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'I-D.ietf-idr-best-external' == Outdated reference: A later version (-20) exists of draft-ietf-rtgwg-bgp-pic-17 ** Downref: Normative reference to an Informational draft: draft-ietf-rtgwg-bgp-pic (ref. 'I-D.ietf-rtgwg-bgp-pic') == Outdated reference: A later version (-12) exists of draft-lapukhov-bgp-ecmp-considerations-07 ** Downref: Normative reference to an Informational draft: draft-lapukhov-bgp-ecmp-considerations (ref. 'I-D.lapukhov-bgp-ecmp-considerations') == Outdated reference: A later version (-02) exists of draft-lucente-grow-bmp-tlv-ebit-01 Summary: 3 errors (**), 0 flaws (~~), 40 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group C. Cardona 3 Internet-Draft P. Lucente 4 Intended status: Standards Track NTT 5 Expires: 12 May 2022 P. Francois 6 INSA-Lyon 7 Y. Gu 8 Huawei 9 T. Graf 10 Swisscom 11 8 November 2021 13 BMP Extension for Path Status TLV 14 draft-cppy-grow-bmp-path-marking-tlv-09 16 Abstract 18 The BGP Monitoring Protocol (BMP) provides an interface for obtaining 19 BGP Path information. BGP Path Information is conveyed within BMP 20 Route Monitoring (RM) messages. This document proposes an extension 21 to BMP to convey the status of a BGP path before and after being 22 processed by the BGP best-path selection algorithm. This extension 23 makes use of the TLV mechanims described in draft-ietf-grow-bmp-tlv 24 [I-D.ietf-grow-bmp-tlv] and draft-lucente-grow-bmp-tlv-ebit 25 [I-D.lucente-grow-bmp-tlv-ebit]. 27 Requirements Language 29 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 30 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 31 "OPTIONAL" in this document are to be interpreted as described in BCP 32 14 RFC 2119 [RFC2119] RFC 8174 [RFC8174] when, and only when, they 33 appear in all capitals, as shown here. 35 Status of This Memo 37 This Internet-Draft is submitted in full conformance with the 38 provisions of BCP 78 and BCP 79. 40 Internet-Drafts are working documents of the Internet Engineering 41 Task Force (IETF). Note that other groups may also distribute 42 working documents as Internet-Drafts. The list of current Internet- 43 Drafts is at https://datatracker.ietf.org/drafts/current/. 45 Internet-Drafts are draft documents valid for a maximum of six months 46 and may be updated, replaced, or obsoleted by other documents at any 47 time. It is inappropriate to use Internet-Drafts as reference 48 material or to cite them other than as "work in progress." 49 This Internet-Draft will expire on 12 May 2022. 51 Copyright Notice 53 Copyright (c) 2021 IETF Trust and the persons identified as the 54 document authors. All rights reserved. 56 This document is subject to BCP 78 and the IETF Trust's Legal 57 Provisions Relating to IETF Documents (https://trustee.ietf.org/ 58 license-info) in effect on the date of publication of this document. 59 Please review these documents carefully, as they describe your rights 60 and restrictions with respect to this document. Code Components 61 extracted from this document must include Simplified BSD License text 62 as described in Section 4.e of the Trust Legal Provisions and are 63 provided without warranty as described in the Simplified BSD License. 65 Table of Contents 67 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 68 2. Path Status TLV . . . . . . . . . . . . . . . . . . . . . . . 3 69 2.1. IANA-registered Path Status TLV . . . . . . . . . . . . . 3 70 2.2. Enterprise-specific Path Status TLV . . . . . . . . . . . 5 71 3. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6 72 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 73 5. Security Considerations . . . . . . . . . . . . . . . . . . . 7 74 6. Normative References . . . . . . . . . . . . . . . . . . . . 7 75 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 77 1. Introduction 79 For a given prefix, multiple paths with different path status, e.g., 80 the "best-path", "back-up path" and so on, may co-exist in the BGP 81 RIB after being processed by the local policy and the BGP decision 82 process. The path status information is currently not carried in the 83 BGP Update Message RFC4271 [RFC4271] or in the BMP Update Message 84 RFC7854 [RFC7854]. 86 External systems can use the path status for various applications. 87 The path status is commonly checked by operators when performing 88 troubleshooting. Having such status stored in a centralized system 89 can enable the development of tools that facilitate this process. 90 Optimisation systems can include the path status in their process, 91 and also use the status as a validation source (since it can compare 92 the calculated state to the actual outcome of the network, such as 93 primary and backup path). As a final example, path status 94 information can complement other centralized sources of data, for 95 example, flow collectors. 97 This document defines a so-called Path Status TLV to convey the BGP 98 path status to the BMP server. The BMP Path Status TLV is carried in 99 the BMP Route Monitoring (RM) Message. 101 2. Path Status TLV 103 This document defines two types of Path Status TLVs: one is the IANA- 104 registered Path Status TLV, and the other is the Enterprise-specific 105 Path Status TLV. 107 2.1. IANA-registered Path Status TLV 109 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 1 110 +-------------------------------+-------------------------------+ 111 |E| Type (15 bits) | Length (2 octets) | 112 +---------------------------------------------------------------+ 113 | Index (2 octets) | 114 +-------------------------------+-------------------------------+ 115 | Path Status (4 octets) | 116 +---------------------------------------------------------------+ 117 | Reason Code (2 octets, optional) | 118 +---------------------------------------------------------------+ 120 Figure 2: Encoding of IANA-Registered Path Status TLV 122 * E bit: For an IANA-registered TLV, the E bit MUST be set to 0. 124 * Type = TBD2 (15 Bits): indicates that it is the IANA-registered 125 Path Status TLV. 127 * Length (2 Octets): indicates the length of the value field of the 128 Path Status TLV. The value field further consists of the Path- 129 Status field and Reason Code field. 131 * Index (2 Octets): indicates the prefix that this TLV is 132 describing. The index is the encapsulation order, starting from 133 0, of the prefix in the BGP Update PDU. 135 * Path Status (4 Octets): indicates the path status of the BGP 136 Update PDU encapsulated in the RM Message. Currently 8 types of 137 path status are defined, as shown in Table 1. All zeros are 138 reserved. 140 * Reason Code (2 Octets, optional): indicates the reason of the path 141 status indicated in the Path Status field. The reason code field 142 is optional. If no reason code is carried, this field is empty. 143 If a reason code is carried, the reason code is indicated by a 144 2-byte value, which is defined in Table 2. 146 +------------+------------------+ 147 | Value | Path type | 148 +-------------------------------+ 149 | 0x00000001 | Invalid | 150 | 0x00000002 | Best | 151 | 0x00000004 | Non-selected | 152 | 0x00000008 | Primary | 153 | 0x00000010 | Backup | 154 | 0x00000020 | Non-installed | 155 | 0x00000040 | Best-external | 156 | 0x00000080 | Add-Path | 157 +------------+------------------+ 159 Table 1: IANA-Registered Path Type 161 The Path Status field contains a bitmap where each bit encodes a 162 specific role of the path. Multiple bits may be set when multiple 163 path status apply to a path. 165 * The best-path is defined in RFC4271 [RFC4271] and the best- 166 external path is defined in draft-ietf-idr-best-external 167 [I-D.ietf-idr-best-external]. 169 * An invalid path is a route that does not enter the BGP decision 170 process. 172 * A non-selected path is a route that is not selected in the BGP 173 decision process. Back-up routes are considered non-selected, 174 while the best and ECMP routes are not considered as non-selected. 176 * A primary path is a recursive or non-recursive path whose nexthop 177 resolution ends with an adjacency draft-ietf-rtgwg-bgp-pic 178 [I-D.ietf-rtgwg-bgp-pic]. A prefix can have more than one primary 179 path if multipath is configured 180 draft-lapukhov-bgp-ecmp-considerations 181 [I-D.lapukhov-bgp-ecmp-considerations]. A best-path is also 182 considered as a primary path. 184 * A backup path is also installed in the RIB, but it is not used 185 until some or all primary paths become unreachable. Backup paths 186 are used for fast convergence in the event of failures. 188 * A non-installed path refers to the route that is not installed 189 into the IP routing table. 191 * For the advertisement of multiple paths for the same address 192 prefix without the new paths implicitly replacing any previous 193 ones, the add-path status is applied RFC7911 [RFC7911]. 195 The path status TLV does not force a BMP client to send any of these 196 paths. It just provides a method to mark the paths that are 197 available with their status. 199 +----------+-----------------------------------------------------+ 200 | Value | Reason code | 201 +----------------------------------------------------------------+ 202 | [0x0001] | invalid for super network | 203 | [0x0002] | invalid for dampening | 204 | [0x0003] | invalid for damping history | 205 | [0x0004] | invalid for policy deny | 206 | [0x0005] | invalid for ROV not valid | 207 | [0x0006] | invalid for interface error | 208 | [0x0007] | invalid for nexthop route unreachable | 209 | [0x0008] | invalid for nexthop tunnel unreachable | 210 | [0x0009] | invalid for nexthop restrain | 211 | [0x000A] | invalid for not supporting BGP LSP relay | 212 | [0x000B] | invalid for being inactive within VPN insance | 213 | [0x000C] | invalid for prefix sid not exist | 214 | [0x000D] | not preferred for peer address | 215 | [0x000E] | not preferred for router ID | 216 | [0x000F] | not preferred for Cluster List | 217 | [0x0010] | not preferred for IGP cost | 218 | [0x0011] | not preferred for peer type | 219 | [0x0012] | not preferred for MED | 220 | [0x0013] | not preferred for origin | 221 | [0x0014] | not preferred for AS Path | 222 | [0x0015] | not preferred for route type | 223 | [0x0016] | not preferred for Local preference | 224 | [0x0017] | not preferred for Weight | 225 | [0x0018] | not preferred for path to next hop with bit error | 226 | [0x0019] | not preferred for path id | 227 | [0x001A] | not preferred for ROV validation | 228 | [0x001B] | not preferred for originate IP | 229 | [0x001C] | not preferred for route distinguisher | 230 | [0x001D] | not preferred for delayed route selection | 231 | [0x001E] | not preferred for imported from other instances | 232 | [0x001F] | not preferred for med plus igp cost | 233 | [0x0020] | not preferred for AIGP | 234 | [0x0021] | not preferred for BGP LSP aigp for next hop relay | 235 | [0x0022] | not preferred for nexthop IP | 236 +----------+-----------------------------------------------------+ 238 Table 2: IANA-Registered Reason Code 240 2.2. Enterprise-specific Path Status TLV 241 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 1 242 +-------------------------------+-------------------------------+ 243 |E| Type (15 bits) | Length (2 octets) | 244 +-------------------------------+-------------------------------+ 245 | PEN number (4 octets) | 246 +---------------------------------------------------------------+ 247 | Index (2 octets) | 248 +---------------------------------------------------------------+ 249 | Path Status (4 octets) | 250 +---------------------------------------------------------------+ 251 | Reason Code (2 octets, optional) | 252 +---------------------------------------------------------------+ 254 Figure 3: Encoding of Enterprise-specific Path Status TLV 256 * E bit: For an Enterprise-specific TLV, the E bit MUST be set to 1. 258 * Type = 1 (15 Bits): indicates that it's the Enterprise-specific 259 Path Status TLV. 261 * Length (2 Octets): indicates the length of the value field of the 262 Path Status TLV. The value field further consists of the Path- 263 Status field and Reason Code field. 265 * Index (2 Octets): indicates the prefix that this TLV is 266 describing. The index is the encapsulation order, starting from 267 0, of the prefix in the BGP Update PDU. 269 * PEN Number (4 octets): indicates the IANA enterprise number IANA- 270 PEN. 272 * Path Status (4 Octets): indicates the enterprise-specific path 273 status. The format is to be determined w.r.t. each PEN number. 275 * Reason Code (2 octets, optional): indicates the reasons/ 276 explanations of the path status indicated in the Path Status 277 field. The format is to be determined w.r.t. each PEN number. 279 3. Acknowledgments 281 We would like to thank Jeff Haas for his valuable comments. 283 4. IANA Considerations 285 This document requests that IANA assign the following new parameters 286 to the BMP parameters name space. 288 Type = TBD1 (15 Bits): indicates that it is the IANA-registered Path 289 Status TLV. 291 5. Security Considerations 293 It is not believed that this document adds any additional security 294 considerations. 296 6. Normative References 298 [I-D.ietf-grow-bmp-tlv] 299 Lucente, P. and Y. Gu, "TLV support for BMP Route 300 Monitoring and Peer Down Messages", Work in Progress, 301 Internet-Draft, draft-ietf-grow-bmp-tlv-06, 25 October 302 2021, . 305 [I-D.ietf-idr-best-external] 306 Marques, P., Fernando, R., Chen, E., Mohapatra, P., and H. 307 Gredler, "Advertisement of the best external route in 308 BGP", Work in Progress, Internet-Draft, draft-ietf-idr- 309 best-external-05, 3 January 2012, 310 . 313 [I-D.ietf-rtgwg-bgp-pic] 314 Bashandy, A., Filsfils, C., and P. Mohapatra, "BGP Prefix 315 Independent Convergence", Work in Progress, Internet- 316 Draft, draft-ietf-rtgwg-bgp-pic-17, 12 October 2021, 317 . 320 [I-D.lapukhov-bgp-ecmp-considerations] 321 Lapukhov, P. and J. Tantsura, "Equal-Cost Multipath 322 Considerations for BGP", Work in Progress, Internet-Draft, 323 draft-lapukhov-bgp-ecmp-considerations-07, 30 June 2021, 324 . 327 [I-D.lucente-grow-bmp-tlv-ebit] 328 Lucente, P. and Y. Gu, "Support for Enterprise-specific 329 TLVs in the BGP Monitoring Protocol", Work in Progress, 330 Internet-Draft, draft-lucente-grow-bmp-tlv-ebit-01, 5 May 331 2020, . 334 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 335 Requirement Levels", BCP 14, RFC 2119, 336 DOI 10.17487/RFC2119, March 1997, 337 . 339 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 340 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 341 DOI 10.17487/RFC4271, January 2006, 342 . 344 [RFC7854] Scudder, J., Ed., Fernando, R., and S. Stuart, "BGP 345 Monitoring Protocol (BMP)", RFC 7854, 346 DOI 10.17487/RFC7854, June 2016, 347 . 349 [RFC7911] Walton, D., Retana, A., Chen, E., and J. Scudder, 350 "Advertisement of Multiple Paths in BGP", RFC 7911, 351 DOI 10.17487/RFC7911, July 2016, 352 . 354 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 355 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 356 May 2017, . 358 Authors' Addresses 360 Camilo Cardona 361 NTT 362 164-168, Carrer de Numancia 363 08029 Barcelona 364 Spain 366 Email: camilo@ntt.net 368 Paolo Lucente 369 NTT 370 Siriusdreef 70-72 371 2132 Hoofddorp 372 Netherlands 374 Email: paolo@ntt.net 375 Pierre Francois 376 INSA-Lyon 377 Lyon 378 France 380 Email: Pierre.Francois@insa-lyon.fr 382 Yunan Gu 383 Huawei 384 Huawei Bld., No.156 Beiqing Rd. 385 Beijing 386 100095 387 China 389 Email: guyunan@huawei.com 391 Thomas Graf 392 Swisscom 393 Binzring 17 394 CH-8045 Zurich 395 Switzerland 397 Email: thomas.graf@swisscom.com