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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: May 20, 2021 H. Smit 7 Independent 8 November 16, 2020 10 TLV support for BMP Route Monitoring and Peer Down Messages 11 draft-ietf-grow-bmp-tlv-04 13 Abstract 15 Most of the message types defined by the BGP Monitoring Protocol 16 (BMP) do provision for optional trailing data. However, Route 17 Monitoring messages (to provide a snapshot of the monitored Routing 18 Information Base) and Peer Down messages (to indicate that a peering 19 session was terminated) do not. Supporting optional data in TLV 20 format across all BMP message types allows for an homogeneous and 21 extensible surface that would be useful for the most different use- 22 cases that need to convey additional data to a BMP station. While it 23 is not intended for this document to cover any specific utilization 24 scenario, it defines a simple way to support optional TLV data in all 25 message types. 27 Status of This Memo 29 This Internet-Draft is submitted in full conformance with the 30 provisions of BCP 78 and BCP 79. 32 Internet-Drafts are working documents of the Internet Engineering 33 Task Force (IETF). Note that other groups may also distribute 34 working documents as Internet-Drafts. The list of current Internet- 35 Drafts is at https://datatracker.ietf.org/drafts/current/. 37 Internet-Drafts are draft documents valid for a maximum of six months 38 and may be updated, replaced, or obsoleted by other documents at any 39 time. It is inappropriate to use Internet-Drafts as reference 40 material or to cite them other than as "work in progress." 42 This Internet-Draft will expire on May 20, 2021. 44 Copyright Notice 46 Copyright (c) 2020 IETF Trust and the persons identified as the 47 document authors. All rights reserved. 49 This document is subject to BCP 78 and the IETF Trust's Legal 50 Provisions Relating to IETF Documents 51 (https://trustee.ietf.org/license-info) in effect on the date of 52 publication of this document. Please review these documents 53 carefully, as they describe your rights and restrictions with respect 54 to this document. Code Components extracted from this document must 55 include Simplified BSD License text as described in Section 4.e of 56 the Trust Legal Provisions and are provided without warranty as 57 described in the Simplified BSD License. 59 Table of Contents 61 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 62 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 63 3. TLV encoding . . . . . . . . . . . . . . . . . . . . . . . . 3 64 4. BMP Message Format . . . . . . . . . . . . . . . . . . . . . 4 65 4.1. Common Header . . . . . . . . . . . . . . . . . . . . . . 4 66 4.2. TLV data in Route Monitoring . . . . . . . . . . . . . . 4 67 4.3. TLV data in Peer Down . . . . . . . . . . . . . . . . . . 5 68 4.4. TLV data in other BMP messages . . . . . . . . . . . . . 5 69 5. Security Considerations . . . . . . . . . . . . . . . . . . . 5 70 6. Operational Considerations . . . . . . . . . . . . . . . . . 5 71 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 72 8. Normative References . . . . . . . . . . . . . . . . . . . . 6 73 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 6 74 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 76 1. Introduction 78 The BGP Monitoring Protocol (BMP) is defined in RFC 7854 [RFC7854]. 80 The Route Monitoring message consists of: 82 o Common Header 84 o Per-Peer Header 86 o BGP Update PDU 88 The Peer Down Notification message consists of: 90 o Common Header 92 o Per-Peer Header 94 o Reason 96 o Data (only if Reason code is 1, 2 or 3) 97 This means that both Route Monitoring and Peer Down messages have a 98 non-extensible format. In the Route Monitoring case, this is 99 limiting if wanting to transmit characteristics of transported NLRIs 100 (ie. to help stateless parsing) or to add vendor-specific data. In 101 the Peer Down case, this is limiting if matching TLVs sent with the 102 Peer Up is desired. The proposal of this document is to bump the BMP 103 version, for backward compatibility, and allow all message types to 104 provision for trailing TLV data. 106 2. Terminology 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 RFC 2119 [RFC2119] RFC 8174 [RFC8174] when, and only when, they 112 appear in all capitals, as shown here. 114 3. TLV encoding 116 The TLV data type is already defined in Section 4.4 of [RFC7854] for 117 the Initiation and Peer Up message types. A TLV consists of: 119 o 2 octets of TLV Type, 121 o 2 octets of TLV Length, 123 o 0 or more octets of TLV Value. 125 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 1 126 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 127 | Type (2 octets) | Length (2 octets) | 128 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 129 ~ Value (variable) ~ 130 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 132 Figure 1 134 TLVs SHOULD be sorted by their code point. Multiple TLVs of the same 135 type can be repeated as part of the same message, and it is left to 136 the specific use-cases whether all, any, the first or the last TLV 137 should be considered. 139 In Route Monitoring messages there may be a need to map TLVs to NLRIs 140 contained in the BGP Update message, for example, to express 141 additional characteristics of a specific NLRI. For this purpose 142 specifically TLVs in Route Monitoring messages can be optionally 143 indexed, with the index starting at zero to refer to the first NLRI, 144 and 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 4. BMP Message Format 159 4.1. Common Header 161 Section 4.1 of [RFC7854] defines the Common Header. While the 162 structure remains unaltered, the following two definitions are 163 changed: 165 o Version: Indicates the BMP version. This is set to '4' for all 166 messages. 168 o Message Length: Total length of the message in bytes (including 169 headers, encapsulated BGP message and optional data) 171 4.2. TLV data in Route Monitoring 173 The Route Monitoring message type is defined in Section 4.6 of 174 [RFC7854]. The BGP Update PDU Section 4.3 of [RFC4271] MAY be 175 followed by TLV data. This document defines the following new code 176 points to help stateless parsing of BGP Update PDUs: 178 o Type = TBD1: the BGP Update PDU is encoded with support for the 179 4-octet AS number capability RFC 6793 [RFC6793], value MUST be 180 boolean. 182 o Type = TBD2: the BGP Update PDU is encoded with the ADD-PATH 183 capability RFC 7911 [RFC7911], value MUST be boolean. 185 o Type = TBD3: the BGP Update PDU is encoded with the Multiple 186 Labels capability RFC 8277 [RFC8277], value MUST be boolean. 188 4.3. TLV data in Peer Down 190 The Peer Down Notification message type is defined in Section 4.9 of 191 [RFC7854]. For Reason codes 1 or 3, a BGP Notification PDU follows; 192 the PDU MAY be followed by TLV data. For Reason code 2, a 2-byte 193 field to give additional FSM info follows; this field MAY be followed 194 by TLV data. For all other Reason codes, TLV data MAY follow the 195 Reason field. 197 4.4. TLV data in other BMP messages 199 All other message types defined in RFC7854 [RFC7854] do already 200 provision for TLV data. It is RECOMMENDED that all future BMP 201 message types will provision for trailing TLV data. 203 5. Security Considerations 205 It is not believed that this document adds any additional security 206 considerations. 208 6. Operational Considerations 210 In Route Monitoring messages, the number of TLVs can be bound to the 211 amount of NLRIs carried in the BGP Update message. This may degrade 212 the packing of information in such messages and have specific impacts 213 on the memory and CPU used in a BMP implementation. As a result of 214 that it should always be possible to disable such features to 215 mitigate their impact. 217 7. IANA Considerations 219 This document defines the following new TLV types for BMP Route 220 Monitoring and Peer Down messages (Section 4.2): 222 o Type = TBD1: Support for the 4-octet AS number capability. The 223 value field contains a boolean value of 1 if the BGP Update PDU 224 enclosed in the Route Monitoring message was encoded according to 225 the capability. 227 o Type = TBD2: ADD-PATH capability. The value field contains a 228 boolean value of 1 if the BGP Update PDU enclosed in the Route 229 Monitoring message was encoded according to the capability. 231 o Type = TBD3: Multiple Labels capability. The value field contains 232 a boolean value of 1 if the BGP Update PDU enclosed in the Route 233 Monitoring message was encoded according to the capability. 235 8. Normative References 237 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 238 Requirement Levels", BCP 14, RFC 2119, 239 DOI 10.17487/RFC2119, March 1997, 240 . 242 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 243 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 244 DOI 10.17487/RFC4271, January 2006, 245 . 247 [RFC6793] Vohra, Q. and E. Chen, "BGP Support for Four-Octet 248 Autonomous System (AS) Number Space", RFC 6793, 249 DOI 10.17487/RFC6793, December 2012, 250 . 252 [RFC7854] Scudder, J., Ed., Fernando, R., and S. Stuart, "BGP 253 Monitoring Protocol (BMP)", RFC 7854, 254 DOI 10.17487/RFC7854, June 2016, 255 . 257 [RFC7911] Walton, D., Retana, A., Chen, E., and J. Scudder, 258 "Advertisement of Multiple Paths in BGP", RFC 7911, 259 DOI 10.17487/RFC7911, July 2016, 260 . 262 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 263 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 264 May 2017, . 266 [RFC8277] Rosen, E., "Using BGP to Bind MPLS Labels to Address 267 Prefixes", RFC 8277, DOI 10.17487/RFC8277, October 2017, 268 . 270 Acknowledgements 272 The authors would like to thank Jeff Haas and Camilo Cardona for 273 their valuable input. The authors would also like to thank Greg 274 Skinner for his review. 276 Authors' Addresses 277 Paolo Lucente 278 NTT 279 Siriusdreef 70-72 280 Hoofddorp, WT 2132 281 NL 283 Email: paolo@ntt.net 285 Yunan Gu 286 Huawei 287 Huawei Bld., No.156 Beiqing Rd. 288 Beijing 100095 289 China 291 Email: guyunan@huawei.com 293 Henk Smit 294 Independent 295 NL 297 Email: hhw.smit@xs4all.nl