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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Global Routing Operations P. Lucente 3 Internet-Draft NTT 4 Updates: 7854 (if approved) Y. Gu 5 Intended status: Standards Track Huawei 6 Expires: April 28, 2022 October 25, 2021 8 TLV support for BMP Route Monitoring and Peer Down Messages 9 draft-ietf-grow-bmp-tlv-06 11 Abstract 13 Most of the message types defined by the BGP Monitoring Protocol 14 (BMP) do provision for optional trailing data. However, Route 15 Monitoring messages (to provide a snapshot of the monitored Routing 16 Information Base) and Peer Down messages (to indicate that a peering 17 session was terminated) do not. Supporting optional data in TLV 18 format across all BMP message types allows for an homogeneous and 19 extensible surface that would be useful for the most different use- 20 cases that need to convey additional data to a BMP station. While it 21 is not intended for this document to cover any specific utilization 22 scenario, it defines a simple way to support optional TLV data in all 23 message types. 25 Status of This Memo 27 This Internet-Draft is submitted in full conformance with the 28 provisions of BCP 78 and BCP 79. 30 Internet-Drafts are working documents of the Internet Engineering 31 Task Force (IETF). Note that other groups may also distribute 32 working documents as Internet-Drafts. The list of current Internet- 33 Drafts is at https://datatracker.ietf.org/drafts/current/. 35 Internet-Drafts are draft documents valid for a maximum of six months 36 and may be updated, replaced, or obsoleted by other documents at any 37 time. It is inappropriate to use Internet-Drafts as reference 38 material or to cite them other than as "work in progress." 40 This Internet-Draft will expire on April 28, 2022. 42 Copyright Notice 44 Copyright (c) 2021 IETF Trust and the persons identified as the 45 document authors. All rights reserved. 47 This document is subject to BCP 78 and the IETF Trust's Legal 48 Provisions Relating to IETF Documents 49 (https://trustee.ietf.org/license-info) in effect on the date of 50 publication of this document. Please review these documents 51 carefully, as they describe your rights and restrictions with respect 52 to this document. Code Components extracted from this document must 53 include Simplified BSD License text as described in Section 4.e of 54 the Trust Legal Provisions and are provided without warranty as 55 described in the Simplified BSD License. 57 Table of Contents 59 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 60 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 61 3. TLV encoding . . . . . . . . . . . . . . . . . . . . . . . . 3 62 4. BMP Message Format . . . . . . . . . . . . . . . . . . . . . 4 63 4.1. Common Header . . . . . . . . . . . . . . . . . . . . . . 4 64 4.2. TLV data in Route Monitoring . . . . . . . . . . . . . . 4 65 4.3. TLV data in Peer Down . . . . . . . . . . . . . . . . . . 5 66 4.4. TLV data in other BMP messages . . . . . . . . . . . . . 5 67 5. Security Considerations . . . . . . . . . . . . . . . . . . . 5 68 6. Operational Considerations . . . . . . . . . . . . . . . . . 5 69 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 70 8. Normative References . . . . . . . . . . . . . . . . . . . . 6 71 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 6 72 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 74 1. Introduction 76 The BGP Monitoring Protocol (BMP) is defined in RFC 7854 [RFC7854]. 78 The Route Monitoring message consists of: 80 o Common Header 82 o Per-Peer Header 84 o BGP Update PDU 86 The Peer Down Notification message consists of: 88 o Common Header 90 o Per-Peer Header 92 o Reason 94 o Data (only if Reason code is 1, 2 or 3) 95 This means that both Route Monitoring and Peer Down messages have a 96 non-extensible format. In the Route Monitoring case, this is 97 limiting if wanting to transmit characteristics of transported NLRIs 98 (ie. to help stateless parsing) or to add vendor-specific data. In 99 the Peer Down case, this is limiting if matching TLVs sent with the 100 Peer Up is desired. The proposal of this document is to bump the BMP 101 version, for backward compatibility, and allow all message types to 102 provision for trailing TLV data. 104 2. Terminology 106 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 107 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 108 "OPTIONAL" in this document are to be interpreted as described in BCP 109 14 RFC 2119 [RFC2119] RFC 8174 [RFC8174] when, and only when, they 110 appear in all capitals, as shown here. 112 3. TLV encoding 114 The TLV data type is already defined in Section 4.4 of [RFC7854] for 115 the Initiation and Peer Up message types. A TLV consists of: 117 o 2 octets of TLV Type, 119 o 2 octets of TLV Length, 121 o 0 or more octets of TLV Value. 123 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 1 124 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 125 | Type (2 octets) | Length (2 octets) | 126 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 127 ~ Value (variable) ~ 128 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 130 Figure 1 132 TLVs SHOULD be sorted by their code point. Multiple TLVs of the same 133 type can be repeated as part of the same message, and it is left to 134 the specific use-cases whether all, any, the first or the last TLV 135 should be considered. 137 Route Monitoring messages may require per-NLRI TLVs, that is, there 138 may be a need to map TLVs to NLRIs contained in the BGP Update 139 message, for example, to express additional characteristics of a 140 specific NLRI. For this purpose specifically, TLVs in Route 141 Monitoring messages MUST be indexed, with the index starting at one 142 (1) to refer to the first NLRI. Index zero (0) specifies that a TLV 143 does apply to all NLRIs contained in the BGP Update message. Indexed 144 TLVs are encoded as in the following figure: 146 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 1 147 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 148 | Type (2 octets) | Length (2 octets) | 149 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 150 | Index (2 octets) | 151 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 152 ~ Value (variable) ~ 153 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 155 Figure 2 157 Of the BMP message types defined so far, indexed TLVs do apply only 158 to Route Monitoring messages and, for example, they do not apply to 159 Route Mirroring ones because the sender may not be aware of the 160 payload of the transported BGP Update message. 162 4. BMP Message Format 164 4.1. Common Header 166 Section 4.1 of [RFC7854] defines the Common Header. While the 167 structure remains unaltered, the following two definitions are 168 changed: 170 o Version: Indicates the BMP version. This is set to '4' for all 171 messages. 173 o Message Length: Total length of the message in bytes (including 174 headers, encapsulated BGP message and optional data) 176 4.2. TLV data in Route Monitoring 178 The Route Monitoring message type is defined in Section 4.6 of 179 [RFC7854]. The BGP Update PDU Section 4.3 of [RFC4271] MAY be 180 followed by TLV data. This document defines the following new code 181 points to help stateless parsing of BGP Update PDUs: 183 o Type = TBD1: the BGP Update PDU is encoded with support for the 184 4-octet AS number capability RFC 6793 [RFC6793], value MUST be 185 boolean. 187 o Type = TBD2: the BGP Update PDU is encoded with the ADD-PATH 188 capability RFC 7911 [RFC7911], value MUST be boolean. 190 o Type = TBD3: the BGP Update PDU is encoded with the Multiple 191 Labels capability RFC 8277 [RFC8277], value MUST be boolean. 193 4.3. TLV data in Peer Down 195 The Peer Down Notification message type is defined in Section 4.9 of 196 [RFC7854]. For Reason codes 1 or 3, a BGP Notification PDU follows; 197 the PDU MAY be followed by TLV data. For Reason code 2, a 2-byte 198 field to give additional FSM info follows; this field MAY be followed 199 by TLV data. For all other Reason codes, TLV data MAY follow the 200 Reason field. 202 4.4. TLV data in other BMP messages 204 All other message types defined in RFC7854 [RFC7854] do already 205 provision for TLV data. It is RECOMMENDED that all future BMP 206 message types will provision for trailing TLV data. 208 5. Security Considerations 210 It is not believed that this document adds any additional security 211 considerations. 213 6. Operational Considerations 215 In Route Monitoring messages, the number of TLVs can be bound to the 216 amount of NLRIs carried in the BGP Update message. This may degrade 217 the packing of information in such messages and have specific impacts 218 on the memory and CPU used in a BMP implementation. As a result of 219 that it should always be possible to disable such features to 220 mitigate their impact. 222 7. IANA Considerations 224 This document defines the following new TLV types for BMP Route 225 Monitoring and Peer Down messages (Section 4.2): 227 o Type = TBD1: Support for the 4-octet AS number capability. The 228 value field contains a boolean value of 1 if the BGP Update PDU 229 enclosed in the Route Monitoring message was encoded according to 230 the capability. 232 o Type = TBD2: ADD-PATH capability. The value field contains a 233 boolean value of 1 if the BGP Update PDU enclosed in the Route 234 Monitoring message was encoded according to the capability. 236 o Type = TBD3: Multiple Labels capability. The value field contains 237 a boolean value of 1 if the BGP Update PDU enclosed in the Route 238 Monitoring message was encoded according to the capability. 240 8. Normative References 242 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 243 Requirement Levels", BCP 14, RFC 2119, 244 DOI 10.17487/RFC2119, March 1997, 245 . 247 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 248 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 249 DOI 10.17487/RFC4271, January 2006, 250 . 252 [RFC6793] Vohra, Q. and E. Chen, "BGP Support for Four-Octet 253 Autonomous System (AS) Number Space", RFC 6793, 254 DOI 10.17487/RFC6793, December 2012, 255 . 257 [RFC7854] Scudder, J., Ed., Fernando, R., and S. Stuart, "BGP 258 Monitoring Protocol (BMP)", RFC 7854, 259 DOI 10.17487/RFC7854, June 2016, 260 . 262 [RFC7911] Walton, D., Retana, A., Chen, E., and J. Scudder, 263 "Advertisement of Multiple Paths in BGP", RFC 7911, 264 DOI 10.17487/RFC7911, July 2016, 265 . 267 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 268 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 269 May 2017, . 271 [RFC8277] Rosen, E., "Using BGP to Bind MPLS Labels to Address 272 Prefixes", RFC 8277, DOI 10.17487/RFC8277, October 2017, 273 . 275 Acknowledgements 277 The authors would like to thank Jeff Haas, Camilo Cardona, Thomas 278 Graf and Pierre Francois for their valuable input. The authors would 279 also like to thank Greg Skinner for his review. 281 Authors' Addresses 283 Paolo Lucente 284 NTT 285 Siriusdreef 70-72 286 Hoofddorp, WT 2132 287 NL 289 Email: paolo@ntt.net 291 Yunan Gu 292 Huawei 293 Huawei Bld., No.156 Beiqing Rd. 294 Beijing 100095 295 China 297 Email: guyunan@huawei.com