idnits 2.17.00 (12 Aug 2021) /tmp/idnits54768/draft-schott-alto-new-transport-00.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- ** The abstract seems to contain references ([RFC7285], [RFC8895]), which it shouldn't. Please replace those with straight textual mentions of the documents in question. Miscellaneous warnings: ---------------------------------------------------------------------------- == Line 201 has weird spacing: '...NString tag;]...' -- The document date (March 5, 2022) is 70 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Missing Reference: 'RFC 8895' is mentioned on line 196, but not defined == Unused Reference: 'RFC7540' is defined on line 563, but no explicit reference was found in the text == Unused Reference: 'RFC7971' is defined on line 579, but no explicit reference was found in the text Summary: 1 error (**), 0 flaws (~~), 4 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 ALTO Working Group R. Schott 3 Internet-Draft Deutsche Telekom 4 Intended status: Standards Track Y. Yang 5 Expires: September 6, 2022 Yale University 6 K. Gao 7 Sichuan University 8 J. Zhang 9 Tongji University 10 March 5, 2022 12 ALTO New Transport using HTTP/2 13 draft-schott-alto-new-transport-00 15 Abstract 17 The ALTO base protocol [RFC7285] uses HTTP/1.x as the transport 18 protocol and hence ALTO transport includes the limitations of 19 HTTP/1.x. ALTO/SSE [RFC8895] addresses some of the limitations, but 20 is still based on HTTP/1.x. This document introduces ALTO new 21 transport, which provides the transport functions of ALTO/SSE on top 22 of HTTP/2, for more efficient ALTO transport. 24 Requirements Language 26 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 27 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 28 "OPTIONAL" in this document are to be interpreted as described in BCP 29 14 [RFC2119][RFC8174] when, and only when, they appear in all 30 capitals, as shown here. 32 Status of This Memo 34 This Internet-Draft is submitted in full conformance with the 35 provisions of BCP 78 and BCP 79. 37 Internet-Drafts are working documents of the Internet Engineering 38 Task Force (IETF). Note that other groups may also distribute 39 working documents as Internet-Drafts. The list of current Internet- 40 Drafts is at http://datatracker.ietf.org/drafts/current/. 42 Internet-Drafts are draft documents valid for a maximum of six months 43 and may be updated, replaced, or obsoleted by other documents at any 44 time. It is inappropriate to use Internet-Drafts as reference 45 material or to cite them other than as "work in progress." 47 This Internet-Draft will expire on September 6, 2022. 49 Copyright Notice 51 Copyright (c) 2022 IETF Trust and the persons identified as the 52 document authors. All rights reserved. 54 This document is subject to BCP 78 and the IETF Trust's Legal 55 Provisions Relating to IETF Documents 56 (http://trustee.ietf.org/license-info) in effect on the date of 57 publication of this document. Please review these documents 58 carefully, as they describe your rights and restrictions with respect 59 to this document. Code Components extracted from this document must 60 include Simplified BSD License text as described in Section 4.e of 61 the Trust Legal Provisions and are provided without warranty as 62 described in the Simplified BSD License. 64 Table of Contents 66 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 67 2. ALTO New Transport Design Requirements . . . . . . . . . . . 3 68 3. ALTO New Transport Information Structure . . . . . . . . . . 4 69 3.1. Transport Queue . . . . . . . . . . . . . . . . . . . . . 5 70 3.2. Incremental Update Message Queue . . . . . . . . . . . . 5 71 3.3. Examples . . . . . . . . . . . . . . . . . . . . . . . . 5 72 4. ALTO/H2 Information Resource Directory (IRD) . . . . . . . . 10 73 5. Security Considerations . . . . . . . . . . . . . . . . . . . 13 74 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 75 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 14 76 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 77 8.1. Normative References . . . . . . . . . . . . . . . . . . 14 78 8.2. Informative References . . . . . . . . . . . . . . . . . 14 79 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15 81 1. Introduction 83 Application-Layer Traffic Optimization (ALTO) provides a means for 84 network applications to obtain network status information. The ALTO 85 base protocol [RFC7285] is based on the sequential request and 86 response model of HTTP/1.1 [RFC7230]; hence, in the base protocol, an 87 ALTO client can issue only a sequence of requests on network 88 information resources, and the ALTO server sends the information 89 resources one-by-one, in the order of the request sequence. 91 To address the use cases where an ALTO client may need to efficiently 92 monitor changes to a set of network information resources and the 93 protocol is still based on the HTTP/1.1 model, the ALTO Working Group 94 introduces ALTO/SSE (ALTO Incremental Update based on Server-Sent- 95 Event) [RFC8895], so that an ALTO client can manage (i.e., add and 96 remove) a set of requests maintained at an ALTO server, and the 97 server can continuously, concurrently, and incrementally push updates 98 whenever a monitored network information resource changes. Figure 1 99 shows the architecture and message flow of ALTO/SSE, which can be 100 considered as a more general transport protocol than the ALTO base 101 transport protocol. Although ALTO/SSE allows the concurrent 102 transport of multiple ALTO information resources, it has complexities 103 and limitations. For example, it requires that the server provide a 104 separate control URI, leading to complexity in management. 106 ------------------------------------------------------------------ 107 | | 108 | +-------+ +-------+ 1. init request +------+ | 109 | | | | | <------------- | | | 110 | | | | | -------------> | | | 111 | 3.add/ | | | | 1'. control uri | | | 112 | remove | | | | | | | 113 | resource |Stream | |Update | | | | 114 -------->|Control| private |Stream | 2a. data update |Client| -- 115 |Server |<------->|Server | messages | | 116 -------- | | | | --------------> | | <- 117 | response | | | | --------------> | | | 118 | | | | | 2b.control update| | | 119 | +-------+ +-------+ messages +------+ | 120 | | 121 ------------------------------------------------------------------ 123 Figure 1: ALTO SSE Architecture and Message Flow. 125 This document specifies ALTO new transport, which realizes ALTO/SSE 126 but takes advantage of new HTTP capabilities. 128 2. ALTO New Transport Design Requirements 130 The new transport is designed to satisfy a set of requirements. 131 First, it should satisfy the following requirements to realize the 132 functions of ALTO/SSE: 134 o R0: Client can request any resource using the connection, just as 135 using ALTO base protocol using HTTP/1.x. 137 o R1: The client can request the addition (start) of incremental 138 updates to a resource. 140 o R2: The client can request the deletion (stop) of incremental 141 updates to a resource. 143 o R3: The server can signal to the client the start or stop of 144 incremental updates to a resource. 146 o R4: The server can choose the type of each incremental update 147 endcoding, as long as the type is indicated to be acceptable by 148 the client. 150 Following the ALTO framework, the new transport protocol should still 151 be HTTP based: 153 o R5: The design follows basic principle of HTTP---Representational 154 State Transfer and hence can use only HTTP verbs (GET, POST, PUT, 155 DELETE, HEAD). 157 o R6: The design takes advantage of HTTP/2 design features such as 158 parallel transfer and respects HTTP/2 semantics such as the 159 semantics of PUSH_PROMISE. 161 To allow flexible deployment, the new transport protocol should be 162 flexible: 164 o R7: The design should support capability negotiation. 166 3. ALTO New Transport Information Structure 168 A key design of ALTO new transport is to distinguish between 169 information about ALTO resources and information about ALTO 170 transport. It introduces the following transport information 171 structures to distribute ALTO information resources: 173 o The transport state from the ALTO server to an ALTO client (or a 174 set of clients) for an ALTO information resource is conceptually 175 through a transport queue. A static ALTO information resource 176 (e.g., Cost Map, Network Map) has a single transport queue, and a 177 dynamic ALTO information resource (e.g., Filtered Cost Map) may 178 create a queue for each unique filter request. 180 o Each transport queue maintains two states: (1) the incremental 181 update message queue TQ-BASE-URI/m, and (2) the recipients set TQ- 182 BASE-URI/r, where TQ-BASE-URI is the base URI pointing to the 183 transport queue, TQ-BASE-URI/m/meta is the list of update messages 184 in the update message queue, and TQ-BASE-URI/m/msg-seq-no is a 185 specific update. A transport queue can be created by a POST URI; 186 a client can delete a transport queue by sending DELETE the TQ- 187 BASE-URI. A client with an interest to receive incremental 188 updates should be in TQ-BASE-URI/r. 190 o The transport queue state is exposed to clients through views; 191 that is, a client can see only a virtual view of the server state. 193 3.1. Transport Queue 195 An ALTO client creates a transport queue using ALTO SSE AddUpdateReq 196 ([RFC 8895] Sec. 6.5). Unless the request has incremental-changes to 197 be false, the client is added to TQ-BASE-URI/r. 199 object { 200 ResourceID resource-id; 201 [JSONString tag;] 202 [Boolean incremental-changes;] 203 [Object input;] 204 } AddUpdateReq; 206 Any disconnection between the client and the server will remove the 207 client from the receiver queue; that is, the receiver state is 208 ephemeral. A client can also remove itself by deleting itself from 209 the receiver set. 211 3.2. Incremental Update Message Queue 213 When a client joins a transport queue and specifies incremental push 214 updates, the first message pushed from the server to the client is 215 the last independent message in the incremental message queue, unless 216 the client specifies a matching message tag. 218 3.3. Examples 220 The first example is client receiving cost map and its updates. 222 POST /tqs HTTP/2 223 Host: alto.example.com 224 Accept: application/alto-transport+json 225 Content-Type: application/alto-updatestreamparams+json 226 Content-Length: TBD 228 { 229 "resource-id": "my-routingcost-map" 230 } 232 HTTP/2 200 OK 233 Content-Type: application/alto-transport+json 235 {"mq": "/updates/streams/2718281828459"} 237 Note that the example above uses HTTP/1.x notation, and it is 238 straightforward to change to use HTTP/2 notation. We use the short 239 notation for now and will update to the HTTP/2 notation in later 240 revisions. 242 Client -> server request 244 HEADERS 245 - END_STREAM 246 - END_HEADERS 247 :method = POST 248 :scheme = https 249 :path = /tqs 251 CONTINUATION 252 + END_HEADERS 253 host = alto.example.com 254 accept = application/alto-transport+json 255 content-type = application/alto-updatestreamparams+json 256 content-length = TBD 258 DATA 259 + END_STREAM 260 { 261 "resource-id": "my-routingcost-map" 262 } 264 Server -> client response: 266 HEADERS 267 - END_STREAM 268 + END_HEADERS 269 :status = 200 270 content-type = application/alto-transport+json 271 content-length = TBD 273 DATA 274 + END_STREAM 275 {"mq": "/updates/streams/2718281828459"} 277 The client can check the status of the transport queue from the same 278 connection: 280 GET /updates/streams/2718281828459/m/meta HTTP/2 281 Accept: application/alto-transport+json 283 HTTP/2 200 OK 284 Content-Type: application/alto-transport+json 286 { 287 [ 288 {"seq": 101, 289 "media-type": "application/alto-costmap+json", 290 "tag": "a10ce8b059740b0b2e3f8eb1d4785acd42231bfe" }, 291 {"seq": 102, 292 "media-type": "application/merge-patch+json", 293 "tag": "cdf0222x59740b0b2e3f8eb1d4785acd42231bfe" }, 294 {"seq": 103, 295 "media-type": "application/merge-patch+json", 296 "tag": "8eb1d4785acd42231bfecdf0222x59740b0b2e3f", 297 "equi-link": "/updates/streams/2718281828459/m/aliase1"} 299 ] 300 } 302 The client can directly request an element in the queue, for example, 303 GET /updates/streams/2718281828459/m/101 HTTP/2 304 Accept: application/application/alto-costmap+json 306 HTTP/2 200 OK 307 Content-Type: application/alto-costmap+json 309 { 310 "meta" : { 311 "dependent-vtags" : [{ 312 "resource-id": "my-network-map", 313 "tag": "da65eca2eb7a10ce8b059740b0b2e3f8eb1d4785" 314 }], 315 "cost-type" : { 316 "cost-mode" : "numerical", 317 "cost-metric": "routingcost" 318 }, 319 "vtag": { 320 "resource-id" : "my-routingcost-map", 321 "tag" : "3ee2cb7e8d63d9fab71b9b34cbf764436315542e" 322 } 323 }, 324 "cost-map" : { 325 "PID1": { "PID1": 1, "PID2": 5, "PID3": 10 }, 326 "PID2": { "PID1": 5, "PID2": 1, "PID3": 15 }, 327 "PID3": { "PID1": 20, "PID2": 15 } 328 } 329 } 331 Note from the transport queue state that the 103 message has an 332 OPTIONAL link to a complete snapshot, which a client can request. 334 Instead of directly requesting, the client can wait for the server 335 for incremental push, where the server first sends PUSH_PROMISE with 336 the GET URI as above. 338 A client can leave incremental updates by sending the request: 340 DELETE /updates/streams/2718281828459/r/self HTTP/2 341 Accept: application/alto-transport+json 343 HTTP/2 200 OK 345 A second client can can request the creation for the same resource 346 and the server can return the same transport queue. 348 A client can delete the transport queue from its view, and as long as 349 there are other clients, the server will still maintain the transport 350 queue. 352 DELETE /updates/streams/2718281828459 HTTP/2 353 Accept: application/alto-transport+json 355 HTTP/2 200 OK 357 The transport queue is not limited to only GET resources. The client 358 can also request a filtered ALTO resource, which is shown in the 359 example below: 361 POST /tqs HTTP/2 362 Host: alto.example.com 363 Accept: application/alto-transport+json 364 Content-Type: application/alto-updatestreamparams+json 365 Content-Length: 382 367 { 368 "resource-id": "my-pv", 369 "input": { 370 "cost-type": { 371 "cost-mode": "array", 372 "cost-metric": "ane-path" 373 }, 374 "endpoints": { 375 "srcs": [ "ipv4:192.0.2.2" ], 376 "dsts": [ "ipv4:192.0.2.89", "ipv4:203.0.113.45" ] 377 }, 378 "ane-properties": [ "maxresbw", "persistent-entities" ] 379 } 380 } 382 HTTP/2 200 OK 383 Content-Type: application/alto-transport+json 385 {"mq": "/updates/streams/2718281828459"} 387 4. ALTO/H2 Information Resource Directory (IRD) 389 Extending the IRD example in Section 8.1 of [RFC8895], Figure 2 is 390 the IRD of an ALTO server supporting ALTO base protocol, ALTO/SSE, 391 and ALTO/H2. 393 In particular, 394 "my-network-map": { 395 "uri": "https://alto.example.com/networkmap", 396 "media-type": "application/alto-networkmap+json", 397 }, 398 "my-routingcost-map": { 399 "uri": "https://alto.example.com/costmap/routingcost", 400 "media-type": "application/alto-costmap+json", 401 "uses": ["my-networkmap"], 402 "capabilities": { 403 "cost-type-names": ["num-routingcost"] 404 } 405 }, 406 "my-hopcount-map": { 407 "uri": "https://alto.example.com/costmap/hopcount", 408 "media-type": "application/alto-costmap+json", 409 "uses": ["my-networkmap"], 410 "capabilities": { 411 "cost-type-names": ["num-hopcount"] 412 } 413 }, 414 "my-filtered-cost-map": { 415 "uri": "https://alto.example.com/costmap/filtered/constraints", 416 "media-type": "application/alto-costmap+json", 417 "accepts": "application/alto-costmapfilter+json", 418 "uses": ["my-networkmap"], 419 "capabilities": { 420 "cost-type-names": ["num-routingcost", "num-hopcount"], 421 "cost-constraints": true 422 } 423 }, 424 "my-simple-filtered-cost-map": { 425 "uri": "https://alto.example.com/costmap/filtered/simple", 426 "media-type": "application/alto-costmap+json", 427 "accepts": "application/alto-costmapfilter+json", 428 "uses": ["my-networkmap"], 429 "capabilities": { 430 "cost-type-names": ["num-routingcost", "num-hopcount"], 431 "cost-constraints": false 432 } 433 }, 434 "my-props": { 435 "uri": "https://alto.example.com/properties", 436 "media-type": "application/alto-endpointprops+json", 437 "accepts": "application/alto-endpointpropparams+json", 438 "capabilities": { 439 "prop-types": ["priv:ietf-bandwidth"] 440 } 441 }, 442 "my-pv": { 443 "uri": "https://alto.example.com/endpointcost/pv", 444 "media-type": "multipart/related; 445 type=application/alto-endpointcost+json", 446 "accepts": "application/alto-endpointcostparams+json", 447 "capabilities": { 448 "cost-type-names": [ "path-vector" ], 449 "ane-properties": [ "maxresbw", "persistent-entities" ] 450 } 451 }, 452 "update-my-costs": { 453 "uri": "https://alto.example.com/updates/costs", 454 "media-type": "text/event-stream", 455 "accepts": "application/alto-updatestreamparams+json", 456 "uses": [ 457 "my-network-map", 458 "my-routingcost-map", 459 "my-hopcount-map", 460 "my-simple-filtered-cost-map" 461 ], 462 "capabilities": { 463 "incremental-change-media-types": { 464 "my-network-map": "application/json-patch+json", 465 "my-routingcost-map": "application/merge-patch+json", 466 "my-hopcount-map": "application/merge-patch+json" 467 }, 468 "support-stream-control": true 469 } 470 }, 471 "update-my-costs-h2": { 472 "uri": "https://alto.example.com/updates-h2/costs", 473 "media-type": "application/alto-h2", 474 "accepts": "application/alto-updatestreamparams+json", 475 "uses": [ 476 "my-network-map", 477 "my-routingcost-map", 478 "my-hopcount-map", 479 "my-simple-filtered-cost-map" 480 ], 481 "capabilities": { 482 "incremental-change-media-types": { 483 "my-network-map": "application/json-patch+json", 484 "my-routingcost-map": "application/merge-patch+json", 485 "my-hopcount-map": "application/merge-patch+json" 486 }, 487 "support-stream-control": true 488 } 489 }, 490 "update-my-props": { 491 "uri": "https://alto.example.com/updates/properties", 492 "media-type": "text/event-stream", 493 "uses": [ "my-props" ], 494 "accepts": "application/alto-updatestreamparams+json", 495 "capabilities": { 496 "incremental-change-media-types": { 497 "my-props": "application/merge-patch+json" 498 }, 499 "support-stream-control": true 500 } 501 }, 502 "update-my-pv": { 503 "uri": "https://alto.example.com/updates/pv", 504 "media-type": "text/event-stream", 505 "uses": [ "my-pv" ], 506 "accepts": "application/alto-updatestreamparams+json", 507 "capabilities": { 508 "incremental-change-media-types": { 509 "my-pv": "application/merge-patch+json" 510 }, 511 "support-stream-control": true 512 } 513 } 515 Note that it is straightforward for an ALTO sever to run HTTP/2 and 516 support concurrent retrieval of multiple resources such as "my- 517 network-map" and "my-routingcost-map" using multiple HTTP/2 streams 518 with the need to introducing ALTO/H2. 520 The resource "update-my-costs-h2" provides an ALTO/H2 based 521 connection, and this is indicated by the media-type "application/ 522 alto-h2". For an ALTO/H2 connection, the client can send in a 523 sequence of control requests using media type application/alto- 524 updatestreamparams+json. The server creates HTTP/2 streams and 525 pushes updates to the client. 527 5. Security Considerations 529 The properties defined in this document present no security 530 considerations beyond those in Section 15 of the base ALTO 531 specification [RFC7285]. 533 6. IANA Considerations 535 IANA will need to register the alto-h2 media type under ALTO registry 536 as defined in [RFC7285]. 538 7. Acknowledgments 540 The authors of this document would also like to thank many for the 541 reviews and comments. 543 8. References 545 8.1. Normative References 547 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 548 Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/ 549 RFC2119, March 1997, . 552 [RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer 553 Protocol (HTTP/1.1): Message Syntax and Routing", RFC 554 7230, DOI 10.17487/RFC7230, June 2014, . 557 [RFC7285] Alimi, R., Ed., Penno, R., Ed., Yang, Y., Ed., Kiesel, S., 558 Previdi, S., Roome, W., Shalunov, S., and R. Woundy, 559 "Application-Layer Traffic Optimization (ALTO) Protocol", 560 RFC 7285, DOI 10.17487/RFC7285, September 2014, 561 . 563 [RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext 564 Transfer Protocol Version 2 (HTTP/2)", RFC 7540, DOI 565 10.17487/RFC7540, May 2015, . 568 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 569 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 570 May 2017, . 572 [RFC8895] Roome, W. and Y. Yang, "Application-Layer Traffic 573 Optimization (ALTO) Incremental Updates Using Server-Sent 574 Events (SSE)", RFC 8895, DOI 10.17487/RFC8895, November 575 2020, . 577 8.2. Informative References 579 [RFC7971] Stiemerling, M., Kiesel, S., Scharf, M., Seidel, H., and 580 S. Previdi, "Application-Layer Traffic Optimization (ALTO) 581 Deployment Considerations", RFC 7971, DOI 10.17487/ 582 RFC7971, October 2016, . 585 Authors' Addresses 587 Roland Schott 588 Deutsche Telekom 589 Heinrich-Hertz-Strasse 3-7 590 64295 Darmstadt 591 Germany 593 Email: Roland.Schott@telekom.de 595 Y. Richard Yang 596 Yale University 597 51 Prospect St 598 New Haven, CT 06520 599 USA 601 Email: yry@cs.yale.edu 603 Kai Gao 604 Sichuan University 605 Chengdu 201804 606 China 608 Email: kgao@scu.edu.cn 610 Jingxuan Jensen Zhang 611 Tongji University 612 4800 Cao'An Hwy 613 Shanghai 201804 614 China 616 Email: jingxuan.n.zhang@gmail.com