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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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-11) exists of draft-ietf-bfd-seamless-base-08 -- Obsolete informational reference (is this intentional?): RFC 2460 (Obsoleted by RFC 8200) Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Internet Engineering Task Force N. Akiya 3 Internet-Draft Big Switch Networks 4 Intended status: Standards Track C. Pignataro 5 Expires: October 15, 2016 D. Ward 6 Cisco Systems 7 April 13, 2016 9 Seamless Bidirectional Forwarding Detection (S-BFD) for 10 IPv4, IPv6 and MPLS 11 draft-ietf-bfd-seamless-ip-04 13 Abstract 15 This document defines procedures to use Seamless Bidirectional 16 Forwarding Detection (S-BFD) for IPv4, IPv6 and MPLS environments. 18 Requirements Language 20 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 21 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 22 document are to be interpreted as described in RFC 2119 [RFC2119]. 24 Status of This Memo 26 This Internet-Draft is submitted in full conformance with the 27 provisions of BCP 78 and BCP 79. 29 Internet-Drafts are working documents of the Internet Engineering 30 Task Force (IETF). Note that other groups may also distribute 31 working documents as Internet-Drafts. The list of current Internet- 32 Drafts is at http://datatracker.ietf.org/drafts/current/. 34 Internet-Drafts are draft documents valid for a maximum of six months 35 and may be updated, replaced, or obsoleted by other documents at any 36 time. It is inappropriate to use Internet-Drafts as reference 37 material or to cite them other than as "work in progress." 39 This Internet-Draft will expire on October 15, 2016. 41 Copyright Notice 43 Copyright (c) 2016 IETF Trust and the persons identified as the 44 document authors. All rights reserved. 46 This document is subject to BCP 78 and the IETF Trust's Legal 47 Provisions Relating to IETF Documents 48 (http://trustee.ietf.org/license-info) in effect on the date of 49 publication of this document. Please review these documents 50 carefully, as they describe your rights and restrictions with respect 51 to this document. Code Components extracted from this document must 52 include Simplified BSD License text as described in Section 4.e of 53 the Trust Legal Provisions and are provided without warranty as 54 described in the Simplified BSD License. 56 Table of Contents 58 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 59 2. S-BFD UDP Port . . . . . . . . . . . . . . . . . . . . . . . 2 60 3. S-BFD Echo UDP Port . . . . . . . . . . . . . . . . . . . . . 3 61 4. S-BFD Control Packet Demultiplexing . . . . . . . . . . . . . 3 62 5. Initiator Procedures . . . . . . . . . . . . . . . . . . . . 3 63 5.1. Details of S-BFD Control Packet Sent by SBFDInitiator . . 4 64 5.1.1. Target vs. Remote Entity (S-BFD Discriminator) . . . 4 65 6. Responder Procedures . . . . . . . . . . . . . . . . . . . . 5 66 6.1. Details of S-BFD Control Packet Sent by SBFDReflector . . 5 67 7. Security Considerations . . . . . . . . . . . . . . . . . . . 5 68 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 69 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 70 10. Contributing Authors . . . . . . . . . . . . . . . . . . . . 6 71 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 72 11.1. Normative References . . . . . . . . . . . . . . . . . . 7 73 11.2. Informative References . . . . . . . . . . . . . . . . . 7 74 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 76 1. Introduction 78 Seamless Bidirectional Forwarding Detection (S-BFD), 79 [I-D.ietf-bfd-seamless-base], defines a generalized mechanism to 80 allow network nodes to seamlessly perform continuity checks to remote 81 entities. This document defines necessary procedures to use S-BFD on 82 IPv4, IPv6 and MPLS environments. 84 The reader is expected to be familiar with the IP [RFC0791] 85 [RFC2460], BFD [RFC5880], MPLS BFD [RFC5884], and S-BFD 86 [I-D.ietf-bfd-seamless-base] terminologies and protocol constructs. 88 2. S-BFD UDP Port 90 A new UDP port is defined for the use of the S-BFD on IPv4, IPv6 and 91 MPLS environments: 7784. SBFDReflector session MUST listen for 92 incoming S-BFD control packets on the port 7784. SBFDInitiator 93 sessions MUST transmit S-BFD control packets with destination port 94 7784. The source port of the S-BFD control packets transmitted by 95 SBFDInitiator sessions can be any but MUST NOT be 7784. The same UDP 96 source port number MUST be used for all S-BFD control packets 97 associated with a particular SBFDInitiator session. The source port 98 number is unique among all SBFDInitiator sessions on the system. 100 3. S-BFD Echo UDP Port 102 The BFD Echo port defined by [RFC5881], port 3785, is used for the 103 S-BFD Echo function on IPv4, IPv6 and MPLS environments. 104 SBFDInitiator sessions MUST transmit S-BFD echo packets with 105 destination port 3785. This document defines only the UDP port value 106 for the S-BFD Echo function. The source port and the procedures for 107 the S-BFD Echo function are outside the scope of this document. 109 4. S-BFD Control Packet Demultiplexing 111 The S-BFD Control Packet demultiplexing follows the procedure 112 specified in Section 7.1. of [I-D.ietf-bfd-seamless-base]. Received 113 S-BFD control packet MUST be demultiplexed with the destination UDP 114 port field. 116 This procedure for an S-BFD packet is executed on both the initiator 117 and the reflector. If the port is 7784 (i.e., S-BFD packet for 118 S-BFDReflector)), then the packet MUST be looked up to locate a 119 corresponding SBFDReflector session based on the value from the "your 120 discriminator" field in the table describing S-BFD discriminators. 121 If the port is not 7784, then the packet MUST be looked up to locate 122 a corresponding SBFDInitiator session or classical BFD session based 123 on the value from the "your discriminator" field in the table 124 describing BFD discriminators. If the located session is an 125 SBFDInitiator, then the destination IP address of the packet SHOULD 126 be validated to be for self. If the packet is a classical BFD 127 session, then the procedures from [RFC5880] apply. 129 5. Initiator Procedures 131 S-BFD control packets are transmitted with IP header, UDP header and 132 BFD control header ([RFC5880]). When S-BFD control packets are 133 explicitly label switched (i.e. not IP routed which happen to go over 134 an LSP, but explicitly sent on a specific LSP), the former is 135 prepended with a label stack. Note that this document does not make 136 a distinction between a single-hop S-BFD scenario and a multi-hop 137 S-BFD scenario, both scenarios are supported. 139 Necessary values in the BFD control headers are described in 140 [I-D.ietf-bfd-seamless-base]. Section 5.1 describes necessary values 141 in the MPLS header, IP header and UDP header when an SBFDInitiator on 142 the initiator is sending S-BFD control packets. 144 5.1. Details of S-BFD Control Packet Sent by SBFDInitiator 146 o Specifications common to both IP routed S-BFD control packets and 147 explicitly label switched S-BFD control packets: 149 * Source IP address field of the IP header MUST be set to a local 150 IP address that is expected to be routable by the target (i.e. 151 not IPv6 link-local address when the target is multiple hops 152 away). 154 * UDP destination port MUST be set to a well-known UDP 155 destination port assigned for S-BFD: 7784. 157 * UDP source port MUST NOT be set to 7784. 159 o Specifications for IP routed S-BFD control packets: 161 * Destination IP address field of the IP header MUST set to an IP 162 address of the target. 164 * TTL field of the IP header SHOULD be set to 255. 166 o Specifications for explicitly label switched S-BFD control 167 packets: 169 * S-BFD control packets MUST have the label stack that is 170 expected to reach the target. 172 * TTL field of the top most label SHOULD be 255. 174 * The destination IP address MUST be chosen from the 127/8 range 175 for IPv4 and from the 0:0:0:0:0:FFFF:7F00/104 range for IPv6, 176 as with [RFC5884]. 178 * TTL field of the IP header MUST be set to 1. 180 5.1.1. Target vs. Remote Entity (S-BFD Discriminator) 182 Typically, an S-BFD control packet will have "your discriminator" 183 field corresponding to an S-BFD discriminator of the remote entity 184 located on the target network node defined by the destination IP 185 address or the label stack. It is, however, possible for an 186 SBFDInitiator to carefully set "your discriminator" and TTL fields to 187 perform a continuity test towards a target, but to a transit network 188 node and not to the target itself. 190 Section 5.1 intentionally uses the word "target", instead of "remote 191 entity", to accommodate this possible S-BFD usage through TTL expiry. 193 This also requires S-BFD control packets not be dropped by the 194 responder node due to TTL expiry. Thus implementations on the 195 responder MUST allow received S-BFD control packets taking TTL expiry 196 exception path to reach corresponding reflector BFD session. 198 6. Responder Procedures 200 S-BFD control packets are IP routed back to the initiator, and will 201 have IP header, UDP header and BFD control header. If an 202 SBFDReflector receives an S-BFD control packet with UDP source port 203 as 7784, the packet MUST be discarded. Necessary values in the BFD 204 control header are described in [I-D.ietf-bfd-seamless-base]. 205 Section 6.1 describes necessary values in the IP header and UDP 206 header when an SBFDReflector on the responder is sending S-BFD 207 control packets. 209 6.1. Details of S-BFD Control Packet Sent by SBFDReflector 211 o Destination IP address field of the IP header MUST be copied from 212 source IP address field of received S-BFD control packet. 214 o Source IP address field of the IP header MUST be set to a local IP 215 address that is expected to be visible by the initiator (i.e. not 216 IPv6 link-local address when the initiator is multiple hops away). 217 The source IP address SHOULD be copied from the destination IP 218 address field of the received S-BFD control packet, except when it 219 is from the 127/8 range for IPv4 or from the 220 0:0:0:0:0:FFFF:7F00/104 range for IPv6. 222 o TTL field of the IP header MUST be set to 255. 224 o UDP destination port MUST be copied from received UDP source port. 226 o UDP source port MUST be copied from received UDP destination port. 228 7. Security Considerations 230 Security considerations for S-BFD are discussed in 231 [I-D.ietf-bfd-seamless-base]. Additionally, implementing the 232 following measures will strengthen security aspects of the mechanism 233 described by this document: 235 o Implementations MUST provide filtering capability based on source 236 IP addresses of received S-BFD control packets: [RFC2827]. 238 o Implementations MUST NOT act on received S-BFD control packets 239 containing source Martian IP addresses (i.e., address that, by 240 application of the current forwarding tables, would not have its 241 return traffic routed back to the sender.) 243 o Implementations MUST ensure that response S-BFD control packets 244 generated to the initiator by the SBFDReflector have a reachable 245 target (ex: destination IP address). 247 8. IANA Considerations 249 A new value 7784 was allocated from the "Service Name and Transport 250 Protocol Port Number Registry". The allocated registry entry is: 252 Service Name (REQUIRED) 253 s-bfd 254 Transport Protocol(s) (REQUIRED) 255 udp 256 Assignee (REQUIRED) 257 IESG 258 Contact (REQUIRED) 259 BFD Chairs 260 Description (REQUIRED) 261 Seamless Bidirectional Forwarding Detection (S-BFD) 262 Reference (REQUIRED) 263 RFC.this (RFC Editor, please update at publication) 264 Port Number (OPTIONAL) 265 7784 267 9. Acknowledgements 269 The authors would like to thank the BFD WG members for helping to 270 shape the contents of this document. In particular, significant 271 contributions were made by following people: Marc Binderberger, 272 Jeffrey Haas, Santosh Pallagatti, Greg Mirsky, Sam Aldrin, Vengada 273 Prasad Govindan, Mallik Mudigonda and Srihari Raghavan. 275 10. Contributing Authors 277 Tarek Saad 278 Cisco Systems 279 Email: tsaad@cisco.com 281 Siva Sivabalan 282 Cisco Systems 283 Email: msiva@cisco.com 285 Nagendra Kumar 286 Cisco Systems 287 Email: naikumar@cisco.com 289 11. References 291 11.1. Normative References 293 [I-D.ietf-bfd-seamless-base] 294 Akiya, N., Pignataro, C., Ward, D., Bhatia, M., and J. 295 Networks, "Seamless Bidirectional Forwarding Detection 296 (S-BFD)", draft-ietf-bfd-seamless-base-08 (work in 297 progress), February 2016. 299 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 300 Requirement Levels", BCP 14, RFC 2119, 301 DOI 10.17487/RFC2119, March 1997, 302 . 304 [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection 305 (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010, 306 . 308 [RFC5881] Katz, D. and D. Ward, "Bidirectional Forwarding Detection 309 (BFD) for IPv4 and IPv6 (Single Hop)", RFC 5881, 310 DOI 10.17487/RFC5881, June 2010, 311 . 313 11.2. Informative References 315 [RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, 316 DOI 10.17487/RFC0791, September 1981, 317 . 319 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 320 (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460, 321 December 1998, . 323 [RFC2827] Ferguson, P. and D. Senie, "Network Ingress Filtering: 324 Defeating Denial of Service Attacks which employ IP Source 325 Address Spoofing", BCP 38, RFC 2827, DOI 10.17487/RFC2827, 326 May 2000, . 328 [RFC5884] Aggarwal, R., Kompella, K., Nadeau, T., and G. Swallow, 329 "Bidirectional Forwarding Detection (BFD) for MPLS Label 330 Switched Paths (LSPs)", RFC 5884, DOI 10.17487/RFC5884, 331 June 2010, . 333 Authors' Addresses 335 Nobo Akiya 336 Big Switch Networks 338 Email: nobo.akiya.dev@gmail.com 340 Carlos Pignataro 341 Cisco Systems 343 Email: cpignata@cisco.com 345 Dave Ward 346 Cisco Systems 348 Email: wardd@cisco.com