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(See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (January 31, 2007) is 6295 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) ** Obsolete normative reference: RFC 2434 (Obsoleted by RFC 5226) Summary: 2 errors (**), 0 flaws (~~), 1 warning (==), 8 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 MPLS Working Group R. Bonica 3 Internet-Draft D. Gan 4 Intended status: Standards Track Juniper Networks 5 Expires: August 4, 2007 D. Tappan 6 C. Pignataro 7 Cisco Systems, Inc. 8 January 31, 2007 10 ICMP Extensions for MultiProtocol Label Switching 11 draft-ietf-mpls-icmp-08 13 Status of this Memo 15 By submitting this Internet-Draft, each author represents that any 16 applicable patent or other IPR claims of which he or she is aware 17 have been or will be disclosed, and any of which he or she becomes 18 aware will be disclosed, in accordance with Section 6 of BCP 79. 20 Internet-Drafts are working documents of the Internet Engineering 21 Task Force (IETF), its areas, and its working groups. Note that 22 other groups may also distribute working documents as Internet- 23 Drafts. 25 Internet-Drafts are draft documents valid for a maximum of six months 26 and may be updated, replaced, or obsoleted by other documents at any 27 time. It is inappropriate to use Internet-Drafts as reference 28 material or to cite them other than as "work in progress." 30 The list of current Internet-Drafts can be accessed at 31 http://www.ietf.org/ietf/1id-abstracts.txt. 33 The list of Internet-Draft Shadow Directories can be accessed at 34 http://www.ietf.org/shadow.html. 36 This Internet-Draft will expire on August 4, 2007. 38 Copyright Notice 40 Copyright (C) The IETF Trust (2007). 42 Abstract 44 This memo defines an extension object that can be appended to 45 selected multi-part ICMP messages. This extension permits Label 46 Switching Routers to append MPLS information to ICMP messages, and 47 has already been widely deployed. 49 Table of Contents 51 1. Conventions Used In This Document . . . . . . . . . . . . . . . 3 52 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 53 3. Application to TRACEROUTE . . . . . . . . . . . . . . . . . . . 4 54 4. Disclaimer . . . . . . . . . . . . . . . . . . . . . . . . . . 4 55 5. MPLS Label Stack Object . . . . . . . . . . . . . . . . . . . . 5 56 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 57 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 58 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 59 8.1. Normative References . . . . . . . . . . . . . . . . . . . 7 60 8.2. Informative References . . . . . . . . . . . . . . . . . . 7 61 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7 62 Intellectual Property and Copyright Statements . . . . . . . . . . 9 64 1. Conventions Used In This Document 66 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 67 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 68 document are to be interpreted as described in RFC2119 [RFC2119]. 70 2. Introduction 72 IP routers use the Internet Control Message Protocol, ICMPv4 73 [RFC0792] and ICMPv6 [RFC4443], to convey control information to 74 source hosts. Network operators use this information to diagnose 75 routing problems. 77 When a router receives an undeliverable IP datagram, it can send an 78 ICMP message to the host that originated the datagram. The ICMP 79 message indicates why the datagram could not be delivered. It also 80 contains the IP header and leading payload octets of the "original 81 datagram" to which the ICMP message is a response. 83 MPLS Label Switching Routers (LSR) also use ICMP to convey control 84 information to source hosts. Section 2.3 of [RFC3032] describes the 85 interaction between MPLS and ICMP, and Sections 2.4 and 3 of 86 [RFC3032] provide applications of that interaction. 88 When an LSR receives an undeliverable MPLS encapsulated datagram, it 89 removes the entire MPLS label stack, exposing the previously 90 encapsulated IP datagram. The LSR then submits the IP datagram to an 91 error processing module. Error processing can include ICMP message 92 generation. 94 The ICMP message indicates why the original datagram could not be 95 delivered. It also contains the IP header and leading octets of the 96 original datagram. 98 The ICMP message, however, contains no information regarding the MPLS 99 label stack that encapsulated the original datagram when it arrived 100 at the LSR. This omission is significant because the LSR would have 101 forwarded the original datagram based upon information contained by 102 the MPLS label stack. 104 This memo defines an ICMP extension object that permits an LSR to 105 append MPLS information to ICMP messages. Selected ICMP messages 106 SHOULD include the MPLS label stack, as it arrived at the router that 107 is sending the ICMP message. The ICMP message MUST also include the 108 IP header and leading payload octets of the original datagram. 110 The ICMP extensions defined in this document must be preceded by an 111 ICMP Extension Structure Header and an ICMP Object Header. Both are 112 defined in [I-D.bonica-internet-icmp]. 114 The ICMP extension defined in this document is equally applicable to 115 ICMPv4 [RFC0792] and ICMPv6 [RFC4443]. Throughout this document, 116 unless otherwise specified, the acronym ICMP refers to multi-part 117 ICMP messages, encompassing both ICMPv4 and ICMPv6. 119 3. Application to TRACEROUTE 121 The ICMP extension defined in this memo supports enhancements to 122 TRACEROUTE. Enhanced TRACEROUTE applications, like older 123 implementations, indicate which nodes the original datagram visited 124 en route to its destination. They differ from older implementations 125 in that they also reflect the original datagram's MPLS encapsulation 126 status as it arrived at each node. 128 Figure 1 contains sample output from an enhanced TRACEROUTE 129 implementation. 131 > traceroute 192.0.2.1 133 traceroute to 192.0.2.1 (192.0.2.1), 30 hops max, 40 byte packets 135 1 192.0.2.13 (192.0.2.13) 0.661 ms 0.618 ms 0.579 ms 137 2 192.0.2.9 (192.0.2.9) 0.861 ms 0.718 ms 0.679 ms 139 MPLS Label=100048 Exp=0 TTL=1 S=1 141 3 192.0.2.5 (192.0.2.5) 0.822 ms 0.731 ms 0.708 ms 143 MPLS Label=100016 Exp=0 TTL=1 S=1 145 4 192.0.2.1 (192.0.2.1) 0.961 ms 8.676 ms 0.875 ms 147 Figure 1: Enhanced TRACEROUTE Sample Output 149 4. Disclaimer 151 This memo does not define the general relationship between ICMP and 152 MPLS. Section 2.3 of [RFC3032] defines this relationship. 154 The current memo does not define encapsulation specific TTL 155 manipulation procedures. It defers to Section 5.4 of RFC 3034 156 [RFC3034] and Section 10 of [RFC3035] in this matter. 158 When encapsulation specific TTL manipulation procedures defeat the 159 basic TRACEROUTE mechanism, they will also defeat enhanced TRACEROUTE 160 implementations. 162 5. MPLS Label Stack Object 164 The MPLS Label Stack Object can be appended to the ICMP Time Exceeded 165 and Destination Unreachable messages. A single instance of the MPLS 166 Label Stack Object represents the entire MPLS label stack, formatted 167 exactly as it was when it arrived at the LSR that sends the ICMP 168 message. 170 Figure 2 depicts the MPLS Label Stack Object. It must be preceded by 171 an ICMP Extension Structure Header and an ICMP Object Header. Both 172 are defined in [I-D.bonica-internet-icmp]. 174 In the object payload, octets 0-3 depict the first member of the MPLS 175 label stack. Each remaining member of the MPLS label stack is 176 represented by another 4 octets that share the same format. 178 Class-Num = 1, MPLS Label Stack Class 179 C-Type = 1, Incoming MPLS Label Stack 180 Length = 4 + 4 * (number of MPLS LSEs) 182 0 1 2 3 183 +-------------+-------------+-------------+-------------+ 184 | Label |EXP |S| TTL | 185 +-------------+-------------+-------------+-------------+ 186 | | 187 | // Remaining MPLS Label Stack Entries // | 188 | | 189 +-------------+-------------+-------------+-------------+ 191 Figure 2: MPLS Label Stack Object 193 Label: 20 bits 195 Exp: Experimental Use, 3 bits 197 S: Bottom of Stack, 1 bit 198 TTL: Time to Live, 8 bits 200 6. Security Considerations 202 This memo does not specify the conditions that trigger the generation 203 of ICMP Messages for Labeled IP Packets. It does not define the 204 interaction between MPLS and ICMP. However, this document defines an 205 extension that allows an MPLS router to append MPLS information to 206 multi-part ICMP messages, and therefore can provide the user of the 207 traceroute application with additional information. Consequently, a 208 network operator may wish to provide this information selectively 209 based on some policy; for example, only include the MPLS extensions 210 in ICMP messages destined to addresses within the network management 211 blocks with administrative control over the router. An 212 implementation could determine whether to include the MPLS Label 213 Stack extensions based upon the destination address of the ICMP 214 message, or based on a global configuration option in the router. 215 Alternatively, an implementation may determine whether to include 216 these MPLS extensions when TTL expires based on the number of label 217 stack entries (depth of the label stack) of the incoming packet. 218 Finally, an operator can make use of the TTL treatment on MPLS Pipe 219 Model LSPs defined in [RFC3443] for a TTL-transparent mode of 220 operation, that would prevent ICMP Time Exceeded altogether when 221 tunneled over the MPLS LSP. 223 7. IANA Considerations 225 IANA is requested to assign the following object Class-num in the 226 ICMP Extension Object registry: 228 Class-Num Description 229 1 MPLS Label Stack Class 231 IANA is also requested to establish a registry for the corresponding 232 class sub-type (C-Type) space, as follows: 234 MPLS Label Stack Class Sub-types: 236 C-Type Description 237 1 Incoming MPLS Label Stack 238 0xF7-0xFF Reserved for private use 240 C-Type values are assignable on a first-come-first-serve (FCFS) basis 241 [RFC2434]. 243 8. References 245 8.1. Normative References 247 [I-D.bonica-internet-icmp] 248 Bonica, R., "Extended ICMP to Support Multi-part 249 Messages", draft-bonica-internet-icmp-16 (work in 250 progress), January 2007. 252 [RFC0792] Postel, J., "Internet Control Message Protocol", STD 5, 253 RFC 792, September 1981. 255 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 256 Requirement Levels", BCP 14, RFC 2119, March 1997. 258 [RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an 259 IANA Considerations Section in RFCs", BCP 26, RFC 2434, 260 October 1998. 262 [RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y., 263 Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack 264 Encoding", RFC 3032, January 2001. 266 [RFC4443] Conta, A., Deering, S., and M. Gupta, "Internet Control 267 Message Protocol (ICMPv6) for the Internet Protocol 268 Version 6 (IPv6) Specification", RFC 4443, March 2006. 270 8.2. Informative References 272 [RFC3034] Conta, A., Doolan, P., and A. Malis, "Use of Label 273 Switching on Frame Relay Networks Specification", 274 RFC 3034, January 2001. 276 [RFC3035] Davie, B., Lawrence, J., McCloghrie, K., Rosen, E., 277 Swallow, G., Rekhter, Y., and P. Doolan, "MPLS using LDP 278 and ATM VC Switching", RFC 3035, January 2001. 280 [RFC3443] Agarwal, P. and B. Akyol, "Time To Live (TTL) Processing 281 in Multi-Protocol Label Switching (MPLS) Networks", 282 RFC 3443, January 2003. 284 Authors' Addresses 286 Ronald P. Bonica 287 Juniper Networks 288 2251 Corporate Park Drive 289 Herndon, VA 20171 290 US 292 Email: rbonica@juniper.net 294 Der-Hwa Gan 295 Juniper Networks 296 1194 N. Mathilda Ave. 297 Sunnyvale, CA 94089 298 US 300 Email: dhg@juniper.net 302 Daniel C. Tappan 303 Cisco Systems, Inc. 304 250 Apollo Drive 305 Chelmsford, MA 01824 306 US 308 Email: dan.tappan@gmail.com 310 Carlos Pignataro 311 Cisco Systems, Inc. 312 7025 Kit Creek Road 313 Research Triangle Park, N.C. 27709 314 US 316 Email: cpignata@cisco.com 318 Full Copyright Statement 320 Copyright (C) The IETF Trust (2007). 322 This document is subject to the rights, licenses and restrictions 323 contained in BCP 78, and except as set forth therein, the authors 324 retain all their rights. 326 This document and the information contained herein are provided on an 327 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 328 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND 329 THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS 330 OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF 331 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 332 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 334 Intellectual Property 336 The IETF takes no position regarding the validity or scope of any 337 Intellectual Property Rights or other rights that might be claimed to 338 pertain to the implementation or use of the technology described in 339 this document or the extent to which any license under such rights 340 might or might not be available; nor does it represent that it has 341 made any independent effort to identify any such rights. Information 342 on the procedures with respect to rights in RFC documents can be 343 found in BCP 78 and BCP 79. 345 Copies of IPR disclosures made to the IETF Secretariat and any 346 assurances of licenses to be made available, or the result of an 347 attempt made to obtain a general license or permission for the use of 348 such proprietary rights by implementers or users of this 349 specification can be obtained from the IETF on-line IPR repository at 350 http://www.ietf.org/ipr. 352 The IETF invites any interested party to bring to its attention any 353 copyrights, patents or patent applications, or other proprietary 354 rights that may cover technology that may be required to implement 355 this standard. Please address the information to the IETF at 356 ietf-ipr@ietf.org. 358 Acknowledgment 360 Funding for the RFC Editor function is provided by the IETF 361 Administrative Support Activity (IASA).