idnits 2.17.1 draft-ietf-mpls-multicast-encaps-04.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- ** It looks like you're using RFC 3978 boilerplate. You should update this to the boilerplate described in the IETF Trust License Policy document (see https://trustee.ietf.org/license-info), which is required now. -- Found old boilerplate from RFC 3978, Section 5.1 on line 21. -- Found old boilerplate from RFC 3978, Section 5.5, updated by RFC 4748 on line 385. -- Found old boilerplate from RFC 3979, Section 5, paragraph 1 on line 396. -- Found old boilerplate from RFC 3979, Section 5, paragraph 2 on line 403. -- Found old boilerplate from RFC 3979, Section 5, paragraph 3 on line 409. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- == No 'Intended status' indicated for this document; assuming Proposed Standard Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- -- The abstract seems to indicate that this document updates RFC3032, but the header doesn't have an 'Updates:' line to match this. -- The abstract seems to indicate that this document updates RFC4023, but the header doesn't have an 'Updates:' line to match this. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust Copyright Line does not match the current year -- The document seems to lack a disclaimer for pre-RFC5378 work, but may have content which was first submitted before 10 November 2008. If you have contacted all the original authors and they are all willing to grant the BCP78 rights to the IETF Trust, then this is fine, and you can ignore this comment. If not, you may need to add the pre-RFC5378 disclaimer. (See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (April 2007) is 6221 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-07) exists of draft-ietf-mpls-upstream-label-02 Summary: 1 error (**), 0 flaws (~~), 3 warnings (==), 9 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group Toerless Eckert 3 Internet Draft Eric C. Rosen (editor) 4 Expiration Date: October 2007 Cisco Systems, Inc. 5 Updates RFCs 3032 and 4023 6 Rahul Aggarwal 7 Yakov Rekhter 8 Juniper Networks, Inc. 10 April 2007 12 MPLS Multicast Encapsulations 14 draft-ietf-mpls-multicast-encaps-04.txt 16 Status of this Memo 18 By submitting this Internet-Draft, each author represents that any 19 applicable patent or other IPR claims of which he or she is aware 20 have been or will be disclosed, and any of which he or she becomes 21 aware will be disclosed, in accordance with Section 6 of BCP 79. 23 Internet-Drafts are working documents of the Internet Engineering 24 Task Force (IETF), its areas, and its working groups. Note that other 25 groups may also distribute working documents as Internet-Drafts. 27 Internet-Drafts are draft documents valid for a maximum of six months 28 and may be updated, replaced, or obsoleted by other documents at any 29 time. It is inappropriate to use Internet-Drafts as reference 30 material or to cite them other than as "work in progress." 32 The list of current Internet-Drafts can be accessed at 33 http://www.ietf.org/ietf/1id-abstracts.txt. 35 The list of Internet-Draft Shadow Directories can be accessed at 36 http://www.ietf.org/shadow.html. 38 Abstract 40 RFC 3032 established two data link layer codepoints for MPLS: one to 41 indicate that the data link layer frame is carrying an MPLS unicast 42 packet, and the other to indicate that the data link layer frame is 43 carrying an MPLS multicast packet. This specification updates RFC 44 3032 by redefining the meaning of these two codepoints. The former 45 "multicast codepoint" is now to be used only on multiaccess media, 46 and it is to mean "the top label of the following label stack is an 47 upstream-assigned label". The former "unicast codepoint" is to be 48 used in all other cases. Whether the data link layer payload is a 49 unicast MPLS packet or a multicast MPLS packet is now to be 50 determined by looking up the top label, rather than by the codepoint. 52 RFC 3032 does not specify the destination address to be placed in the 53 "MAC DA" field of an ethernet frame which carries an MPLS multicast 54 packet. This document provides that specification. 56 This document updates RFC 3032 and RFC 4023. 58 Contents 60 1 Specification of Requirements ........................ 2 61 2 Introduction ......................................... 3 62 3 Upstream-Assigned vs. Downstream-Assigned ............ 4 63 4 Ethernet Codepoints .................................. 6 64 5 PPP Protocol Field ................................... 6 65 6 GRE Protocol Type .................................... 6 66 7 IP Protocol Number ................................... 7 67 8 Ethernet MAC DA for Multicast MPLS ................... 7 68 9 IANA Considerations .................................. 8 69 10 Security Considerations .............................. 8 70 11 Normative References ................................. 8 71 12 Informative References ............................... 8 72 13 Authors' Addresses ................................... 9 73 14 Full Copyright Statement ............................. 9 74 15 Intellectual Property ................................ 10 76 1. Specification of Requirements 78 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 79 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 80 document are to be interpreted as described in [RFC2119]. 82 2. Introduction 84 RFC 3031 [RFC3031] defines the "Next Hop Label Forwarding Entry" 85 (NHLFE). The NHLFE for a particular label maps the label into a next 86 hop (among other things). When an MPLS packet is received, its top 87 label is mapped to an NHLFE, and the packet is sent to the next hop 88 specified by the NHLFE. 90 We define a particular MPLS label to be a "multicast label" in a 91 particular context if the NHLFE to which it is mapped in that context 92 specifies a set of next hops, with the semantics that the packet is 93 to be replicated, and a copy of the packet sent to each of the 94 specified next hops. Note that this definition accommodates the case 95 where the set of next hops contains a single member. What makes a 96 label a multicast label in a particular context is the semantics 97 attached to the set, i.e., the intention to replicate the packet and 98 transmit to all members of the set if the set has more than one 99 member. 101 RFC 3032 [RFC3032] established two data link layer codepoints for 102 MPLS: one to indicate that the data link layer frame is carrying an 103 MPLS unicast packet, and the other to indicate that the data link 104 layer frame is carrying an MPLS multicast packet. The term 105 "multicast packet" is not precisely defined in RFC 3032, though one 106 may presume that the "multicast" codepoint is intended to identify 107 the packet's top label as a multicast label. However, the multicast 108 codepoint has never been deployed, and further development of the 109 procedures for MPLS multicast have shown that, while there is a need 110 for two codepoints, the use of the two codepoints is not properly 111 captured by RFC 3032. 113 In particular, there is no need for the codepoint to indicate whether 114 the top MPLS label is a multicast label. When the receiver of an 115 MPLS packet looks up the top label, the NHLFE will specify whether 116 the label is a multicast label or not. 118 This document updates RFC 3032 and RFC 4023 by re-specifying the use 119 of the codepoints. 121 While RFC 3032 allows an MPLS packet to be carried in an ethernet 122 multicast frame, it fails to specify how the Medium Access Layer 123 Destination Address (MAC DA) field is to be set in that case. This 124 document provides that specification. 126 3. Upstream-Assigned vs. Downstream-Assigned 128 According to RFC 3031 [RFC3031], if two MPLS Label Switching Routers 129 (LSRs) are adjacent in a label switched path (LSP), with respect to 130 that LSP, one of them may be called the "upstream" LSR and the other 131 the "downstream" LSR. Call these Ru and Rd respectively. Before Ru 132 can send an MPLS packet to Rd with label L at the top of the label 133 stack, Ru and Rd must agree on the Forwarding Equivalence Class (FEC) 134 which is bound to L. A particular binding of L to FEC F is called a 135 "downstream-assigned" binding if the binding is first made by Rd and 136 then advertised to Ru. If the binding is first made by Ru and then 137 advertised to Rd, it is called an "upstream-assigned" binding. 139 If Ru and RD are LSP adjacencies, then they transmit a MPLS packet to 140 each other through one of the following mechanisms: 142 1. by putting the MPLS packet in a data link layer frame and 143 transmitting the frame 145 2. by transmitting the MPLS packet through an MPLS tunnel, i.e., 146 by pushing an additional label (or labels) onto the label 147 stack, and then invoking mechanism 1, 149 3. by transmitting the MPLS packet through an IP-based tunnel 150 (e.g., via RFC 4023 [RFC4023]), and then invoking mechanisms 1 151 and/or 2. 153 In short, an MPLS packet is transmitted either through a data link or 154 through an MPLS tunnel or through an IP tunnel. In any of those 155 cases, when the packet emerges through the tunnel, the downstream LSR 156 must know whether the label that now appears at the top of the label 157 stack has an upstream-assigned label binding or a downstream-assigned 158 label binding. For convenience, we will speak of a label with an 159 upstream-assigned label binding as an "upstream-assigned label". 161 Unicast labels MUST be downstream-assigned. 163 Under certain conditions, specified below, multicast labels MAY be 164 upstream-assigned. The ability to use upstream-assigned labels is an 165 OPTIONAL feature. Upstream-assigned labels MUST NOT be used unless 166 it is known that the downstream LSR supports them. How this is known 167 is outside the scope of this document. 169 We discuss three different types of data link or tunnel: 171 - Point-to-Point. A point-to-point data link or tunnel associates 172 two systems, such that transmissions on that link or tunnel made 173 by the one are received by the other, and only by the other. 175 When an MPLS packet is transmitted on a point-to-point data link 176 or tunnel, its top label (before applying the data link or tunnel 177 encapsulation) MUST be a downstream-assigned label. 179 - Point-to-Multipoint. A point-to-multipoint link or tunnel 180 associates n systems, such that only one of them can transmit 181 onto the link or tunnel, and the transmissions may be received by 182 the other n-1 systems. 184 The top labels (before applying the data link or tunnel 185 encapsulation) of all MPLS packets which are transmitted on a 186 particular point-to-multipoint data link or tunnel MUST be of the 187 same type; either all upstream-assigned or all downstream- 188 assigned. This means that all the receivers on the MPLS or IP 189 tunnel must know a priori whether upstream-assigned or 190 downstream-assigned labels are being used in the tunnel. How 191 this is known is outside the scope of this document. 193 - Multipoint-to-Multipoint. A multipoint-to-multipoint link or 194 tunnel associates n systems, such that any of them can transmit 195 on the link or tunnel, and the transmissions may be received by 196 the other n-1 systems. 198 If MPLS packets are transmitted on a particular multipoint-to- 199 multipoint link or tunnel, one of the following scenarios 200 applies: 202 1. It is known (by methods outside the scope of this document) 203 that the top label of every MPLS packet on the link or 204 tunnel is downstream-assigned 206 2. It is known (by methods outside the scope of this document) 207 that the top label of every MPLS packet on the link or 208 tunnel is upstream-assigned 210 3. Some MPLS packets on the link may have upstream-assigned 211 top labels while some may have downstream-assigned top 212 labels 214 If (and only if) the third scenario applies, the data link or 215 tunnel encapsulation MUST provide a codepoint which specifies 216 whether the top label of the encapsulated MPLS packet is 217 upstream-assigned or downstream-assigned. If a particular type 218 of data link or tunnel does not provide such a codepoint, then 219 the third scenario MUST NOT be used. 221 The remainder of this document specifies procedures for setting the 222 data link layer codepoints and address fields. 224 4. Ethernet Codepoints 226 Ethernet is an example of a multipoint-to-multipoint data link. 228 Ethertype 0x8847 is used whenever a unicast ethernet frame carries an 229 MPLS packet. 231 Ethertype 0x8847 is also used whenever a multicast ethernet frame 232 carries an MPLS packet, EXCEPT for the case where the top label of 233 the MPLS packet has been upstream-assigned. 235 Ethertype 0x8848, formerly known as the "MPLS multicast codepoint", 236 is to be used only when an MPLS packet whose top label is upstream- 237 assigned is carried in a multicast ethernet frame. 239 5. PPP Protocol Field 241 PPP is an example of a point-to-point data link. When a PPP frame is 242 carrying an MPLS packet, the PPP Protocol field is always set to 243 0x0281. 245 6. GRE Protocol Type 247 RFC 4023 is modified as described below. 249 If the IP destination address of the GRE encapsulation is a unicast 250 IP address, then the ethertype value 0x8847 MUST be used in all cases 251 for the MPLS-in-GRE encapsulation. 253 If the IP destination address of the GRE encapsulation is a multicast 254 IP address, then: 256 - the ethertype value 0x8847 MUST be used when the top label of the 257 encapsulated MPLS packet is downstream-assigned, 259 - the ethertype value 0x8848 MUST be used when the top label of the 260 encapsulated MPLS packet is upstream-assigned. 262 Through procedures which are outside the scope of this specification, 263 it may be known that if the destination address of a GRE packet is a 264 multicast IP address, then the top label of the GRE payload is 265 upstream-assigned. In such a case, the occurrence of the 8847 266 codepoint in a GRE packet with a multicast destination IP address 267 MUST be considered an error, and the packet MUST be discarded. 269 7. IP Protocol Number 271 RFC 4023 is modified as follows: the IPv4 Protocol Number field or 272 the IPv6 Next Header field is always set to 137, whether or not the 273 encapsulated MPLS packet is an MPLS multicast packet. 275 If the IP destination address of the IP encapsulation is an IP 276 multicast address, the IP tunnel may be considered to be a point-to- 277 multipoint tunnel or a multipoint-to-multipoint tunnel. In either 278 case, either all encapsulated MPLS packets in the particular tunnel 279 have a downstream-assigned label at the top of the stack, or all 280 encapsulated MPLS packets in that tunnel have an upstream-assigned 281 label at the top of the stack. The means by which this is determined 282 for a particular tunnel is outside the scope of this specification. 284 8. Ethernet MAC DA for Multicast MPLS 286 When an LSR transmits a multicast MPLS packet in a multicast ethernet 287 frame, it MUST set the Destination MAC Address to the value 01-00- 288 5e-8a-bc-de, where abcde MUST, by default, be the twenty-bit (five- 289 nibble) value of the second MPLS label on the packet's label stack. 290 By "the second label", we mean the label that is in the label stack 291 entry that immediately follows the topmost label stack entry. The 292 LSR MAY, if configured to do so, allow a a label other than the 293 second to be used for this purpose. 295 It is expected that the LSR will follow the procedures of [UPSTREAM], 296 pushing on two labels, with the topmost label being a "context label" 297 that is the same for all MPLS packets being transmitted by the LSR 298 onto the ethernet, but with the second label being different for 299 different LSPs. Thus if the MAC DA value is a function of the second 300 label, more of the LSP-specific information about the packet appears 301 in the MAC DA field. However, the way in which that information is 302 used, if any, is outside the scope of this document. 304 9. IANA Considerations 306 IANA already owns the set of ethernet multicast addresses in the 307 range 01-00-5e-00-00-00 to 01-00-5e-ff-ff-ff. Addresses in the range 308 01-00-5e-00-00-00 to 01-00-5e-7f-ff-ff are reserved for use when an 309 ethernet multicast frame carries an IP multicast packet. IANA shall 310 reserve ethernet addresses in the range 01-00-5e-80-00-00 to 01-00- 311 5e-8f-ff-ff for use when an ethernet multicast frame carries an MPLS 312 multicast packet. 314 10. Security Considerations 316 The security considerations of RFC 3032 and RFC 4023 apply. 318 Malicious changing of the codepoint may result in loss or misrouting 319 of packets. However, altering the codepoint without also altering the 320 label does not result in a predictable effect. 322 Malicious alteration of the MAC DA on an ethernet can result in 323 packets being received by a third party, rather than by the intended 324 recipient. 326 11. Normative References 328 [RFC2119] "Key words for use in RFCs to Indicate Requirement 329 Levels.", Bradner, March 1997 331 [RFC3031] "Multiprotocol Label Switching Architecture", Rosen, 332 Viswanathan, Callon, January 2001 334 [RFC3032] "MPLS Label Stack Encoding", Rosen, et. al., January 2001 336 [RFC4023] "Encapsulating MPLS in IP or GRE", Worster, Rekhter, Rosen, 337 March 2005 339 12. Informative References 341 [UPSTREAM] "MPLS Upstream Label Assignment and Context Specific Label 342 Space", Aggarwal, Rekhter, Rosen, draft-ietf-mpls-upstream-label- 343 02.txt, March 2007. 345 13. Authors' Addresses 347 Toerless Eckert 348 Cisco Systems, Inc. 349 170 Tasman Drive 350 San Jose, CA, 95134 351 Email: eckert@cisco.com 353 Eric C. Rosen 354 Cisco Systems, Inc. 355 1414 Massachusetts Avenue 356 Boxborough, MA 01719 357 Email: erosen@cisco.com 359 Rahul Aggarwal 360 Juniper Networks 361 1194 North Mathilda Ave. 362 Sunnyvale, CA 94089 363 Email: rahul@juniper.net 365 Yakov Rekhter 366 Juniper Networks 367 1194 North Mathilda Ave. 368 Sunnyvale, CA 94089 369 Email: yakov@juniper.net 371 14. Full Copyright Statement 373 Copyright (C) The IETF Trust (2007). 375 This document is subject to the rights, licenses and restrictions 376 contained in BCP 78, and except as set forth therein, the authors 377 retain all their rights. 379 This document and the information contained herein are provided on an 380 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 381 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND 382 THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS 383 OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF 384 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 385 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 387 15. Intellectual Property 389 The IETF takes no position regarding the validity or scope of any 390 Intellectual Property Rights or other rights that might be claimed to 391 pertain to the implementation or use of the technology described in 392 this document or the extent to which any license under such rights 393 might or might not be available; nor does it represent that it has 394 made any independent effort to identify any such rights. Information 395 on the procedures with respect to rights in RFC documents can be 396 found in BCP 78 and BCP 79. 398 Copies of IPR disclosures made to the IETF Secretariat and any 399 assurances of licenses to be made available, or the result of an 400 attempt made to obtain a general license or permission for the use of 401 such proprietary rights by implementers or users of this 402 specification can be obtained from the IETF on-line IPR repository at 403 http://www.ietf.org/ipr. 405 The IETF invites any interested party to bring to its attention any 406 copyrights, patents or patent applications, or other proprietary 407 rights that may cover technology that may be required to implement 408 this standard. Please address the information to the IETF at ietf- 409 ipr@ietf.org.