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'I-D.ietf-idr-best-external' == Outdated reference: A later version (-20) exists of draft-ietf-rtgwg-bgp-pic-10 ** Downref: Normative reference to an Informational draft: draft-ietf-rtgwg-bgp-pic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 'I-D.ietf-rtgwg-bgp-pic') == Outdated reference: A later version (-12) exists of draft-lapukhov-bgp-ecmp-considerations-03 ** Downref: Normative reference to an Informational draft: draft-lapukhov-bgp-ecmp-considerations (ref. 'I-D.lapukhov-bgp-ecmp-considerations') Summary: 3 errors (**), 0 flaws (~~), 4 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: July 6, 2020 P. Francois 6 INSA-Lyon 7 Y. Gu 8 Huawei 9 T. Graf 10 Swisscom 11 January 03, 2020 13 BMP Extension for Path Marking TLV 14 draft-cppy-grow-bmp-path-marking-tlv-02 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 after being processed by 22 the BGP best-path selection algorithm. This extension makes use of 23 the TLV mechanims described in draft-lucente-bmp-tlv 24 [I-D.lucente-bmp-tlv]. 26 Requirements Language 28 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 29 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 30 "OPTIONAL" in this document are to be interpreted as described in BCP 31 14 RFC 2119 [RFC2119] RFC 8174 [RFC8174] when, and only when, they 32 appear in all capitals, as shown here. 34 Status of This Memo 36 This Internet-Draft is submitted in full conformance with the 37 provisions of BCP 78 and BCP 79. 39 Internet-Drafts are working documents of the Internet Engineering 40 Task Force (IETF). Note that other groups may also distribute 41 working documents as Internet-Drafts. The list of current Internet- 42 Drafts is at https://datatracker.ietf.org/drafts/current/. 44 Internet-Drafts are draft documents valid for a maximum of six months 45 and may be updated, replaced, or obsoleted by other documents at any 46 time. It is inappropriate to use Internet-Drafts as reference 47 material or to cite them other than as "work in progress." 48 This Internet-Draft will expire on July 6, 2020. 50 Copyright Notice 52 Copyright (c) 2020 IETF Trust and the persons identified as the 53 document authors. All rights reserved. 55 This document is subject to BCP 78 and the IETF Trust's Legal 56 Provisions Relating to IETF Documents 57 (https://trustee.ietf.org/license-info) in effect on the date of 58 publication of this document. Please review these documents 59 carefully, as they describe your rights and restrictions with respect 60 to this document. Code Components extracted from this document must 61 include Simplified BSD License text as described in Section 4.e of 62 the Trust Legal Provisions and are provided without warranty as 63 described in the Simplified BSD License. 65 Table of Contents 67 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 68 2. Path Marking TLV for the RM Message . . . . . . . . . . . . . 3 69 2.1. Path Status . . . . . . . . . . . . . . . . . . . . . . . 4 70 2.1.1. IANA-registered Path Status Encoding . . . . . . . . 4 71 2.1.2. Enterprise-specific Path Status Encoding . . . . . . 5 72 2.2. Reason Code . . . . . . . . . . . . . . . . . . . . . . . 6 73 2.2.1. IANA-registered Reason Code Encoding . . . . . . . . 6 74 2.2.2. Enterprise-specific Reason Code Encoding . . . . . . 6 75 3. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7 76 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 77 4.1. Path Marking TLV . . . . . . . . . . . . . . . . . . . . 7 78 4.2. Path Marking TLV Reason Code . . . . . . . . . . . . . . 7 79 5. Security Considerations . . . . . . . . . . . . . . . . . . . 7 80 6. Normative References . . . . . . . . . . . . . . . . . . . . 7 81 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 83 1. Introduction 85 For a given prefix, multiple paths with different path status, e.g., 86 the "best-path", "back-up path" and so on, may co-exist in the BGP 87 RIB after being processed by the local policy and the BGP decision 88 process. The path status information is currently not carried in the 89 BGP Update Message RFC4271 [RFC4271] or in the BMP Update Message 90 RFC7854 [RFC7854]. 92 External systems can use the path status for various applications. 93 The path status is commonly checked by operators when performing 94 troubleshooting. Having such status stored in a centralized system 95 can enable the development of tools facilitating this process. 97 Optimisation systems can include the path status in their process, 98 and also use the status as a validation source (since it can compare 99 the calculated state to the actual outcome of the network, such as 100 primary and backup path). As a final example, path status 101 information can complement other centralized sources of data, for 102 example, flow collectors. 104 This document defines a so-called Path Marking TLV to convey the BGP 105 path status information to the BMP server. The BMP Path Marking is 106 defined to be prepended in the BMP Route Monitoring (RM) Message. 108 2. Path Marking TLV for the RM Message 110 As per RFC4271 [RFC4271], the BMP RM Message consists of the Common 111 Header, Per-Peer Header, and the BGP Update PDU. According to draft- 112 lucente-bmp-tlv [I-D.lucente-bmp-tlv] , optional trailing data in TLV 113 format is allowed in the BMP RM Message to convey characteristics of 114 transported NLRIs (i.e. to help stateless parsing) or vendor-specific 115 data. Such TLV types are to be defined for each application. 117 To include the path status along with each BGP path, we define the 118 Path Marking TLV, shown as follows. 120 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 1 121 +-------------------------------+-------------------------------+ 122 | Type (2 octets) | Length (2 octets) | 123 +-------------------------------+-------------------------------+ 124 |E| Path Status(variable) | 125 +---------------------------------------------------------------+ 126 |E| Reason Code(variable) | 127 +---------------------------------------------------------------+ 129 Figure 1: Path Marking TLV 131 o Type = TBD1 (2 Octets): indicates that it's the Path Marking TLV. 133 o Length (2 Octets): indicates the length of the value field of the 134 Path Marking TLV. The value field further consists of the Path- 135 Status field and Reason Code field. 137 o E bit (1 Bit) for Path Status: indicates if any enterprise- 138 specific path status is used after the IANA-registered path status 139 code. 141 o Path Status (4 Octets): indicates the path status of the BGP 142 Update PDU encapsulated in the RM Message. Currently 7 types of 143 path status are defined, as shown in Table 1. 145 o E bit (1 Bit) for Reason Code: indicates if any enterprise- 146 specific reason code is used after the IANA-registered reason 147 code. 149 o Reason Code (Variable): indicates the reasons/explanations of the 150 path status indicated in the Path Type field. The detailed Reason 151 Code field is defined in Section 2.2. 153 2.1. Path Status 155 The Path Status field contains a bit field where each bit encodes a 156 specific role of the path. Multiple bits may be set when multiple 157 path status apply to a path. 159 Two encoding options for Path Status are described in the following 160 two sections. 162 2.1.1. IANA-registered Path Status Encoding 164 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 165 +-------------------------------+ 166 |E| IANA registered path status | 167 +-------------------------------+ 169 Figure 2: IANA-registered encoding of Path Status 171 o E bit (1 Bit): set to 0, indicating that only IANA-registered path 172 status is used in this TLV. 174 o IANA-registered Path Status (2 octets): indicates the IANA- 175 registered path status, as specified in Table 1. 177 +--------+----------------------+ 178 | Value | Path type | 179 +-------------------------------+ 180 | 0x0000 | Unknown | 181 | 0x0001 | Invalid | 182 | 0x0002 | Best | 183 | 0x0004 | Non-selected | 184 | 0x0008 | Primary | 185 | 0x0010 | Backup | 186 | 0x0020 | Non-installed | 187 | 0x0040 | Best external | 188 | 0x0080 | Add-Path | 189 +--------+----------------------+ 191 Table 1: Path Type 193 The best-path is defined in RFC4271 [RFC4271] and the best-external 194 path is defined in draft-ietf-idr-best-external 195 [I-D.ietf-idr-best-external]. 197 An invalid path is a route that does not enter the BGP decision 198 process. 200 A non-selected path is a route that is not selected in the BGP 201 decision process. In other words, Best route and ECMP routes are not 202 considered as non-selected. 204 A primary path is a recursive or non-recursive path whose nexthop 205 resolution ends with an adjacency draft-ietf-rtgwg-bgp-pic 206 [I-D.ietf-rtgwg-bgp-pic]. A prefix can have more than one primary 207 path if multipath is configured draft-lapukhov-bgp-ecmp- 208 considerations [I-D.lapukhov-bgp-ecmp-considerations]. A best-path 209 is also considered as a primary path. 211 A backup path is also installed in the RIB, but it is not used until 212 some or all primary paths become unreachable. Backup paths are used 213 for fast convergence in the event of failures. 215 A non-installed path refers to the route that is not installed into 216 the IP routing table. 218 For the advertisement of multiple paths for the same address prefix 219 without the new paths implicitly replacing any previous ones, the 220 add-path status is applied RFC7911 [RFC7911]. 222 2.1.2. Enterprise-specific Path Status Encoding 224 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 1 225 +---------------------------------------------------------------+ 226 |E| Enterprise-Specific Path Type (4 octets) | 227 +---------------------------------------------------------------+ 228 | Enterprise Number(4 octets) | 229 +---------------------------------------------------------------+ 231 Figure 3: Enterprise-specific encoding of Path Status 233 o E bit (1 Bit): set to 1, indicating enterprise-specific path 234 status is used in this TLV. 236 o Enterprise-specific Path Type (4 octets): indicates enterprise- 237 specific path status, which remains to be defined. 239 o Enterprise Number (4 octets): indicates the IANA enterprise number 240 IANA-PEN. 242 2.2. Reason Code 244 The Reason Code field contains a bit field where each bit encodes a 245 specific reason. Multiple bits may be set when multiple reasons 246 apply to a path. 248 2.2.1. IANA-registered Reason Code Encoding 250 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 1 251 +---------------------------------------------------------------+ 252 |E| IANA-registered Reason Code(4 octets) | 253 +---------------------------------------------------------------+ 255 Figure 4: IANA-registered encoding of Reason Code 257 o E bit (1 Bit): set to 0, indicating that only IANA-registered 258 reason code is used in this TLV. With the E bit set to 0, the 259 Length field of the Path Marking TLV SHOULD be set to 8. 261 o IANA-registered Reason Code (4 octets): indicates the IANA- 262 registered reason code of the path status. 264 2.2.2. Enterprise-specific Reason Code Encoding 266 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 1 267 +---------------------------------------------------------------+ 268 |E| Enterprise Number(4 octets) | 269 +---------------------------------------------------------------+ 270 + E-specific Reason Code(variable) + 271 ~ ~ 272 +---------------------------------------------------------------+ 274 Figure 5: Enterprise-specific encoding of Reason Code 276 o E bit (1 Bit): set to 1, indicating enterprise-specific reason 277 code is also used in this TLV. 279 o IANA-registered Reason Code (4 octets): indicates the IANA- 280 registered reason code of the path status. 282 o Enterprise Number (4 octets): indicates the IANA enterprise number 283 IANA-PEN. 285 o E-specific Reason Code (Variable): indicates enterprise-specific 286 reason code of the path status. 288 3. Acknowledgements 290 We would like to thank Jeff Haas for his valuable comments. 292 4. IANA Considerations 294 This document requests that IANA assign the following new parameters 295 to the BMP parameters name space. 297 4.1. Path Marking TLV 299 This document defines the Path Marking TLV with Type = TBD1: Path 300 Marking (Section 2). 302 4.2. Path Marking TLV Reason Code 304 5. Security Considerations 306 It is not believed that this document adds any additional security 307 considerations. 309 6. Normative References 311 [I-D.ietf-idr-best-external] 312 Marques, P., Fernando, R., Chen, E., Mohapatra, P., and H. 313 Gredler, "Advertisement of the best external route in 314 BGP", draft-ietf-idr-best-external-05 (work in progress), 315 January 2012. 317 [I-D.ietf-rtgwg-bgp-pic] 318 Bashandy, A., Filsfils, C., and P. Mohapatra, "BGP Prefix 319 Independent Convergence", draft-ietf-rtgwg-bgp-pic-10 320 (work in progress), October 2019. 322 [I-D.lapukhov-bgp-ecmp-considerations] 323 Lapukhov, P. and J. Tantsura, "Equal-Cost Multipath 324 Considerations for BGP", draft-lapukhov-bgp-ecmp- 325 considerations-03 (work in progress), November 2019. 327 [I-D.lucente-bmp-tlv] 328 Lucente, P., Gu, Y., and H. Smit, "TLV support for BMP 329 Route Monitoring and Peer Down Messages", draft-lucente- 330 bmp-tlv-00 (work in progress), July 2019. 332 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 333 Requirement Levels", BCP 14, RFC 2119, 334 DOI 10.17487/RFC2119, March 1997, 335 . 337 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 338 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 339 DOI 10.17487/RFC4271, January 2006, 340 . 342 [RFC7854] Scudder, J., Ed., Fernando, R., and S. Stuart, "BGP 343 Monitoring Protocol (BMP)", RFC 7854, 344 DOI 10.17487/RFC7854, June 2016, 345 . 347 [RFC7911] Walton, D., Retana, A., Chen, E., and J. Scudder, 348 "Advertisement of Multiple Paths in BGP", RFC 7911, 349 DOI 10.17487/RFC7911, July 2016, 350 . 352 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 353 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 354 May 2017, . 356 Authors' Addresses 358 Camilo Cardona 359 NTT 360 164-168, Carrer de Numancia 361 Barcelona 08029 362 Spain 364 Email: camilo@ntt.net 366 Paolo Lucente 367 NTT 368 Siriusdreef 70-72 369 Hoofddorp, WT 2132 370 Netherlands 372 Email: paolo@ntt.net 374 Pierre Francois 375 INSA-Lyon 376 Lyon 377 France 379 Email: Pierre.Francois@insa-lyon.fr 380 Yunan Gu 381 Huawei 382 Huawei Bld., No.156 Beiqing Rd. 383 Beijing 100095 384 China 386 Email: guyunan@huawei.com 388 Thomas Graf 389 Swisscom 390 Binzring 17 391 Zurich 8045 392 Switzerland 394 Email: thomas.graf@swisscom.com