer, "IANA 528 Guidelines for IPv4 Multicast Address Assignments", 529 draft-ietf-mboned-rfc3171bis-02 (work in progress), March 530 2004. 532 [I-D.ietf-ssm-arch] 533 Holbrook, H. and B. Cain, "Source-Specific Multicast for 534 IP", draft-ietf-ssm-arch-06 (work in progress), September 535 2004. 537 [RFC2365] Meyer, D., "Administratively Scoped IP Multicast", BCP 23, 538 RFC 2365, July 1998. 540 [RFC3180] Meyer, D. and P. Lothberg, "GLOP Addressing in 233/8", BCP 541 53, RFC 3180, September 2001. 543 [RFC3306] Haberman, B. and D. Thaler, "Unicast-Prefix-based IPv6 544 Multicast Addresses", RFC 3306, August 2002. 546 [RFC3513] Hinden, R. and S. Deering, "Internet Protocol Version 6 547 (IPv6) Addressing Architecture", RFC 3513, April 2003. 549 9.2 Informative References 551 [I-D.ietf-malloc-aap] 552 Handley, M. and S. Hanna, "Multicast Address Allocation 553 Protocol (AAP)", June 2000. 555 [I-D.ietf-mboned-ipv6-multicast-issues] 556 Savola, P., "IPv6 Multicast Deployment Issues", 557 draft-ietf-mboned-ipv6-multicast-issues-01 (work in 558 progress), September 2004. 560 [I-D.jdurand-assign-addr-ipv6-multicast-dhcpv6] 561 Durand, J., "IPv6 multicast address assignment with 562 DHCPv6", 563 draft-jdurand-assign-addr-ipv6-multicast-dhcpv6-00 (work 564 in progress), June 2004. 566 [I-D.palet-v6ops-tun-auto-disc] 567 Palet, J. and M. Diaz, "Evaluation of v6ops Auto-discovery 568 for Tunneling Mechanisms", 569 draft-palet-v6ops-tun-auto-disc-01 (work in progress), 570 June 2004. 572 [I-D.thaler-ipv4-uni-based-mcast] 573 Thaler, D., "Unicast-Prefix-based IPv4 Multicast 574 Addresses", draft-thaler-ipv4-uni-based-mcast-00 (work in 575 progress), November 2001. 577 [I-D.ymbk-dns-choices] 578 Faltstrom, P., "Design Choices When Expanding DNS", 579 draft-ymbk-dns-choices-00 (work in progress), May 2004. 581 [MBONED-IETF59] 582 "MBONED WG session at IETF59", 583 . 585 [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC 586 2131, March 1997. 588 [RFC2608] Guttman, E., Perkins, C., Veizades, J. and M. Day, 589 "Service Location Protocol, Version 2", RFC 2608, June 590 1999. 592 [RFC2730] Hanna, S., Patel, B. and M. Shah, "Multicast Address 593 Dynamic Client Allocation Protocol (MADCAP)", RFC 2730, 594 December 1999. 596 [RFC2771] Finlayson, R., "An Abstract API for Multicast Address 597 Allocation", RFC 2771, February 2000. 599 [RFC2908] Thaler, D., Handley, M. and D. Estrin, "The Internet 600 Multicast Address Allocation Architecture", RFC 2908, 601 September 2000. 603 [RFC2909] Radoslavov, P., Estrin, D., Govindan, R., Handley, M., 604 Kumar, S. and D. Thaler, "The Multicast Address-Set Claim 605 (MASC) Protocol", RFC 2909, September 2000. 607 [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C. and 608 M. Carney, "Dynamic Host Configuration Protocol for IPv6 609 (DHCPv6)", RFC 3315, July 2003. 611 [RITVANEN] 612 Ritvanen, K., "Multicast Routing and Addressing", HUT 613 Report, Seminar on Internetworking, May 2004, 614 615 . 617 Author's Address 619 Pekka Savola 620 CSC - Scientific Computing Ltd. 621 Espoo 622 Finland 624 EMail: psavola@funet.fi 626 Appendix A. Open Issues 628 (This section will be removed or merged with the rest before 629 publication..) 631 o Is it worth the effort to (try to) [re]define the "allocation" and 632 "assignment" terms? There are a number of RFCs which use these 633 interchangeably, but other documents and operators/address 634 management community are more pedantic on that, and the feeling in 635 the IETF community seems to have been more strict on the 636 separation as well. 638 o Is the case for IPv4 Unicast-Prefix Base Multicast addressing 639 sufficiently strong, or could those organizations just get an AS 640 number themselves if they really wanted to do multicast? 642 o There is some pressure to expand the scope to cover routing as 643 well. That would enable us to discuss certain difficult issues 644 (e.g., how to deal with applications like "Norton Ghost"), but 645 could open a significant number of cans of worms as well. 647 Intellectual Property Statement 649 The IETF takes no position regarding the validity or scope of any 650 Intellectual Property Rights or other rights that might be claimed to 651 pertain to the implementation or use of the technology described in 652 this document or the extent to which any license under such rights 653 might or might not be available; nor does it represent that it has 654 made any independent effort to identify any such rights. 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