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'I-D.ietf-idr-best-external' == Outdated reference: A later version (-20) exists of draft-ietf-rtgwg-bgp-pic-11 ** Downref: Normative reference to an Informational draft: draft-ietf-rtgwg-bgp-pic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 'I-D.ietf-rtgwg-bgp-pic') == Outdated reference: A later version (-12) exists of draft-lapukhov-bgp-ecmp-considerations-03 ** Downref: Normative reference to an Informational draft: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 'I-D.lapukhov-bgp-ecmp-considerations') == Outdated reference: A later version (-02) exists of draft-lucente-grow-bmp-tlv-ebit-00 Summary: 3 errors (**), 0 flaws (~~), 6 warnings (==), 2 comments (--).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: September 9, 2020 P. Francois 6 INSA-Lyon 7 Y. Gu 8 Huawei 9 T. Graf 10 Swisscom 11 March 08, 2020 13 BMP Extension for Path Marking TLV 14 draft-cppy-grow-bmp-path-marking-tlv-03 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-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 September 9, 2020. 51 Copyright Notice 53 Copyright (c) 2020 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 58 (https://trustee.ietf.org/license-info) in effect on the date of 59 publication of this document. Please review these documents 60 carefully, as they describe your rights and restrictions with respect 61 to this document. Code Components extracted from this document must 62 include Simplified BSD License text as described in Section 4.e of 63 the Trust Legal Provisions and are provided without warranty as 64 described in the Simplified BSD License. 66 Table of Contents 68 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 69 2. Prefix Information TLV for the RM Message . . . . . . . . . . 3 70 3. Path Marking sub-TLV . . . . . . . . . . . . . . . . . . . . 3 71 3.1. IANA-registered Path Markinig sub-TLV . . . . . . . . . . 4 72 3.2. Enterprise-specific Path Marking sub-TLV . . . . . . . . 6 73 4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 74 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 75 6. Security Considerations . . . . . . . . . . . . . . . . . . . 7 76 7. Normative References . . . . . . . . . . . . . . . . . . . . 7 77 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 79 1. Introduction 81 For a given prefix, multiple paths with different path status, e.g., 82 the "best-path", "back-up path" and so on, may co-exist in the BGP 83 RIB after being processed by the local policy and the BGP decision 84 process. The path status information is currently not carried in the 85 BGP Update Message RFC4271 [RFC4271] or in the BMP Update Message 86 RFC7854 [RFC7854]. 88 External systems can use the path status for various applications. 89 The path status is commonly checked by operators when performing 90 troubleshooting. Having such status stored in a centralized system 91 can enable the development of tools facilitating this process. 92 Optimisation systems can include the path status in their process, 93 and also use the status as a validation source (since it can compare 94 the calculated state to the actual outcome of the network, such as 95 primary and backup path). As a final example, path status 96 information can complement other centralized sources of data, for 97 example, flow collectors. 99 This document defines a so-called Path Marking TLV to convey the BGP 100 path status information to the BMP server. The BMP Path Marking is 101 defined to be prepended in the BMP Route Monitoring (RM) Message. 103 2. Prefix Information TLV for the RM Message 105 As per RFC7854 [RFC7854], the BMP RM Message consists of the Common 106 Header, Per-Peer Header, and the BGP Update PDU. According to draft- 107 grow-bmp-tlv [I-D.ietf-grow-bmp-tlv] , optional trailing data in TLV 108 format is allowed in the BMP RM Message to convey characteristics of 109 transported NLRIs (i.e. to help stateless parsing) or vendor-specific 110 data. Such TLV types are to be defined for each application. 112 This document defines the Prefix Information TLV to convey 113 descriptional information for route prefixes. The format is shown 114 below. 116 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 1 117 +-------------------------------+-------------------------------+ 118 | Type (2 octets) | Length (2 octets) | 119 +---------------------------------------------------------------+ 120 | Count (2 octets) | 121 +-------------------------------+-------------------------------+ 122 | Prefix information value(variable) | 123 +---------------------------------------------------------------+ 125 Figure 1: Prefix Information TLV 127 o Type = TBD1 (2 Octets): Prefix Information TLV. 129 o Length (2 Octets): indicates the length of the value field of the 130 Prefix Information TLV. 132 o Count (2 Octets): indicates the number of sub TLVs followed in the 133 Prefix Information Value field. 135 o Prefix information value (Variable): indicates the value of the 136 Prefix Informtion TLV, which consists of one or multiple sub TLVs. 138 3. Path Marking sub-TLV 140 As stated in Appendix F.1 of RFC4271 [RFC4271], multiple address 141 prefixes with the same path attributes are allowed to be specified in 142 one message. However, such multiple prefixes may have different 143 prefix information, e.g., path status. Thus, to indicate the path 144 status for each BGP prefix, we define the Path Marking sub-TLV. The 145 order of the Path Marking sub-TLVs MUST be in accordance with the 146 prefix order of the Update PDU. 148 The E-bit [I-D.lucente-grow-bmp-tlv-ebit] mechanism allows the usage 149 of vendor-specific TLVs in addition to IANA-registered one. In this 150 document, both encoding options for the Path Marking sub-TLV are 151 described. 153 3.1. IANA-registered Path Markinig sub-TLV 155 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 1 156 +-------------------------------+-------------------------------+ 157 |E| Type (15 bits) | Length (2 octets) | 158 +-------------------------------+-------------------------------+ 159 | Path Status(4 octets) | 160 +---------------------------------------------------------------+ 161 | Reason Code(4 octets) | 162 +---------------------------------------------------------------+ 164 Figure 2:IANA-Registered Encoding of Path Marking sub-TLV 166 o E bit: For an IANA-registered sub-TLV, the E bit MUST be set to 0. 168 o Type = TBD2 (15 Bits): Path Marking sub-TLV. 170 o Length (2 Octets): indicates the length of the value field of the 171 Path Marking TLV. The value field further consists of the Path- 172 Status field and Reason Code field. 174 o Path Status (4 Octets): indicates the path status of the BGP 175 Update PDU encapsulated in the RM Message. Currently 9 types of 176 path status are defined, as shown in Table 1. 178 o Reason Code (4 Octets): indicates the reasons/explanations of the 179 path status indicated in the Path Type field. The detailed Reason 180 Code bitmap remains to be defined. 182 +------------+------------------+ 183 | Value | Path type | 184 +-------------------------------+ 185 | 0x00000000 | Unknown | 186 | 0x00000001 | Invalid | 187 | 0x00000002 | Best | 188 | 0x00000004 | Non-selected | 189 | 0x00000008 | Primary | 190 | 0x00000010 | Backup | 191 | 0x00000020 | Non+installed | 192 | 0x00000040 | Best external | 193 | 0x00000080 | Add-Path | 194 +------------+------------------+ 196 Table 1: IANA-Registered Path Type 198 The Path Status field contains a bitmap where each bit encodes a 199 specific role of the path. Multiple bits may be set when multiple 200 path status apply to a path. 202 o The best-path is defined in RFC4271 [RFC4271] and the best- 203 external path is defined in draft-ietf-idr-best-external 204 [I-D.ietf-idr-best-external]. 206 o An invalid path is a route that does not enter the BGP decision 207 process. 209 o A non-selected path is a route that is not selected in the BGP 210 decision process. Back-up routes are considered non-selected, 211 while the best and ECMP routes are not considered as non-selected. 213 o A primary path is a recursive or non-recursive path whose nexthop 214 resolution ends with an adjacency draft-ietf-rtgwg-bgp-pic 215 [I-D.ietf-rtgwg-bgp-pic]. A prefix can have more than one primary 216 path if multipath is configured draft-lapukhov-bgp-ecmp- 217 considerations [I-D.lapukhov-bgp-ecmp-considerations]. A best- 218 path is also considered as a primary path. 220 o A backup path is also installed in the RIB, but it is not used 221 until some or all primary paths become unreachable. Backup paths 222 are used for fast convergence in the event of failures. 224 o A non-installed path refers to the route that is not installed 225 into the IP routing table. 227 o For the advertisement of multiple paths for the same address 228 prefix without the new paths implicitly replacing any previous 229 ones, the add-path status is applied RFC7911 [RFC7911]. 231 3.2. Enterprise-specific Path Marking sub-TLV 233 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 1 234 +-------------------------------+-------------------------------+ 235 |E| Type (15 bits) | Length (2 octets) | 236 +-------------------------------+-------------------------------+ 237 | PEN number (4 octets) | 238 +---------------------------------------------------------------+ 239 | Path Status(4 octets) | 240 +---------------------------------------------------------------+ 241 | Reason Code(variable) | 242 +---------------------------------------------------------------+ 244 Figure 3: Enterprise-specific encoding of Path Markiing sub-TLV 246 o E bit: For an Enterprise-specific sub-TLV, the E bit MUST be set 247 to 1. 249 o Type = 1 (15 Bits): indicates that it's the Enterprise-specific 250 Path Marking sub-TLV. 252 o Length (2 Octets): indicates the length of the value field of the 253 Path Marking TLV. The value field further consists of the Path- 254 Status field and Reason Code field. 256 o PEN Number (4 octets): indicates the IANA enterprise number IANA- 257 PEN. 259 o Path Status (4 Octets): indicates enterprise-specific path status, 260 which remains to be defined. 262 o Reason Code (Variable): indicates the reasons/explanations of the 263 path status indicated in the Path Type field. The detailed Reason 264 Code string is to be defined. 266 4. Acknowledgements 268 We would like to thank Jeff Haas for his valuable comments. 270 5. IANA Considerations 272 This document requests that IANA assign the following new parameters 273 to the BMP parameters name space. 275 Type = TBD1 (2 Octets): Prefix Information TLV. 277 Type = TBD2 (15 Bits): Path Marking sub-TLV. 279 6. Security Considerations 281 It is not believed that this document adds any additional security 282 considerations. 284 7. Normative References 286 [I-D.ietf-grow-bmp-tlv] 287 Lucente, P., Gu, Y., and H. Smit, "TLV support for BMP 288 Route Monitoring and Peer Down Messages", draft-ietf-grow- 289 bmp-tlv-01 (work in progress), October 2019. 291 [I-D.ietf-idr-best-external] 292 Marques, P., Fernando, R., Chen, E., Mohapatra, P., and H. 293 Gredler, "Advertisement of the best external route in 294 BGP", draft-ietf-idr-best-external-05 (work in progress), 295 January 2012. 297 [I-D.ietf-rtgwg-bgp-pic] 298 Bashandy, A., Filsfils, C., and P. Mohapatra, "BGP Prefix 299 Independent Convergence", draft-ietf-rtgwg-bgp-pic-11 300 (work in progress), February 2020. 302 [I-D.lapukhov-bgp-ecmp-considerations] 303 Lapukhov, P. and J. Tantsura, "Equal-Cost Multipath 304 Considerations for BGP", draft-lapukhov-bgp-ecmp- 305 considerations-03 (work in progress), November 2019. 307 [I-D.lucente-grow-bmp-tlv-ebit] 308 Lucente, P. and Y. Gu, "Support for Enterprise-specific 309 TLVs in the BGP Monitoring Protocol", draft-lucente-grow- 310 bmp-tlv-ebit-00 (work in progress), November 2019. 312 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 313 Requirement Levels", BCP 14, RFC 2119, 314 DOI 10.17487/RFC2119, March 1997, 315 . 317 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 318 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 319 DOI 10.17487/RFC4271, January 2006, 320 . 322 [RFC7854] Scudder, J., Ed., Fernando, R., and S. Stuart, "BGP 323 Monitoring Protocol (BMP)", RFC 7854, 324 DOI 10.17487/RFC7854, June 2016, 325 . 327 [RFC7911] Walton, D., Retana, A., Chen, E., and J. Scudder, 328 "Advertisement of Multiple Paths in BGP", RFC 7911, 329 DOI 10.17487/RFC7911, July 2016, 330 . 332 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 333 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 334 May 2017, . 336 Authors' Addresses 338 Camilo Cardona 339 NTT 340 164-168, Carrer de Numancia 341 Barcelona 08029 342 Spain 344 Email: camilo@ntt.net 346 Paolo Lucente 347 NTT 348 Siriusdreef 70-72 349 Hoofddorp, WT 2132 350 Netherlands 352 Email: paolo@ntt.net 354 Pierre Francois 355 INSA-Lyon 356 Lyon 357 France 359 Email: Pierre.Francois@insa-lyon.fr 361 Yunan Gu 362 Huawei 363 Huawei Bld., No.156 Beiqing Rd. 364 Beijing 100095 365 China 367 Email: guyunan@huawei.com 368 Thomas Graf 369 Swisscom 370 Binzring 17 371 Zurich 8045 372 Switzerland 374 Email: thomas.graf@swisscom.com