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'I-D.ietf-idr-best-external' == Outdated reference: A later version (-20) exists of draft-ietf-rtgwg-bgp-pic-12 ** Downref: Normative reference to an Informational draft: draft-ietf-rtgwg-bgp-pic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 'I-D.ietf-rtgwg-bgp-pic') == Outdated reference: A later version (-12) exists of draft-lapukhov-bgp-ecmp-considerations-05 ** Downref: Normative reference to an Informational draft: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 'I-D.lapukhov-bgp-ecmp-considerations') == Outdated reference: A later version (-02) exists of draft-lucente-grow-bmp-tlv-ebit-01 Summary: 3 errors (**), 0 flaws (~~), 40 warnings (==), 2 comments (--).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: October 29, 2021 P. Francois 6 INSA-Lyon 7 Y. Gu 8 Huawei 9 T. Graf 10 Swisscom 11 April 27, 2021 13 BMP Extension for Path Status TLV 14 draft-cppy-grow-bmp-path-marking-tlv-08 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 October 29, 2021. 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 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. Path Status TLV . . . . . . . . . . . . . . . . . . . . . . . 3 70 2.1. IANA-registered Path Status TLV . . . . . . . . . . . . . 3 71 2.2. Enterprise-specific Path Status TLV . . . . . . . . . . . 6 72 3. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6 73 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 74 5. Security Considerations . . . . . . . . . . . . . . . . . . . 7 75 6. Normative References . . . . . . . . . . . . . . . . . . . . 7 76 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 78 1. Introduction 80 For a given prefix, multiple paths with different path status, e.g., 81 the "best-path", "back-up path" and so on, may co-exist in the BGP 82 RIB after being processed by the local policy and the BGP decision 83 process. The path status information is currently not carried in the 84 BGP Update Message RFC4271 [RFC4271] or in the BMP Update Message 85 RFC7854 [RFC7854]. 87 External systems can use the path status for various applications. 88 The path status is commonly checked by operators when performing 89 troubleshooting. Having such status stored in a centralized system 90 can enable the development of tools that facilitate this process. 91 Optimisation systems can include the path status in their process, 92 and also use the status as a validation source (since it can compare 93 the calculated state to the actual outcome of the network, such as 94 primary and backup path). As a final example, path status 95 information can complement other centralized sources of data, for 96 example, flow collectors. 98 This document defines a so-called Path Status TLV to convey the BGP 99 path status to the BMP server. The BMP Path Status TLV is carried in 100 the BMP Route Monitoring (RM) Message. 102 2. Path Status TLV 104 This document defines two types of Path Status TLVs: one is the IANA- 105 registered Path Status TLV, and the other is the Enterprise-specific 106 Path Status TLV. 108 2.1. IANA-registered Path Status TLV 110 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 1 111 +-------------------------------+-------------------------------+ 112 |E| Type (15 bits) | Length (2 octets) | 113 +---------------------------------------------------------------+ 114 | Index (2 octets) | 115 +-------------------------------+-------------------------------+ 116 | Path Status (4 octets) | 117 +---------------------------------------------------------------+ 118 | Reason Code (2 octets, optional) | 119 +---------------------------------------------------------------+ 121 Figure 2: Encoding of IANA-Registered Path Status TLV 123 o E bit: For an IANA-registered TLV, the E bit MUST be set to 0. 125 o Type = TBD2 (15 Bits): indicates that it is the IANA-registered 126 Path Status TLV. 128 o Length (2 Octets): indicates the length of the value field of the 129 Path Status TLV. The value field further consists of the Path- 130 Status field and Reason Code field. 132 o Index (2 Octets): indicates the prefix that this TLV is 133 describing. The index is the encapsulation order, starting from 134 0, of the prefix in the BGP Update PDU. 136 o Path Status (4 Octets): indicates the path status of the BGP 137 Update PDU encapsulated in the RM Message. Currently 8 types of 138 path status are defined, as shown in Table 1. All zeros are 139 reserved. 141 o Reason Code (2 Octets, optional): indicates the reason of the path 142 status indicated in the Path Status field. The reason code field 143 is optional. If no reason code is carried, this field is empty. 144 If a reason code is carried, the reason code is indicated by a 145 2-byte value, which is defined in Table 2. 147 +------------+------------------+ 148 | Value | Path type | 149 +-------------------------------+ 150 | 0x00000001 | Invalid | 151 | 0x00000002 | Best | 152 | 0x00000004 | Non-selected | 153 | 0x00000008 | Primary | 154 | 0x00000010 | Backup | 155 | 0x00000020 | Non-installed | 156 | 0x00000040 | Best-external | 157 | 0x00000080 | Add-Path | 158 +------------+------------------+ 160 Table 1: IANA-Registered Path Type 162 The Path Status field contains a bitmap where each bit encodes a 163 specific role of the path. Multiple bits may be set when multiple 164 path status apply to a path. 166 o The best-path is defined in RFC4271 [RFC4271] and the best- 167 external path is defined in draft-ietf-idr-best-external 168 [I-D.ietf-idr-best-external]. 170 o An invalid path is a route that does not enter the BGP decision 171 process. 173 o A non-selected path is a route that is not selected in the BGP 174 decision process. Back-up routes are considered non-selected, 175 while the best and ECMP routes are not considered as non-selected. 177 o A primary path is a recursive or non-recursive path whose nexthop 178 resolution ends with an adjacency draft-ietf-rtgwg-bgp-pic 179 [I-D.ietf-rtgwg-bgp-pic]. A prefix can have more than one primary 180 path if multipath is configured draft-lapukhov-bgp-ecmp- 181 considerations [I-D.lapukhov-bgp-ecmp-considerations]. A best- 182 path is also considered as a primary path. 184 o 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 o A non-installed path refers to the route that is not installed 189 into the IP routing table. 191 o 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 242 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 1 243 +-------------------------------+-------------------------------+ 244 |E| Type (15 bits) | Length (2 octets) | 245 +-------------------------------+-------------------------------+ 246 | PEN number (4 octets) | 247 +---------------------------------------------------------------+ 248 | Index (2 octets) | 249 +---------------------------------------------------------------+ 250 | Path Status (4 octets) | 251 +---------------------------------------------------------------+ 252 | Reason Code (2 octets, optional) | 253 +---------------------------------------------------------------+ 255 Figure 3: Encoding of Enterprise-specific Path Status TLV 257 o E bit: For an Enterprise-specific TLV, the E bit MUST be set to 1. 259 o Type = 1 (15 Bits): indicates that it's the Enterprise-specific 260 Path Status TLV. 262 o Length (2 Octets): indicates the length of the value field of the 263 Path Status TLV. The value field further consists of the Path- 264 Status field and Reason Code field. 266 o Index (2 Octets): indicates the prefix that this TLV is 267 describing. The index is the encapsulation order, starting from 268 0, of the prefix in the BGP Update PDU. 270 o PEN Number (4 octets): indicates the IANA enterprise number IANA- 271 PEN. 273 o Path Status (4 Octets): indicates the enterprise-specific path 274 status. The format is to be determined w.r.t. each PEN number. 276 o Reason Code (2 octets, optional): indicates the reasons/ 277 explanations of the path status indicated in the Path Status 278 field. The format is to be determined w.r.t. each PEN number. 280 3. Acknowledgments 282 We would like to thank Jeff Haas for his valuable comments. 284 4. IANA Considerations 286 This document requests that IANA assign the following new parameters 287 to the BMP parameters name space. 289 Type = TBD1 (15 Bits): indicates that it is the IANA-registered Path 290 Status TLV. 292 5. Security Considerations 294 It is not believed that this document adds any additional security 295 considerations. 297 6. Normative References 299 [I-D.ietf-grow-bmp-tlv] 300 Lucente, P., Gu, Y., and H. Smit, "TLV support for BMP 301 Route Monitoring and Peer Down Messages", draft-ietf-grow- 302 bmp-tlv-04 (work in progress), November 2020. 304 [I-D.ietf-idr-best-external] 305 Marques, P., Fernando, R., Chen, E., Mohapatra, P., and H. 306 Gredler, "Advertisement of the best external route in 307 BGP", draft-ietf-idr-best-external-05 (work in progress), 308 January 2012. 310 [I-D.ietf-rtgwg-bgp-pic] 311 Bashandy, A., Filsfils, C., and P. Mohapatra, "BGP Prefix 312 Independent Convergence", draft-ietf-rtgwg-bgp-pic-12 313 (work in progress), August 2020. 315 [I-D.lapukhov-bgp-ecmp-considerations] 316 Lapukhov, P. and J. Tantsura, "Equal-Cost Multipath 317 Considerations for BGP", draft-lapukhov-bgp-ecmp- 318 considerations-05 (work in progress), November 2020. 320 [I-D.lucente-grow-bmp-tlv-ebit] 321 Lucente, P. and Y. Gu, "Support for Enterprise-specific 322 TLVs in the BGP Monitoring Protocol", draft-lucente-grow- 323 bmp-tlv-ebit-01 (work in progress), May 2020. 325 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 326 Requirement Levels", BCP 14, RFC 2119, 327 DOI 10.17487/RFC2119, March 1997, 328 . 330 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 331 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 332 DOI 10.17487/RFC4271, January 2006, 333 . 335 [RFC7854] Scudder, J., Ed., Fernando, R., and S. Stuart, "BGP 336 Monitoring Protocol (BMP)", RFC 7854, 337 DOI 10.17487/RFC7854, June 2016, 338 . 340 [RFC7911] Walton, D., Retana, A., Chen, E., and J. Scudder, 341 "Advertisement of Multiple Paths in BGP", RFC 7911, 342 DOI 10.17487/RFC7911, July 2016, 343 . 345 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 346 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 347 May 2017, . 349 Authors' Addresses 351 Camilo Cardona 352 NTT 353 164-168, Carrer de Numancia 354 Barcelona 08029 355 Spain 357 Email: camilo@ntt.net 359 Paolo Lucente 360 NTT 361 Siriusdreef 70-72 362 Hoofddorp, WT 2132 363 Netherlands 365 Email: paolo@ntt.net 367 Pierre Francois 368 INSA-Lyon 369 Lyon 370 France 372 Email: Pierre.Francois@insa-lyon.fr 373 Yunan Gu 374 Huawei 375 Huawei Bld., No.156 Beiqing Rd. 376 Beijing 100095 377 China 379 Email: guyunan@huawei.com 381 Thomas Graf 382 Swisscom 383 Binzring 17 384 Zurich 8045 385 Switzerland 387 Email: thomas.graf@swisscom.com