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'I-D.ietf-idr-best-external' == Outdated reference: A later version (-20) exists of draft-ietf-rtgwg-bgp-pic-12 ** Downref: Normative reference to an Informational draft: draft-ietf-rtgwg-bgp-pic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 'I-D.ietf-rtgwg-bgp-pic') == Outdated reference: A later version (-12) exists of draft-lapukhov-bgp-ecmp-considerations-04 ** Downref: Normative reference to an Informational draft: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 'I-D.lapukhov-bgp-ecmp-considerations') == Outdated reference: A later version (-02) exists of draft-lucente-grow-bmp-tlv-ebit-01 Summary: 3 errors (**), 0 flaws (~~), 40 warnings (==), 2 comments (--).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: March 27, 2021 P. Francois 6 INSA-Lyon 7 Y. Gu 8 Huawei 9 T. Graf 10 Swisscom 11 September 23, 2020 13 BMP Extension for Path Status TLV 14 draft-cppy-grow-bmp-path-marking-tlv-05 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 March 27, 2021. 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. 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 ~ ~ 119 | Reason Code(variable) | 120 ~ ~ 121 +---------------------------------------------------------------+ 123 Figure 2: Encoding of IANA-Registered Path Status TLV 125 o E bit: For an IANA-registered TLV, the E bit MUST be set to 0. 127 o Type = TBD2 (15 Bits): indicates that it is the IANA-registered 128 Path Status TLV. 130 o Length (2 Octets): indicates the length of the value field of the 131 Path Status TLV. The value field further consists of the Path- 132 Status field and Reason Code field. 134 o Index (2 Octets): indicates the encapsulation order of the prefix, 135 in the BGP Update PDU, that the this sub TLV is describing 136 information for. 138 o Path Status (4 Octets): indicates the path status of the BGP 139 Update PDU encapsulated in the RM Message. Currently 8 types of 140 path status are defined, as shown in Table 1. All zeros are 141 reserved. 143 o Reason Code (variable): indicates the reasons/explanations of the 144 path status indicated in the Path Status field. The reason code 145 field is optional. If no reason code is carried, this field is 146 empty. If a reason code is carried, the reason code is indicated 147 by a 2-byte value, which is defined in Table 2. 149 +------------+------------------+ 150 | Value | Path type | 151 +-------------------------------+ 152 | 0x00000001 | Invalid | 153 | 0x00000002 | Best | 154 | 0x00000004 | Non-selected | 155 | 0x00000008 | Primary | 156 | 0x00000010 | Backup | 157 | 0x00000020 | Non-installed | 158 | 0x00000040 | Best-external | 159 | 0x00000080 | Add+Path | 160 +------------+------------------+ 162 Table 1: IANA-Registered Path Type 164 The Path Status field contains a bitmap where each bit encodes a 165 specific role of the path. 167 o The best-path is defined in RFC4271 [RFC4271] and the best- 168 external path is defined in draft-ietf-idr-best-external 169 [I-D.ietf-idr-best-external]. 171 o An invalid path is a route that does not enter the BGP decision 172 process. 174 o A non-selected path is a route that is not selected in the BGP 175 decision process. Back-up routes are considered non-selected, 176 while the best and ECMP routes are not considered as non-selected. 178 o A primary path is a recursive or non-recursive path whose nexthop 179 resolution ends with an adjacency draft-ietf-rtgwg-bgp-pic 180 [I-D.ietf-rtgwg-bgp-pic]. A prefix can have more than one primary 181 path if multipath is configured draft-lapukhov-bgp-ecmp- 182 considerations [I-D.lapukhov-bgp-ecmp-considerations]. A best- 183 path is also considered as a primary path. 185 o A backup path is also installed in the RIB, but it is not used 186 until some or all primary paths become unreachable. Backup paths 187 are used for fast convergence in the event of failures. 189 o A non-installed path refers to the route that is not installed 190 into the IP routing table. 192 o For the advertisement of multiple paths for the same address 193 prefix without the new paths implicitly replacing any previous 194 ones, the add-path status is applied RFC7911 [RFC7911]. 196 +----------+-----------------------------------------------------+ 197 | Value | Reason code | 198 +----------------------------------------------------------------+ 199 | [0x0001] | invalid for super network | 200 | [0x0002] | invalid for dampening | 201 | [0x0003] | invalid for damping history | 202 | [0x0004] | invalid for policy deny | 203 | [0x0005] | invalid for ROV not valid | 204 | [0x0006] | invalid for interface error | 205 | [0x0007] | invalid for nexthop route unreachable | 206 | [0x0008] | invalid for nexthop tunnel unreachable | 207 | [0x0009] | invalid for nexthop restrain | 208 | [0x000A] | invalid for not supporting BGP LSP relay | 209 | [0x000B] | invalid for being inactive within VPN insance | 210 | [0x000C] | invalid for prefix sid not exist | 211 | [0x000D] | not preferred for peer address | 212 | [0x000E] | not preferred for router ID | 213 | [0x000F] | not preferred for Cluster List | 214 | [0x0010] | not preferred for IGP cost | 215 | [0x0011] | not preferred for peer type | 216 | [0x0012] | not preferred for MED | 217 | [0x0013] | not preferred for origin | 218 | [0x0014] | not preferred for AS Path | 219 | [0x0015] | not preferred for route type | 220 | [0x0016] | not preferred for Local preference | 221 | [0x0017] | not preferred for Weight | 222 | [0x0018] | not preferred for path to next hop with bit error | 223 | [0x0019] | not preferred for path id | 224 | [0x001A] | not preferred for ROV validation | 225 | [0x001B] | not preferred for originate IP | 226 | [0x001C] | not preferred for route distinguisher | 227 | [0x001D] | not preferred for delayed route selection | 228 | [0x001E] | not preferred for imported from other instances | 229 | [0x001F] | not preferred for med plus igp cost | 230 | [0x0020] | not preferred for AIGP | 231 | [0x0021] | not preferred for BGP LSP aigp for next hop relay | 232 | [0x0022] | not preferred for nexthop IP | 233 +----------+-----------------------------------------------------+ 235 Table 2: IANA-Registered Reason Code 237 2.2. Enterprise-specific Path Status TLV 239 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 1 240 +-------------------------------+-------------------------------+ 241 |E| Type (15 bits) | Length (2 octets) | 242 +---------------------------------------------------------------+ 243 | Index (2 octets) | 244 +-------------------------------+-------------------------------+ 245 | PEN number (4 octets) | 246 +---------------------------------------------------------------+ 247 | Path Status(4 octets) | 248 +---------------------------------------------------------------+ 249 ~ ~ 250 | Reason Code(variable) | 251 ~ ~ 252 +---------------------------------------------------------------+ 254 Figure 3: Encoding of Enterprise-specific Path Status TLV 256 o E bit: For an Enterprise-specific TLV, the E bit MUST be set to 1. 258 o Type = 1 (15 Bits): indicates that it's the Enterprise-specific 259 Path Status TLV. 261 o 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 o Index (2 Octets): indicates the encapsulation order of the prefix, 266 in the BGP Update PDU, that the this sub TLV is describing 267 information for. 269 o PEN Number (4 octets): indicates the IANA enterprise number IANA- 270 PEN. 272 o Path Status (4 Octets): indicates the enterprise-specific path 273 status. The format is to be determined w.r.t. each PEN number. 275 o Reason Code (Variable): indicates the reasons/explanations of the 276 path status indicated in the Path Status field. The format is to 277 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., Gu, Y., and H. Smit, "TLV support for BMP 300 Route Monitoring and Peer Down Messages", draft-ietf-grow- 301 bmp-tlv-03 (work in progress), September 2020. 303 [I-D.ietf-idr-best-external] 304 Marques, P., Fernando, R., Chen, E., Mohapatra, P., and H. 305 Gredler, "Advertisement of the best external route in 306 BGP", draft-ietf-idr-best-external-05 (work in progress), 307 January 2012. 309 [I-D.ietf-rtgwg-bgp-pic] 310 Bashandy, A., Filsfils, C., and P. Mohapatra, "BGP Prefix 311 Independent Convergence", draft-ietf-rtgwg-bgp-pic-12 312 (work in progress), August 2020. 314 [I-D.lapukhov-bgp-ecmp-considerations] 315 Lapukhov, P. and J. Tantsura, "Equal-Cost Multipath 316 Considerations for BGP", draft-lapukhov-bgp-ecmp- 317 considerations-04 (work in progress), May 2020. 319 [I-D.lucente-grow-bmp-tlv-ebit] 320 Lucente, P. and Y. Gu, "Support for Enterprise-specific 321 TLVs in the BGP Monitoring Protocol", draft-lucente-grow- 322 bmp-tlv-ebit-01 (work in progress), May 2020. 324 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 325 Requirement Levels", BCP 14, RFC 2119, 326 DOI 10.17487/RFC2119, March 1997, 327 . 329 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 330 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 331 DOI 10.17487/RFC4271, January 2006, 332 . 334 [RFC7854] Scudder, J., Ed., Fernando, R., and S. Stuart, "BGP 335 Monitoring Protocol (BMP)", RFC 7854, 336 DOI 10.17487/RFC7854, June 2016, 337 . 339 [RFC7911] Walton, D., Retana, A., Chen, E., and J. Scudder, 340 "Advertisement of Multiple Paths in BGP", RFC 7911, 341 DOI 10.17487/RFC7911, July 2016, 342 . 344 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 345 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 346 May 2017, . 348 Authors' Addresses 350 Camilo Cardona 351 NTT 352 164-168, Carrer de Numancia 353 Barcelona 08029 354 Spain 356 Email: camilo@ntt.net 358 Paolo Lucente 359 NTT 360 Siriusdreef 70-72 361 Hoofddorp, WT 2132 362 Netherlands 364 Email: paolo@ntt.net 366 Pierre Francois 367 INSA-Lyon 368 Lyon 369 France 371 Email: Pierre.Francois@insa-lyon.fr 372 Yunan Gu 373 Huawei 374 Huawei Bld., No.156 Beiqing Rd. 375 Beijing 100095 376 China 378 Email: guyunan@huawei.com 380 Thomas Graf 381 Swisscom 382 Binzring 17 383 Zurich 8045 384 Switzerland 386 Email: thomas.graf@swisscom.com