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If these are generic example addresses, they should be changed to use the 233.252.0.x range defined in RFC 5771 Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (October 28, 2020) is 1275 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) -- Possible downref: Non-RFC (?) normative reference: ref. 'IEEE.802.1AX.2008' Summary: 0 errors (**), 0 flaws (~~), 3 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 RTG Working Group G. Mirsky 3 Internet-Draft ZTE Corp. 4 Intended status: Standards Track J. Tantsura 5 Expires: May 1, 2021 Apstra 6 G. Mishra 7 Verizon Inc. 8 October 28, 2020 10 Bidirectional Forwarding Detection (BFD) on Multi-chassis Link 11 Aggregation Group (MC-LAG) Interfaces 12 draft-mtm-rtgwg-bfd-mc-lag-00 14 Abstract 16 This document describes the use of Bidirectional Forwarding Detection 17 for Multi-chassis Link Aggregation Group to provide faster than Link 18 Aggregation Control Protocol convergence. This specification 19 enhances RFC 7130 "Bidirectional Forwarding Detection (BFD) on Link 20 Aggregation Group (LAG) Interfaces". 22 Status of This Memo 24 This Internet-Draft is submitted in full conformance with the 25 provisions of BCP 78 and BCP 79. 27 Internet-Drafts are working documents of the Internet Engineering 28 Task Force (IETF). Note that other groups may also distribute 29 working documents as Internet-Drafts. The list of current Internet- 30 Drafts is at https://datatracker.ietf.org/drafts/current/. 32 Internet-Drafts are draft documents valid for a maximum of six months 33 and may be updated, replaced, or obsoleted by other documents at any 34 time. It is inappropriate to use Internet-Drafts as reference 35 material or to cite them other than as "work in progress." 37 This Internet-Draft will expire on May 1, 2021. 39 Copyright Notice 41 Copyright (c) 2020 IETF Trust and the persons identified as the 42 document authors. All rights reserved. 44 This document is subject to BCP 78 and the IETF Trust's Legal 45 Provisions Relating to IETF Documents 46 (https://trustee.ietf.org/license-info) in effect on the date of 47 publication of this document. Please review these documents 48 carefully, as they describe your rights and restrictions with respect 49 to this document. Code Components extracted from this document must 50 include Simplified BSD License text as described in Section 4.e of 51 the Trust Legal Provisions and are provided without warranty as 52 described in the Simplified BSD License. 54 Table of Contents 56 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 57 1.1. Conventions used in this document . . . . . . . . . . . . 2 58 1.1.1. Acronyms . . . . . . . . . . . . . . . . . . . . . . 2 59 1.1.2. Requirements Language . . . . . . . . . . . . . . . . 3 60 2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3 61 3. BFD on MC-LAG with IP-only Data Plane . . . . . . . . . . . . 3 62 4. BFD on MC-LAG with IP/MPLS Data Plane . . . . . . . . . . . . 4 63 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 64 6. Security Considerations . . . . . . . . . . . . . . . . . . . 5 65 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 66 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 67 8.1. Normative References . . . . . . . . . . . . . . . . . . 5 68 8.2. Informative . . . . . . . . . . . . . . . . . . . . . . . 6 69 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 71 1. Introduction 73 The [RFC7130] defines the use of Bidirectional Forwarding Detection 74 (BFD) on Link Aggregation Group (LAG) interfaces. A multi-chassis 75 LAG (MC-LAG) is a type of LAG [IEEE.802.1AX.2008] with member links 76 terminated on separate chassis. [IEEE.802.1AX.2008] does not specify 77 MC-LAG but doesn't preclude it either. Link Aggregation Control 78 Protocol (LACP), also defined in [IEEE.802.1AX.2008], can work with 79 MC-LAG but, as in the LAG case, the fastest link failure detection 80 interval is only in a range of single-digit seconds. This document 81 defines how the mechanism defined to work on LAG interfaces [RFC7130] 82 can be adapted to the MC-LAG case to enable sub-second detection of 83 member link failure. 85 1.1. Conventions used in this document 87 1.1.1. Acronyms 89 ACH: Associated Channel Header 91 BFD: Bidirectional Forwarding Detection 93 BoS: Bottom of the Stack 95 G-ACh: Generic Associated Channel 96 GAL: Generic Associated Label 98 LAG: Link Aggregation Group 100 LACP: Link Aggregation Control Protocol 102 MC-LAG: Multi-chassis Link Aggregation Group 104 MPLS: Multi-Protocol Label Switching 106 1.1.2. Requirements Language 108 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 109 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 110 "OPTIONAL" in this document are to be interpreted as described in BCP 111 14 [RFC2119] [RFC8174] when, and only when, they appear in all 112 capitals, as shown here. 114 2. Problem Statement 116 [RFC7130] does not specify the selection of the destination IP 117 address for the BFD control packet. The only requirement related to 118 the selection is in Section 2.1, stating that the use of the address 119 family across all member links of the given LAG MUST be consistent 120 across all the links. Thus it is implied that the same unicast IP 121 address will be used on all member links of the LAG as the use of 122 different destination addresses would defeat the purpose of [RFC7130] 123 transforming the case into a set of single-hop BFD sessions 124 [RFC5881]. But a single unicast IP address may not work in the MC- 125 LAG case as the member links are terminated on the separate chassis. 126 This document proposes how to overcome this problem if using IP or 127 Multi-Protocol Label Switching (MPLS) data plane encapsulation. 129 3. BFD on MC-LAG with IP-only Data Plane 131 As described in [RFC7130], a micro-BFD session on the LAG interfaces 132 may use IPv4 or IPv6 address family. In some cases, two sessions, 133 one with IPv4 and one with IPv6 addresses, may run concurrently. 134 This document doesn't change any of these but specifies the selection 135 of the destination IP address in the MC-LAG use case: 137 o if IPv4 address family is used for the micro-BFD session, then an 138 address from the link-local multicast address 224.0.0.0/24 range 139 SHOULD be used as the destination IP address. The subnet 140 broadcast address MAY be used as the destination IP address as 141 well; 143 o if the address family used is IPv6, then the IPv6 All Routers 144 address with the link scope, as defined in [RFC4291], FF02::2/128 145 MUST be used as the destination IP address. 147 4. BFD on MC-LAG with IP/MPLS Data Plane 149 There are more optional encapsulation formats for the case of micro- 150 BFD on MC-LAG over IP/MPLS data plane: 152 o [RFC5586] defined the special-purpose Generic Associated channel 153 Label (GAL) that MAY be used in MPLS encapsulation of the micro- 154 BFD control packet over the MPSL data plane. Depending on the 155 channel type specified in the Associated Channel Header (ACH) that 156 immediately follows after the GAL, micro-BFD MAY use IP/UDP, as 157 displayed in Figure 1 or BFD format, i.e., BFD control packet 158 without IP and UDP headers. 160 0 1 2 3 161 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 1 162 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 163 | GAL | TC |1| TTL | 164 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 165 |0 0 0 1|0 0 0 0| Reserved | IPv4 channel (0x0021) | 166 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 167 | | 168 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 169 | | 170 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 171 | Destination IP address | 172 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 173 | Source IP address | 174 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 175 | UDP header | 176 | | 177 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 178 ~ BFD Control Packet ~ 179 | | 180 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 182 Figure 1: BFD on MC-LAG member link on IPv4/MPLS data plane 184 If the IP/UDP format of BFD over MC-LAG interfaces is used, then the 185 destination IP address MUST be set to the loopback address 186 127.0.0.1/32 for IPv4 [RFC1812], or the loopback address ::1/128 for 187 IPv6 [RFC4291]. 189 5. IANA Considerations 191 This document makes no requests for IANA allocations. This section 192 may be deleted by RFC Editor. 194 6. Security Considerations 196 This document does not introduce new security concerns but inherits 197 all security considerations discussed in [RFC5881] and [RFC7130]. 199 7. Acknowledgements 201 TBD 203 8. References 205 8.1. Normative References 207 [IEEE.802.1AX.2008] 208 "IEEE Standard for Local and metropolitan area networks - 209 Link Aggregation", IEEE 802.1-AX, November 2008. 211 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 212 Requirement Levels", BCP 14, RFC 2119, 213 DOI 10.17487/RFC2119, March 1997, 214 . 216 [RFC5586] Bocci, M., Ed., Vigoureux, M., Ed., and S. Bryant, Ed., 217 "MPLS Generic Associated Channel", RFC 5586, 218 DOI 10.17487/RFC5586, June 2009, 219 . 221 [RFC5881] Katz, D. and D. Ward, "Bidirectional Forwarding Detection 222 (BFD) for IPv4 and IPv6 (Single Hop)", RFC 5881, 223 DOI 10.17487/RFC5881, June 2010, 224 . 226 [RFC7130] Bhatia, M., Ed., Chen, M., Ed., Boutros, S., Ed., 227 Binderberger, M., Ed., and J. Haas, Ed., "Bidirectional 228 Forwarding Detection (BFD) on Link Aggregation Group (LAG) 229 Interfaces", RFC 7130, DOI 10.17487/RFC7130, February 230 2014, . 232 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 233 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 234 May 2017, . 236 8.2. Informative 238 [RFC1812] Baker, F., Ed., "Requirements for IP Version 4 Routers", 239 RFC 1812, DOI 10.17487/RFC1812, June 1995, 240 . 242 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 243 Architecture", RFC 4291, DOI 10.17487/RFC4291, February 244 2006, . 246 Authors' Addresses 248 Greg Mirsky 249 ZTE Corp. 251 Email: gregimirsky@gmail.com 253 Jeff Tantsura 254 Apstra 256 Email: jefftant.ietf@gmail.com 258 Gyan Mishra 259 Verizon Inc. 261 Email: gyan.s.mishra@verizon.com