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'I-D.ietf-idr-best-external' == Outdated reference: A later version (-20) exists of draft-ietf-rtgwg-bgp-pic-12 ** Downref: Normative reference to an Informational draft: draft-ietf-rtgwg-bgp-pic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 'I-D.ietf-rtgwg-bgp-pic') == Outdated reference: A later version (-12) exists of draft-lapukhov-bgp-ecmp-considerations-04 ** Downref: Normative reference to an Informational draft: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 'I-D.lapukhov-bgp-ecmp-considerations') == Outdated reference: A later version (-02) exists of draft-lucente-grow-bmp-tlv-ebit-01 Summary: 3 errors (**), 0 flaws (~~), 40 warnings (==), 2 comments (--).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-06 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 . . . . . . . . . . . 5 72 3. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6 73 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 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 encapsulation order of the prefix, 133 in the BGP Update PDU, that the this sub TLV is describing 134 information for. 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 +----------+-----------------------------------------------------+ 196 | Value | Reason code | 197 +----------------------------------------------------------------+ 198 | [0x0001] | invalid for super network | 199 | [0x0002] | invalid for dampening | 200 | [0x0003] | invalid for damping history | 201 | [0x0004] | invalid for policy deny | 202 | [0x0005] | invalid for ROV not valid | 203 | [0x0006] | invalid for interface error | 204 | [0x0007] | invalid for nexthop route unreachable | 205 | [0x0008] | invalid for nexthop tunnel unreachable | 206 | [0x0009] | invalid for nexthop restrain | 207 | [0x000A] | invalid for not supporting BGP LSP relay | 208 | [0x000B] | invalid for being inactive within VPN insance | 209 | [0x000C] | invalid for prefix sid not exist | 210 | [0x000D] | not preferred for peer address | 211 | [0x000E] | not preferred for router ID | 212 | [0x000F] | not preferred for Cluster List | 213 | [0x0010] | not preferred for IGP cost | 214 | [0x0011] | not preferred for peer type | 215 | [0x0012] | not preferred for MED | 216 | [0x0013] | not preferred for origin | 217 | [0x0014] | not preferred for AS Path | 218 | [0x0015] | not preferred for route type | 219 | [0x0016] | not preferred for Local preference | 220 | [0x0017] | not preferred for Weight | 221 | [0x0018] | not preferred for path to next hop with bit error | 222 | [0x0019] | not preferred for path id | 223 | [0x001A] | not preferred for ROV validation | 224 | [0x001B] | not preferred for originate IP | 225 | [0x001C] | not preferred for route distinguisher | 226 | [0x001D] | not preferred for delayed route selection | 227 | [0x001E] | not preferred for imported from other instances | 228 | [0x001F] | not preferred for med plus igp cost | 229 | [0x0020] | not preferred for AIGP | 230 | [0x0021] | not preferred for BGP LSP aigp for next hop relay | 231 | [0x0022] | not preferred for nexthop IP | 232 +----------+-----------------------------------------------------+ 234 Table 2: IANA-Registered Reason Code 236 2.2. Enterprise-specific Path Status TLV 237 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 1 238 +-------------------------------+-------------------------------+ 239 |E| Type (15 bits) | Length (2 octets) | 240 +---------------------------------------------------------------+ 241 | Index (2 octets) | 242 +-------------------------------+-------------------------------+ 243 | PEN number (4 octets) | 244 +---------------------------------------------------------------+ 245 | Path Status (4 octets) | 246 +---------------------------------------------------------------+ 247 | Reason Code (2 octets, optional) | 248 +---------------------------------------------------------------+ 250 Figure 3: Encoding of Enterprise-specific Path Status TLV 252 o E bit: For an Enterprise-specific TLV, the E bit MUST be set to 1. 254 o Type = 1 (15 Bits): indicates that it's the Enterprise-specific 255 Path Status TLV. 257 o Length (2 Octets): indicates the length of the value field of the 258 Path Status TLV. The value field further consists of the Path- 259 Status field and Reason Code field. 261 o Index (2 Octets): indicates the encapsulation order of the prefix, 262 in the BGP Update PDU, that the this sub TLV is describing 263 information for. 265 o PEN Number (4 octets): indicates the IANA enterprise number IANA- 266 PEN. 268 o Path Status (4 Octets): indicates the enterprise-specific path 269 status. The format is to be determined w.r.t. each PEN number. 271 o Reason Code (2 octets, optional): indicates the reasons/ 272 explanations of the path status indicated in the Path Status 273 field. The format is to be determined w.r.t. each PEN number. 275 3. Acknowledgments 277 We would like to thank Jeff Haas for his valuable comments. 279 4. IANA Considerations 281 This document requests that IANA assign the following new parameters 282 to the BMP parameters name space. 284 Type = TBD1 (15 Bits): indicates that it is the IANA-registered Path 285 Status TLV. 287 5. Security Considerations 289 It is not believed that this document adds any additional security 290 considerations. 292 6. Normative References 294 [I-D.ietf-grow-bmp-tlv] 295 Lucente, P., Gu, Y., and H. Smit, "TLV support for BMP 296 Route Monitoring and Peer Down Messages", draft-ietf-grow- 297 bmp-tlv-03 (work in progress), September 2020. 299 [I-D.ietf-idr-best-external] 300 Marques, P., Fernando, R., Chen, E., Mohapatra, P., and H. 301 Gredler, "Advertisement of the best external route in 302 BGP", draft-ietf-idr-best-external-05 (work in progress), 303 January 2012. 305 [I-D.ietf-rtgwg-bgp-pic] 306 Bashandy, A., Filsfils, C., and P. Mohapatra, "BGP Prefix 307 Independent Convergence", draft-ietf-rtgwg-bgp-pic-12 308 (work in progress), August 2020. 310 [I-D.lapukhov-bgp-ecmp-considerations] 311 Lapukhov, P. and J. Tantsura, "Equal-Cost Multipath 312 Considerations for BGP", draft-lapukhov-bgp-ecmp- 313 considerations-04 (work in progress), May 2020. 315 [I-D.lucente-grow-bmp-tlv-ebit] 316 Lucente, P. and Y. Gu, "Support for Enterprise-specific 317 TLVs in the BGP Monitoring Protocol", draft-lucente-grow- 318 bmp-tlv-ebit-01 (work in progress), May 2020. 320 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 321 Requirement Levels", BCP 14, RFC 2119, 322 DOI 10.17487/RFC2119, March 1997, 323 . 325 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 326 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 327 DOI 10.17487/RFC4271, January 2006, 328 . 330 [RFC7854] Scudder, J., Ed., Fernando, R., and S. Stuart, "BGP 331 Monitoring Protocol (BMP)", RFC 7854, 332 DOI 10.17487/RFC7854, June 2016, 333 . 335 [RFC7911] Walton, D., Retana, A., Chen, E., and J. Scudder, 336 "Advertisement of Multiple Paths in BGP", RFC 7911, 337 DOI 10.17487/RFC7911, July 2016, 338 . 340 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 341 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 342 May 2017, . 344 Authors' Addresses 346 Camilo Cardona 347 NTT 348 164-168, Carrer de Numancia 349 Barcelona 08029 350 Spain 352 Email: camilo@ntt.net 354 Paolo Lucente 355 NTT 356 Siriusdreef 70-72 357 Hoofddorp, WT 2132 358 Netherlands 360 Email: paolo@ntt.net 362 Pierre Francois 363 INSA-Lyon 364 Lyon 365 France 367 Email: Pierre.Francois@insa-lyon.fr 368 Yunan Gu 369 Huawei 370 Huawei Bld., No.156 Beiqing Rd. 371 Beijing 100095 372 China 374 Email: guyunan@huawei.com 376 Thomas Graf 377 Swisscom 378 Binzring 17 379 Zurich 8045 380 Switzerland 382 Email: thomas.graf@swisscom.com