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'I-D.lapukhov-bgp-ecmp-considerations') == Outdated reference: A later version (-02) exists of draft-lucente-grow-bmp-tlv-ebit-01 Summary: 3 errors (**), 0 flaws (~~), 7 warnings (==), 2 comments (--).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: January 13, 2021 P. Francois 6 INSA-Lyon 7 Y. Gu 8 Huawei 9 T. Graf 10 Swisscom 11 July 12, 2020 13 BMP Extension for Path Status sub-TLV 14 draft-cppy-grow-bmp-path-marking-tlv-04 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 Path Information TLV defined in draft-cppy-grow-bmp- 24 path-info-tlv [I-D.cppy-grow-bmp-path-info-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 January 13, 2021. 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 Status sub-TLV . . . . . . . . . . . . . . . . . . . . . 3 69 2.1. IANA-registered Path Status sub-TLV . . . . . . . . . . . 3 70 2.2. Enterprise-specific Path Status sub-TLV . . . . . . . . . 6 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 sub-TLV to convey the 98 BGP path status to the BMP server. The BMP Path Status sub-TLV is 99 encapsulated within the BMP Path Information TLV carried in the BMP 100 Route Monitoring (RM) Message draft-cppy-grow-bmp-path-info-tlv 101 [I-D.cppy-grow-bmp-path-info-tlv]. 103 2. Path Status sub-TLV 105 As stated in draft-cppy-grow-bmp-path-info-tlv 106 [I-D.cppy-grow-bmp-path-info-tlv], the order of the sub-TLVs MUST be 107 in accordance with the prefix order encapsulated in the Update PDU. 108 This document defines two types of Path Status sub-TLVs: one is IANA- 109 registered Path Status sub-TLV, and the other is Enterprise-specific 110 Path Status sub-TLV. 112 2.1. IANA-registered Path Status sub-TLV 114 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 1 115 +-------------------------------+-------------------------------+ 116 |E| Type (15 bits) | Length (2 octets) | 117 +-------------------------------+-------------------------------+ 118 | Path Status(4 octets) | 119 +---------------------------------------------------------------+ 120 | Reason Code(4 octets) | 121 +---------------------------------------------------------------+ 123 Figure 2:IANA-Registered Encoding of the path status sub-TLV 125 o E bit: For an IANA-registered sub-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 sub-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 Path Status (4 Octets): indicates the path status of the BGP 135 Update PDU encapsulated in the RM Message. Currently 9 types of 136 path status are defined, as shown in Table 1. 138 o Reason Code (4 Octets): indicates the reasons/explanations of the 139 path status indicated in the Path Type field. The currently 140 defined reason codes are shown in Table 2. 142 +------------+------------------+ 143 | Value | Path type | 144 +-------------------------------+ 145 | 0x00000000 | Unknown | 146 | 0x00000001 | Invalid | 147 | 0x00000002 | Best | 148 | 0x00000004 | Non-selected | 149 | 0x00000008 | Primary | 150 | 0x00000010 | Backup | 151 | 0x00000020 | Non-installed | 152 | 0x00000040 | Best-external | 153 | 0x00000080 | Add-Path | 154 +------------+------------------+ 156 Table 1: IANA-Registered Path Type 158 The Path Status field contains a bitmap where each bit encodes a 159 specific role of the path. Multiple bits may be set when multiple 160 path status apply to a path. 162 o The best-path is defined in RFC4271 [RFC4271] and the best- 163 external path is defined in draft-ietf-idr-best-external 164 [I-D.ietf-idr-best-external]. 166 o An invalid path is a route that does not enter the BGP decision 167 process. 169 o A non-selected path is a route that is not selected in the BGP 170 decision process. Back-up routes are considered non-selected, 171 while the best and ECMP routes are not considered as non-selected. 173 o A primary path is a recursive or non-recursive path whose nexthop 174 resolution ends with an adjacency draft-ietf-rtgwg-bgp-pic 175 [I-D.ietf-rtgwg-bgp-pic]. A prefix can have more than one primary 176 path if multipath is configured draft-lapukhov-bgp-ecmp- 177 considerations [I-D.lapukhov-bgp-ecmp-considerations]. A best- 178 path is also considered as a primary path. 180 o A backup path is also installed in the RIB, but it is not used 181 until some or all primary paths become unreachable. Backup paths 182 are used for fast convergence in the event of failures. 184 o A non-installed path refers to the route that is not installed 185 into the IP routing table. 187 o For the advertisement of multiple paths for the same address 188 prefix without the new paths implicitly replacing any previous 189 ones, the add-path status is applied RFC7911 [RFC7911]. 191 +-------------+--------------------------------------------------- 192 | value | reason code | 193 +----------------------------------------------------------------+ 194 |[0x00000000] |invalid for unknown, | 195 |[0x00000001] |invalid for super network, | 196 |[0x00000002] |invalid for dampening, | 197 |[0x00000003] |invalid for history, | 198 |[0x00000004] |invalid for policy deny, | 199 |[0x00000005] |invalid for ROA not validation, | 200 |[0x00000006] |invalid for interface error, | 201 |[0x00000007] |invalid for nexthop route unreachable, | 202 |[0x00000008] |invalid for nexthop tunnel unreachable, | 203 |[0x0000000f] |invalid for nexthop restrain, | 204 |[0x00000010] |invalid for relay BGP LSP, | 205 |[0x00000014] |invalid for being inactive within VPN instance | 206 |[0x00000015] |invalid for prefix-sid not exist, | 207 |[0x00000200] |not preferred for peer address, | 208 |[0x00000300] |not preferred for router ID, | 209 |[0x00000400] |not preferred for Cluster List, | 210 |[0x00000500] |not preferred for IGP cost, | 211 |[0x00000600] |not preferred for peer type, | 212 |[0x00000700] |not preferred for MED, | 213 |[0x00000800] |not preferred for origin, | 214 |[0x00000900] |not preferred for AS-Path, | 215 |[0x00000a00] |not preferred for route type, | 216 |[0x00000b00] |not preferred for Local_Pref, | 217 |[0x00000c00] |not preferred for PreVal, | 218 |[0x00000f00] |not preferred for not direct route, | 219 |[0x00001000] |not preferred for nexthop bit error, | 220 |[0x00001100] |not preferred for received path-id, | 221 |[0x00001200] |not preferred for validation, | 222 |[0x00001300] |not preferred for originate IP, | 223 |[0x00001500] |not preferred for route distinguisher, | 224 |[0x00001600] |not preferred for route-select delay, | 225 |[0x00001700] |not preferred for being imported route, | 226 |[0x00001800] |not preferred for med-plus-igp, | 227 |[0x00001c00] |not preferred for AIGP, | 228 |[0x00001d00] |not preferred for nexthop-resolved aigp, | 229 |[0x00002000] |not preferred for nexthop unreachable, | 230 |[0x00002100] |not preferred for nexthop IP, | 231 |[0x00002300] |not preferred for high-priority, | 232 |[0x00002400] |not preferred for nexthop-priority, | 233 |[0x00002500] |not preferred for process ID, | 234 |[0xFFFFFFFF] |no reason code | 235 -----------------------------------------------------------------+ 237 Table 2: IANA-Registered Reason Code 239 2.2. Enterprise-specific Path Status sub-TLV 241 The E-bit [I-D.lucente-grow-bmp-tlv-ebit] mechanism allows the usage 242 of vendor-specific TLVs in addition to IANA-registered one. In this 243 document, both encoding options for the Path Status sub-TLV are 244 described. 246 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 1 247 +-------------------------------+-------------------------------+ 248 |E| Type (15 bits) | Length (2 octets) | 249 +-------------------------------+-------------------------------+ 250 | PEN number (4 octets) | 251 +---------------------------------------------------------------+ 252 | Path Status(4 octets) | 253 +---------------------------------------------------------------+ 254 | Reason Code(variable) | 255 +---------------------------------------------------------------+ 257 Figure 3: Enterprise-specific encoding of Path Status sub-TLV 259 o E bit: For an Enterprise-specific sub-TLV, the E bit MUST be set 260 to 1. 262 o Type = 1 (15 Bits): indicates that it's the Enterprise-specific 263 Path Status sub-TLV. 265 o Length (2 Octets): indicates the length of the value field of the 266 Path Status sub-TLV. The value field further consists of the 267 Path-Status field and Reason Code field. 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. 275 o Reason Code (Variable): indicates the reasons/explanations of the 276 path status indicated in the Path Type field. 278 3. Acknowledgments 280 We would like to thank Jeff Haas for his valuable comments. 282 4. IANA Considerations 284 This document requests that IANA assign the following new parameters 285 to the BMP parameters name space. 287 Type = TBD1 (15 Bits): indicates that it is the IANA-registered Path 288 Status sub-TLV. 290 5. Security Considerations 292 It is not believed that this document adds any additional security 293 considerations. 295 6. Normative References 297 [I-D.cppy-grow-bmp-path-info-tlv] 298 Cardona, C., Lucente, P., Francois, P., Gu, Y., and T. 299 Graf, "BMP Extension for Path Information TLV", draft- 300 cppy-grow-bmp-path-info-tlv-00 (work in progress), July 301 2020. 303 [I-D.ietf-grow-bmp-tlv] 304 Lucente, P., Gu, Y., and H. Smit, "TLV support for BMP 305 Route Monitoring and Peer Down Messages", draft-ietf-grow- 306 bmp-tlv-02 (work in progress), March 2020. 308 [I-D.ietf-idr-best-external] 309 Marques, P., Fernando, R., Chen, E., Mohapatra, P., and H. 310 Gredler, "Advertisement of the best external route in 311 BGP", draft-ietf-idr-best-external-05 (work in progress), 312 January 2012. 314 [I-D.ietf-rtgwg-bgp-pic] 315 Bashandy, A., Filsfils, C., and P. Mohapatra, "BGP Prefix 316 Independent Convergence", draft-ietf-rtgwg-bgp-pic-11 317 (work in progress), February 2020. 319 [I-D.lapukhov-bgp-ecmp-considerations] 320 Lapukhov, P. and J. Tantsura, "Equal-Cost Multipath 321 Considerations for BGP", draft-lapukhov-bgp-ecmp- 322 considerations-04 (work in progress), May 2020. 324 [I-D.lucente-grow-bmp-tlv-ebit] 325 Lucente, P. and Y. Gu, "Support for Enterprise-specific 326 TLVs in the BGP Monitoring Protocol", draft-lucente-grow- 327 bmp-tlv-ebit-01 (work in progress), May 2020. 329 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 330 Requirement Levels", BCP 14, RFC 2119, 331 DOI 10.17487/RFC2119, March 1997, 332 . 334 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 335 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 336 DOI 10.17487/RFC4271, January 2006, 337 . 339 [RFC7854] Scudder, J., Ed., Fernando, R., and S. Stuart, "BGP 340 Monitoring Protocol (BMP)", RFC 7854, 341 DOI 10.17487/RFC7854, June 2016, 342 . 344 [RFC7911] Walton, D., Retana, A., Chen, E., and J. Scudder, 345 "Advertisement of Multiple Paths in BGP", RFC 7911, 346 DOI 10.17487/RFC7911, July 2016, 347 . 349 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 350 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 351 May 2017, . 353 Authors' Addresses 355 Camilo Cardona 356 NTT 357 164-168, Carrer de Numancia 358 Barcelona 08029 359 Spain 361 Email: camilo@ntt.net 363 Paolo Lucente 364 NTT 365 Siriusdreef 70-72 366 Hoofddorp, WT 2132 367 Netherlands 369 Email: paolo@ntt.net 371 Pierre Francois 372 INSA-Lyon 373 Lyon 374 France 376 Email: Pierre.Francois@insa-lyon.fr 377 Yunan Gu 378 Huawei 379 Huawei Bld., No.156 Beiqing Rd. 380 Beijing 100095 381 China 383 Email: guyunan@huawei.com 385 Thomas Graf 386 Swisscom 387 Binzring 17 388 Zurich 8045 389 Switzerland 391 Email: thomas.graf@swisscom.com