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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 ALTO WG J. Zhang 3 Internet-Draft Tongji University 4 Intended status: Informational K. Gao 5 Expires: 10 September 2020 Sichuan University 6 LM. Contreras 7 Telefonica 8 A. Escribano 9 Alten 10 P. Cano 11 UST Global 12 F. Cano 13 Telefonica 14 9 March 2020 16 Considerations of Deploying ALTO using BGP - Link State (BGP-LS) 17 Advertisement 18 draft-zhang-alto-bgp-ls-00 20 Abstract 22 This document discusses the requirements and deployment 23 considerations of providing Application-Layer Traffic Optimization 24 (ALTO) information in the inter-domain scenario using Border Gateway 25 Protocol - Link State (BGP-LS) extension. 27 Requirements Language 29 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 30 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 31 document are to be interpreted as described in [RFC2119]. 33 Status of This Memo 35 This Internet-Draft is submitted in full conformance with the 36 provisions of BCP 78 and BCP 79. 38 Internet-Drafts are working documents of the Internet Engineering 39 Task Force (IETF). Note that other groups may also distribute 40 working documents as Internet-Drafts. The list of current Internet- 41 Drafts is at https://datatracker.ietf.org/drafts/current/. 43 Internet-Drafts are draft documents valid for a maximum of six months 44 and may be updated, replaced, or obsoleted by other documents at any 45 time. It is inappropriate to use Internet-Drafts as reference 46 material or to cite them other than as "work in progress." 48 This Internet-Draft will expire on 10 September 2020. 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 (https://trustee.ietf.org/ 57 license-info) in effect on the date of publication of this document. 58 Please review these documents carefully, as they describe your rights 59 and restrictions with respect to this document. Code Components 60 extracted from this document must include Simplified BSD License text 61 as described in Section 4.e of the Trust Legal Provisions and are 62 provided without warranty as described in the Simplified BSD License. 64 Table of Contents 66 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 67 2. Background . . . . . . . . . . . . . . . . . . . . . . . . . 3 68 2.1. ALTO Inter-domain Deployment Problem . . . . . . . . . . 3 69 2.2. BGP-LS Background and Benefits for ALTO . . . . . . . . . 4 70 2.3. ALTO Deployment Problem using BGP-LS . . . . . . . . . . 4 71 3. Requirements for Deploying ALTO in the Inter-domain Scenario 72 using BGP-LS . . . . . . . . . . . . . . . . . . . . . . 5 73 3.1. Basic Requirements . . . . . . . . . . . . . . . . . . . 5 74 3.2. BGP-LS specific Requirements . . . . . . . . . . . . . . 6 75 4. ALTO Deployment Considerations using BGP-LS . . . . . . . . . 6 76 4.1. Provisioning of Topology Information . . . . . . . . . . 6 77 4.2. Provisioning of Routing Information . . . . . . . . . . . 6 78 4.3. Provisioning of Performance Metric Information . . . . . 7 79 5. Configuration Interfaces of Map Calculation . . . . . . . . . 7 80 5.1. Configuration Interface of Network Map Calculation . . . 7 81 5.2. Configuration Interface of Cost Map Calculation . . . . . 7 82 5.3. Configuration Examples . . . . . . . . . . . . . . . . . 8 83 6. Test Scenarios . . . . . . . . . . . . . . . . . . . . . . . 13 84 6.1. Test Environment Setup . . . . . . . . . . . . . . . . . 13 85 6.2. Test Approach . . . . . . . . . . . . . . . . . . . . . . 13 86 6.3. Test Results . . . . . . . . . . . . . . . . . . . . . . 13 87 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 88 7.1. Normative References . . . . . . . . . . . . . . . . . . 13 89 7.2. Informative References . . . . . . . . . . . . . . . . . 13 90 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14 92 1. Introduction 94 The major component of the Application-Layer Traffic Optimization 95 (ALTO) [RFC7285] deployment is the network information collection. 96 [RFC7971] discussed multiple options to collect the network 97 information from the inter-domain networks. 99 To collection the related network information for ALTO, the following 100 high-level questions should be considered: 102 * Can the ALTO service realistically discover that information? 104 * Is the distribution of that information allowed by the operators 105 of that service? 107 * Is it information that a client cannot find easily some other way? 109 The Border Gateway Protocol - Link State (BGP-LS) extension [RFC7752] 110 is one of the popular options and has been deployed in many 111 Autonomous Systems (ASes) in recent years [TODO: Need some 112 reference]. 114 BGP-LS enables ALTO server to provide underlay inter-domain topology 115 information using the link-state information in IGP domains. 117 To leverage BGP-LS to generate ALTO information effectively, some 118 requirements for deployment should be considered. 120 This document discusses these requirements and the corresponding 121 deployment considerations. 123 Additionally, this document describes some inter-domain scenarios to 124 test the deployment. 126 2. Background 128 2.1. ALTO Inter-domain Deployment Problem 130 [RFC7971] discusses considerations of ALTO deployment in different 131 network scenarios. The inter-domain network is the most common 132 scenario to deploy ALTO. 134 In practice, the following approaches are used to collect information 135 from the network: 137 * Interior Gateway Protocols (IGPs, e.g., OSPF, IS-IS): intra-domain 138 topology, link weights 140 * Border Gateway Protocol (BGP): inter-domain topology, prefixes, AS 141 numbers, AS distances, or other BGP metrics 143 * Network Management Protocols (NMPs, e.g., SNMP, Netconf): latency, 144 utilization, bandwidth 146 2.2. BGP-LS Background and Benefits for ALTO 148 BGP-LS [RFC7752] is designed to allow a BGP speaker to advertise the 149 link state database (LSDB) or traffic engineering database (TED) of 150 its connected IGP area. 152 BGP-LS defines a new address family, link state, in the BGPv4 153 framework [RFC4271]. 155 Using BGP-LS, the ALTO server can communicate to only BGP speakers to 156 collect all those information. 158 2.3. ALTO Deployment Problem using BGP-LS 160 A simple deployment solution is to connect the ALTO server as a BGP 161 reflector client of every BGP speakers in the network. However, this 162 solution is expensive and redundant. And because of the BGP updates, 163 the ALTO server could receive a lot of inconsistent redundant 164 informaiton. To avoid the redundancy and inconsistency of the 165 collected information, a deployment solution should be minimal. 167 To understand what is a minimal solution to deploy ALTO using BGP-LS, 168 the following questions are raised: 170 * Is it necessary to connect the ALTO server to every AS within a 171 BGP session? 173 * Does the session between the ALTO server and each AS have to 174 enable BGP-LS? 176 * If using BGP-LS, can the number of necessary BGP sessions be 177 reduced? 179 The following example shows a minimal deployment in a simple example 180 topology. 182 Consider the following AS-level topology as an example. Assuming all 183 the BGP sessions between ASes have enabled BGP-LS, the BGP speaker on 184 AS B can received the IGP topologies from all the three ASes. Thus, 185 to make sure the ALTO server collect all the inter-domain and intra- 186 domain topology information, the minimal deployment could be to set 187 up the the ALTO server as a BGP reflector of the BGP speaker on AS B. 189 +--------+ +--------+ +---------+ 190 | AS A |---| AS B |---| AS C | 191 +--------+ +--------+ +---------+ 192 | BGP / BGP-LS 193 | / 194 | / 195 +-------------+ 196 | ALTO Server | 197 +-------------+ 199 Figure 1: Example AS-level Topology 201 However, it is not enough for collecting the routing information. As 202 the BGP is a destination-based routing protocol, AS B could not 203 receive the routing information between endpoints from AS A and AS C. 204 To get the missing routing information, the ALTO server should also 205 connect read the BGP RIB of AS A or AS C at least. 207 As the result, the minimal solution is to establish a BGP session to 208 AS B with BGP-LS and another BGP session to AS A (or AS C) without 209 BGP-LS. 211 The following part of this document will discuss how to achieve the 212 minimal ALTO deployment using BPG-LS in detail. Specifically, two 213 questions are required to be answered: 215 * Which BGP speakers are required to be connected to the ALTO 216 server? 218 * Which BGP sessions are required to enable BGP-LS? 220 3. Requirements for Deploying ALTO in the Inter-domain Scenario using 221 BGP-LS 223 3.1. Basic Requirements 225 The following basic requirements are required by ALTO inter-domain 226 deployment in any case. 228 Req 1: The ALTO server MUST be able to collect topology information 229 from multiple IGP areas. 231 Req 2: The ALTO server MUST be able to collect routing information 232 for any pairs of endpoints. 234 Req 3: The ALTO server MUST be able to collect performance metrics 235 across routes. 237 3.2. BGP-LS specific Requirements 239 The following additional requirements are required by ALTO deployment 240 when using BGP-LS. 242 Req 4: The ALTO server SHOULD only communicate with necessary BGP 243 speakers. 245 Req 5: The ALTO server SHOULD only enable BGP-LS advertisement in 246 necessary BGP sessions between BGP speakers. 248 4. ALTO Deployment Considerations using BGP-LS 250 This section discusses some deployment considerations about how to 251 address the basic requirements (Req 1-3) when satisfying the BGP-LS 252 specific requirements (Req 4-5). 254 4.1. Provisioning of Topology Information 256 As BGP-LS advertisement cannot be propagated to remote the remote 257 ASes, each BGP speaker can only discover directly peered IGP 258 topologies using BGP-LS. 260 To satisfy Req 4, the ALTO server should only communicate to transit 261 networks or IXPs using BGP-LS. As the IGP topology of a stub network 262 can always be discovered by its peered transit networks or IXPs, so 263 it is not necessary to communicate with the stub network. 265 Specifically, the ALTO server should find a minimal BGP speaker set 266 whose peered networks can cover all IGP domains. 268 4.2. Provisioning of Routing Information 270 As BGP is a destination-based routing protocol, a stub network can 271 receive all the inter-domain routing information from all the 272 reachable destinations via BGP. 274 Thus, to satisfy Req 4, the ALTO server should only communicate to 275 stub networks using BGP, as the inter-domain routing information from 276 the transit networks is not necessary. 278 Assuming the ALTO server has already collected the complete topology 279 information using BGP-LS, the ALTO server will have the LSDB of every 280 IGP domain. 282 To satisfy Req 5, all the BGP sessions connected to the stub networks 283 do not have to enable BGP-LS. 285 4.3. Provisioning of Performance Metric Information 287 TBD. 289 5. Configuration Interfaces of Map Calculation 291 5.1. Configuration Interface of Network Map Calculation 293 rw network-map-config* [resource-id] 294 +--rw resource-id alto-types:resource-id 295 +--rw description? string 296 +--rw (params) 297 | +--:(bgp) 298 | +--rw bgp-params 299 | +--rw bgp-rib* [rib-id] 300 | +--rw rib-id rib:rib-id 301 | +--rw topology-id? topology:topology-id 302 | +--rw bgp-ls? boolean 303 +--rw (algorithm) 304 +--:(first-hop-cluster) 305 +--rw first-hop-cluster-algorithm 306 +--rw inspect-igp boolean 308 To generate a network map, one or more BGP RIBs that could provide 309 the topology information MUST specified. Each BGP RIB MAY include a 310 pre-computed topology from the RIB, and an option indicating if the 311 BPG-LS is enabled. 313 The "inspect-igp" option in the "first-hop-cluster-algorithm" field 314 indicates if the ALTO server exposes information about the IGP 315 topologies. If it is true, the ALTO server will inspect all the IGP 316 topolgies from the BGP RIBs that enalbe BGP-LS (whose "bgp-ls" option 317 is true). 319 5.2. Configuration Interface of Cost Map Calculation 320 rw cost-map-config* [resource-id] 321 +--rw resource-id alto-types:resource-id 322 +--rw description? string 323 +--rw dependent-network-map alto-types:resource-id 324 +--rw (general-params) 325 | +--:(bgp) 326 | +--rw bgp-params 327 | +--rw alternative-bgp-rib* [rib-id] 328 | +--rw rib-id rib:rib-id 329 | +--rw topology-id? topology:topology-id 330 | +--rw bgp-ls? boolean 331 +--rw cost-type* [cost-mode,cost-metric] 332 +rw cost-mode alto-types:cost-mode 333 +rw cost-metric alto-types:cost-metric 334 +rw (params)? 336 To generate a cost map, besides the dependent network map, one or 337 more alternative BGP RIBs could be specified to provide necessary 338 routing information to the ALTO server. 340 5.3. Configuration Examples 342 Example Network 344 .----------------------------. .------------. 345 | 1.1.1.0/24 6.6.6.0/24 | | 8.8.8.0/24 | 346 | | | | | | | 347 | +-+--+ +-+--+ | | +-+--+ | 348 | | R1 +--------+ R6 | | .------------. | | R8 | | 349 | +-+--+ +-+--+ | | 3.3.3.0/24 | | +-+--+ | 350 | | | | | | | | | | 351 | | +-+--+ | | +-+--+ | | +-+--+ | 352 | +-----------+ R2 +- - -|- - | -+ R3 +- - | -|- -+ R7 | | 353 | +----+ | | +++--+ | | +----+ | 354 | | | | .. | | | 355 | +-+--+ | | ..AS 200 | | AS 300 | 356 | 5.5.5.0/24------+ R5 | | `------------' `------------' 357 | +-+--+ | .. 358 | | | .. 359 | AS 100 +-+--+ | .. 360 | | R4 +- - -|- - - - +. 361 | +-+--+ | . 362 `----------------------------' . 363 . . 364 . . 365 . +--------+----+ 366 +- - - - -+ ALTO Server | 367 +-------------+ 368 Figure 2 370 * R2 - R3: BGP-LS 372 * R4 - R3: BGP-LS 374 * R7 - R3: BGP-LS 376 * R3 - ALTO: BGP-LS 378 * R4 - ALTO: BGP 380 Config a network map: 382 POST /restconf/config/alto-maps/network-map-config/bgp-networkmap 383 HOST: alto-config.example.com 384 Content-Type: application/json 385 Content-Length: TBD 387 { 388 "network-map-config": { 389 "resource-id": "bgp-networkmap", 390 "bgp-params": { 391 "bgp-rib": [ 392 { 393 "rib-id": "as200-r3", 394 "bgp-ls": true 395 } 396 ] 397 }, 398 "first-hop-cluster-algorithm": { 399 "inspect-igp": true 400 } 401 } 402 } 404 Test to fetch the network map: 406 GET /alto/networkmap/example 407 HOST: alto.example.com 409 HTTP/1.1 200 OK 410 Content-Length: TBD 411 Content-Type: application/alto-networkmap+json 413 { 414 "meta": { 415 "vtag": { 416 "resource-id": "bgp-networkmap", 417 "tag": "da65eca2eb7a10ce8b059740b0b2e3f8eb1d4785" 418 } 419 }, 420 { 421 "network-map": { 422 "PID100.R1": { 423 "ipv4": [ "1.1.1.0/24" ] 424 }, 425 "PID100.R5": { 426 "ipv4": [ "5.5.5.0/24" ] 427 }, 428 "PID100.R6": { 429 "ipv4": [ "6.6.6.0/24" ] 430 }, 431 "PID200.R3": { 432 "ipv4": [ "3.3.3.0/24" ] 433 }, 434 "PID300.R8": { 435 "ipv4": [ "8.8.8.0/24" ] 436 } 437 } 438 } 439 } 441 Config a cost map: 443 POST /restconf/config/alto-maps/cost-map-config/bgp-costmap 444 HOST: alto-config.example.com 445 Content-Type: application/json 446 Content-Length: TBD 448 { 449 "cost-map-config": { 450 "resource-id": "bgp-costmap", 451 "dependent-network-map": "bgp-networkmap", 452 "bgp-params": { 453 "alternative-bgp-rib": [ 454 { 455 "rib-id": "as100-r4", 456 "bgp-ls": false 457 } 458 ] 459 }, 460 "cost-type": [ 461 { 462 "cost-mode": "numerical", 463 "cost-metric": "hopcount" 464 } 465 ] 466 } 467 } 469 Test to fetch the cost map: 471 GET /alto/costmap/bgp-costmap 472 HOST: alto.example.com 474 HTTP/1.1 200 OK 475 Content-Length: TBD 476 Content-Type: application/alto-costmap+json 478 { 479 "meta": { 480 "vtag": { 481 "resource-id": "bgp-costmap", 482 "tag": "c0ce023b8678a7b9ec00324673b98e54656d1f6d" 483 }, 484 "dependent-vtags": [ 485 { 486 "resource-id": "bgp-networkmap", 487 "tag": "da65eca2eb7a10ce8b059740b0b2e3f8eb1d4785" 488 } 489 ], 490 "cost-type": { 491 "cost-mode": "numerical", 492 "cost-metric": "hopcount" 493 } 494 }, 495 "cost-map": { 496 "PID100.R1": { 497 "PID100.R1": 1, "PID100.R5": 3, "PID100.R6": 2, 498 "PID200.R3": 3, "PID300.R8": 5 499 }, 500 "PID100.R5": { 501 "PID100.R1": 3, "PID100.R5": 1, "PID100.R6": 3, 502 "PID200.R3": 3, "PID300.R8": 5 503 }, 504 "PID100.R6": { 505 "PID100.R1": 2, "PID100.R5": 3, "PID100.R6": 1, 506 "PID200.R3": 3, "PID300.R8": 5 507 }, 508 "PID200.R3": { 509 "PID100.R1": 3, "PID100.R5": 3, "PID100.R6": 3, 510 "PID200.R3": 1, "PID300.R8": 3 511 }, 512 "PID300.R8": { 513 "PID100.R1": 5, "PID100.R5": 5, "PID100.R6": 5, 514 "PID200.R3": 3, "PID300.R8": 1 515 } 516 } 517 } 519 6. Test Scenarios 521 6.1. Test Environment Setup 523 6.2. Test Approach 525 6.3. Test Results 527 7. References 529 7.1. Normative References 531 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 532 Requirement Levels", BCP 14, RFC 2119, 533 DOI 10.17487/RFC2119, March 1997, 534 . 536 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 537 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 538 DOI 10.17487/RFC4271, January 2006, 539 . 541 [RFC7285] Alimi, R., Ed., Penno, R., Ed., Yang, Y., Ed., Kiesel, S., 542 Previdi, S., Roome, W., Shalunov, S., and R. Woundy, 543 "Application-Layer Traffic Optimization (ALTO) Protocol", 544 RFC 7285, DOI 10.17487/RFC7285, September 2014, 545 . 547 [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and 548 S. Ray, "North-Bound Distribution of Link-State and 549 Traffic Engineering (TE) Information Using BGP", RFC 7752, 550 DOI 10.17487/RFC7752, March 2016, 551 . 553 [RFC7971] Stiemerling, M., Kiesel, S., Scharf, M., Seidel, H., and 554 S. Previdi, "Application-Layer Traffic Optimization (ALTO) 555 Deployment Considerations", RFC 7971, 556 DOI 10.17487/RFC7971, October 2016, 557 . 559 [RFC8571] Ginsberg, L., Ed., Previdi, S., Wu, Q., Tantsura, J., and 560 C. Filsfils, "BGP - Link State (BGP-LS) Advertisement of 561 IGP Traffic Engineering Performance Metric Extensions", 562 RFC 8571, DOI 10.17487/RFC8571, March 2019, 563 . 565 7.2. Informative References 567 [I-D.ietf-alto-cost-calendar] 568 Randriamasy, S., Yang, Y., WU, Q., Lingli, D., and N. 569 Schwan, "Application-Layer Traffic Optimization (ALTO) 570 Cost Calendar", Work in Progress, Internet-Draft, draft- 571 ietf-alto-cost-calendar-19, 2 March 2020, 572 . 575 [I-D.ietf-alto-incr-update-sse] 576 Roome, W. and Y. Yang, "ALTO Incremental Updates Using 577 Server-Sent Events (SSE)", Work in Progress, Internet- 578 Draft, draft-ietf-alto-incr-update-sse-20, 20 February 579 2020, . 582 [I-D.ietf-alto-path-vector] 583 Gao, K., Lee, Y., Randriamasy, S., Yang, Y., and J. Zhang, 584 "ALTO Extension: Path Vector", Work in Progress, Internet- 585 Draft, draft-ietf-alto-path-vector-09, 3 November 2019, 586 . 589 [I-D.ietf-alto-unified-props-new] 590 Roome, W., Randriamasy, S., Yang, Y., Zhang, J., and K. 591 Gao, "Unified Properties for the ALTO Protocol", Work in 592 Progress, Internet-Draft, draft-ietf-alto-unified-props- 593 new-10, 4 November 2019, . 596 [I-D.wang-idr-bgpls-inter-as-topology-ext] 597 Wang, A. and H. Chen, "BGP-LS Extension for Inter-AS 598 Topology Retrieval", Work in Progress, Internet-Draft, 599 draft-wang-idr-bgpls-inter-as-topology-ext-02, 13 August 600 2018, . 603 [RFC8189] Randriamasy, S., Roome, W., and N. Schwan, "Multi-Cost 604 Application-Layer Traffic Optimization (ALTO)", RFC 8189, 605 DOI 10.17487/RFC8189, October 2017, 606 . 608 Authors' Addresses 610 Jingxuan Jensen Zhang 611 Tongji University 612 4800 Cao'An Hwy 613 Shanghai 614 201804 615 China 617 Email: jingxuan.zhang@tongji.edu.cn 619 Kai Gao 620 Sichuan University 621 No.24 South Section 1, Yihuan Road 622 Chengdu 623 610000 624 China 626 Email: kaigao@scu.edu.cn 628 Luis M. Contreras 629 Telefonica 630 Ronda de la Comunicacion, s/n 631 28050 Madrid 632 Spain 634 Email: luismiguel.contrerasmurillo@telefonica.com 636 Anais Escribano 637 Alten 638 Carrer de Josep Pla, 2 639 08019 Barcelona 640 Spain 642 Email: anais.escribano@alten.es 644 Patricia Cano 645 UST Global 646 Ramirez de Arellano 29 647 28043 Madrid 648 Spain 650 Email: Patricia.Diez@ust-global.com 652 Francisco Cano 653 Telefonica 654 Avenida del Conocimiento, 12 655 18016 Granada 656 Spain 657 Email: franciscojose.canohila@telefonica.com