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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 (November 18, 2020) is 1248 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 22, 2021 Apstra 6 G. Mishra 7 Verizon Inc. 8 November 18, 2020 10 Bidirectional Forwarding Detection (BFD) on Multi-chassis Link 11 Aggregation Group (MC-LAG) Interfaces 12 draft-mtm-rtgwg-bfd-mc-lag-01 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 22, 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 . . . . . . . . . . . . 3 63 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 64 6. Security Considerations . . . . . . . . . . . . . . . . . . . 4 65 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 66 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 67 8.1. Normative References . . . . . . . . . . . . . . . . . . 4 68 8.2. Informative . . . . . . . . . . . . . . . . . . . . . . . 5 69 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 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 BFD: Bidirectional Forwarding Detection 91 LAG: Link Aggregation Group 93 LACP: Link Aggregation Control Protocol 95 MC-LAG: Multi-chassis Link Aggregation Group 96 MPLS: Multi-Protocol Label Switching 98 1.1.2. Requirements Language 100 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 101 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 102 "OPTIONAL" in this document are to be interpreted as described in BCP 103 14 [RFC2119] [RFC8174] when, and only when, they appear in all 104 capitals, as shown here. 106 2. Problem Statement 108 [RFC7130] does not specify the selection of the destination IP 109 address for the BFD control packet. The only requirement related to 110 the selection is in Section 2.1, stating that the use of the address 111 family across all member links of the given LAG MUST be consistent 112 across all the links. Thus it is implied that the same unicast IP 113 address will be used on all member links of the LAG as the use of 114 different destination addresses would defeat the purpose of [RFC7130] 115 transforming the case into a set of single-hop BFD sessions 116 [RFC5881]. But a single unicast IP address may not work in the MC- 117 LAG case as the member links are terminated on the separate chassis. 118 This document proposes overcoming this problem if using IP or Multi- 119 Protocol Label Switching (MPLS) data plane encapsulation. 121 3. BFD on MC-LAG with IP-only Data Plane 123 As described in [RFC7130], a micro-BFD session on the LAG interfaces 124 may use IPv4 or IPv6 address family. In some cases, two sessions, 125 one with IPv4 and one with IPv6 addresses, may run concurrently. 126 This document doesn't change any of these but specifies the selection 127 of the destination IP address in the MC-LAG use case: 129 o if IPv4 address family is used for the micro-BFD session, then an 130 address from the link-local multicast address 224.0.0.0/24 range 131 SHOULD be used as the destination IP address. The subnet 132 broadcast address MAY be used as the destination IP address as 133 well; 135 o if the address family used is IPv6, then the IPv6 All Routers 136 address with the link scope, as defined in [RFC4291], FF02::2/128 137 MUST be used as the destination IP address. 139 4. BFD on MC-LAG with IP/MPLS Data Plane 141 IP/UDP is the most natural encapsulation format for the case of 142 micro-BFD on MC-LAG over IP/MPLS data plane as displayed in Figure 1. 144 0 1 2 3 145 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 1 146 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 147 ~ MPLS Label Stack ~ 148 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+------- 149 ~ ~ | 150 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ IP 151 | Destination IP address | 152 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Header 153 | Source IP address | | 154 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+------ 155 | UDP header | 156 | | 157 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 158 ~ BFD Control Packet ~ 159 | | 160 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 162 Figure 1: BFD on MC-LAG member link on IPv4/MPLS data plane 164 An IP and UDP headers immediately follow an MPLS label stack. The 165 destination IP address MUST be set to the loopback address 166 127.0.0.1/32 for IPv4 [RFC1812], or the loopback address ::1/128 for 167 IPv6 [RFC4291]. TTL or Hop Limit field value MUST be set to 255, 168 according to [RFC5881]. 170 5. IANA Considerations 172 This document makes no requests for IANA allocations. This section 173 may be deleted by RFC Editor. 175 6. Security Considerations 177 This document does not introduce new security concerns but inherits 178 all security considerations discussed in [RFC5881] and [RFC7130]. 180 7. Acknowledgements 182 TBD 184 8. References 186 8.1. Normative References 188 [IEEE.802.1AX.2008] 189 "IEEE Standard for Local and metropolitan area networks - 190 Link Aggregation", IEEE 802.1-AX, November 2008. 192 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 193 Requirement Levels", BCP 14, RFC 2119, 194 DOI 10.17487/RFC2119, March 1997, 195 . 197 [RFC5881] Katz, D. and D. Ward, "Bidirectional Forwarding Detection 198 (BFD) for IPv4 and IPv6 (Single Hop)", RFC 5881, 199 DOI 10.17487/RFC5881, June 2010, 200 . 202 [RFC7130] Bhatia, M., Ed., Chen, M., Ed., Boutros, S., Ed., 203 Binderberger, M., Ed., and J. Haas, Ed., "Bidirectional 204 Forwarding Detection (BFD) on Link Aggregation Group (LAG) 205 Interfaces", RFC 7130, DOI 10.17487/RFC7130, February 206 2014, . 208 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 209 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 210 May 2017, . 212 8.2. Informative 214 [RFC1812] Baker, F., Ed., "Requirements for IP Version 4 Routers", 215 RFC 1812, DOI 10.17487/RFC1812, June 1995, 216 . 218 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 219 Architecture", RFC 4291, DOI 10.17487/RFC4291, February 220 2006, . 222 Authors' Addresses 224 Greg Mirsky 225 ZTE Corp. 227 Email: gregimirsky@gmail.com 229 Jeff Tantsura 230 Apstra 232 Email: jefftant.ietf@gmail.com 234 Gyan Mishra 235 Verizon Inc. 237 Email: gyan.s.mishra@verizon.com