idnits 2.17.1 draft-ietf-alto-cost-calendar-05.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 : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (June 22, 2018) is 2134 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: 'TODO' is mentioned on line 972, but not defined Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group S. Randriamasy 3 Internet-Draft Nokia Bell Labs 4 Intended status: Standards Track R. Yang 5 Expires: December 24, 2018 Yale University 6 Q. Wu 7 Huawei 8 L. Deng 9 China Mobile 10 N. Schwan 11 Thales Deutschland 12 June 22, 2018 14 ALTO Cost Calendar 15 draft-ietf-alto-cost-calendar-05 17 Abstract 19 The goal of Application-Layer Traffic Optimization (ALTO) is to 20 bridge the gap between network and applications by provisioning 21 network related information in order to allow applications to make 22 network informed decisions. The present draft extends the ALTO cost 23 information so as to broaden the decision possibilities of 24 applications to not only decide 'where' to connect to, but also 25 'when'. This is useful to applications that need to schedule their 26 data transfers and connections and have a degree of freedom to do so. 27 ALTO guidance to schedule application traffic can also efficiently 28 help for load balancing and resources efficiency. Besides, the ALTO 29 Cost Calendar allows to schedule the ALTO requests themselves and 30 thus to save a number of ALTO transactions. 32 This draft proposes new capabilities and attributes on filtered cost 33 maps and endpoint cost maps enabling an ALTO Server to provide "Cost 34 Calendars". These capabilities are applicable to ALTO metrics with 35 time-varying values. With ALTO Cost Calendars, an ALTO Server 36 exposes ALTO cost values in JSON arrays where each value corresponds 37 to a given time interval. The time intervals as well as other 38 Calendar attributes are specified in the IRD and ALTO Server 39 responses. 41 Requirements Language 43 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 44 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 45 document are to be interpreted as described in RFC 2119 [RFC2119]. 47 Status of This Memo 49 This Internet-Draft is submitted in full conformance with the 50 provisions of BCP 78 and BCP 79. 52 Internet-Drafts are working documents of the Internet Engineering 53 Task Force (IETF). Note that other groups may also distribute 54 working documents as Internet-Drafts. The list of current Internet- 55 Drafts is at https://datatracker.ietf.org/drafts/current/. 57 Internet-Drafts are draft documents valid for a maximum of six months 58 and may be updated, replaced, or obsoleted by other documents at any 59 time. It is inappropriate to use Internet-Drafts as reference 60 material or to cite them other than as "work in progress." 62 This Internet-Draft will expire on December 24, 2018. 64 Copyright Notice 66 Copyright (c) 2018 IETF Trust and the persons identified as the 67 document authors. All rights reserved. 69 This document is subject to BCP 78 and the IETF Trust's Legal 70 Provisions Relating to IETF Documents 71 (https://trustee.ietf.org/license-info) in effect on the date of 72 publication of this document. Please review these documents 73 carefully, as they describe your rights and restrictions with respect 74 to this document. Code Components extracted from this document must 75 include Simplified BSD License text as described in Section 4.e of 76 the Trust Legal Provisions and are provided without warranty as 77 described in the Simplified BSD License. 79 Table of Contents 81 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 82 2. Overview of ALTO Cost Calendars . . . . . . . . . . . . . . . 4 83 2.1. ALTO Cost Calendar information features . . . . . . . . . 5 84 2.2. ALTO Calendar design characteristics . . . . . . . . . . 6 85 2.2.1. ALTO Cost Calendar for all cost modes . . . . . . . . 6 86 2.2.2. Compatibility with legacy ALTO Clients . . . . . . . 7 87 3. ALTO Calendar specification: IRD extensions . . . . . . . . . 7 88 3.1. Calendar attributes in the IRD resources capabilities . . 7 89 3.2. Calendars in a delegate IRD . . . . . . . . . . . . . . . 9 90 3.3. Example IRD with ALTO Cost Calendars . . . . . . . . . . 9 91 4. ALTO Calendar specification: Service Information Resources . 12 92 4.1. Calendar extensions for filtered cost maps . . . . . . . 13 93 4.1.1. Calendar extensions in Filtered Cost Map requests . . 13 94 4.1.2. Calendar extensions in Filtered Cost Map responses . 14 95 4.1.3. Use case and example: FCM with a bandwidth Calendar . 16 96 4.2. Calendar extensions in the Endpoint Cost Service . . . . 18 97 4.2.1. Calendar specific input in Endpoint Cost requests . 18 98 4.2.2. Calendar attributes in the Endpoint Cost response . . 18 99 4.2.3. Use case and example: ECS with a routingcost Calendar 19 100 4.2.4. Use case and example: ECS with a multi-cost calendar 101 for routingcost and latency . . . . . . . . . . . . . 22 102 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24 103 6. Security Considerations . . . . . . . . . . . . . . . . . . . 24 104 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 24 105 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 24 106 8.1. Normative References . . . . . . . . . . . . . . . . . . 24 107 8.2. Informative References . . . . . . . . . . . . . . . . . 24 108 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 25 110 1. Introduction 112 IETF is currently standardizing the ALTO protocol which aims at 113 providing guidance to overlay applications needing to select one or 114 several hosts from a set of candidates able to provide a desired 115 resource. This guidance is based on parameters that affect 116 performance and efficiency of the data transmission between the hosts 117 such as the topological distance. The goal of ALTO is to improve the 118 Quality of Experience (QoE) in the application while optimizing 119 resource usage in the underlying network infrastructure. 121 The ALTO protocol in [RFC7285] specifies a network map which defines 122 groupings of endpoints in provider-defined network regions (called 123 PIDs). The Cost Map Service, Endpoint Cost Service (ECS) and 124 Endpoint Ranking Service then provide ISP-defined costs and rankings 125 for connections among the specified endpoints and PIDs and thus 126 incentives for application clients to connect to ISP preferred 127 locations, e.g. to reduce their costs. ALTO intentionally avoids 128 provisioning realtime information as explained in the ALTO Problem 129 Statement [RFC5693] and ALTO Requirements [RFC5693].Thus the current 130 Cost Map and Endpoint Cost Service are providing, for a given Cost 131 Type, exactly one path cost value. Applications have to query one of 132 these two services to retrieve the currently valid cost values. They 133 therefore need to plan their ALTO information requests according to 134 their own estimation of the frequency of cost value change. 136 With [RFC7285], an ALTO client should interpret the returned costs as 137 those at the query moment. However, Network costs can fluctuate, 138 e.g. due to diurnal patterns of traffic demand or planned events such 139 as network maintenance, holidays or highly publicized events. 140 Providing network costs for only the current time thus may not be 141 sufficient, in particular for applications that can schedule their 142 traffic in a span of time, for example by deferring backup to night 143 during traffic trough. 145 In case the ALTO Cost value changes are predictable over a certain 146 period of time and the application does not require immediate data 147 transfer, it can save time to get the whole set of cost values over 148 this period in one single ALTO response. Using this set to schedule 149 data transfers allows optimizing the network resources usage and QoE. 150 ALTO Clients and Servers can also minimize their workload by reducing 151 and accordingly scheduling their data exchanges. 153 This document extends RFC7285 to allow an ALTO server to provide 154 network costs for a given duration of time. A sequence of network 155 costs across a time span for a given pair of network locations is 156 named an "ALTO Cost Calendar". The Filtered Cost Map Service and 157 Endpoint Cost Service are extended to provide Cost Calendars. In 158 addition to this functional ALTO enhancement, we expect to further 159 gain on storage and on the wire data exchange by gathering multiple 160 Cost Values for one Cost Type into one single ALTO Server response. 162 In this draft an "ALTO Cost Calendar" is specified by information 163 resources capabilities that are applicable to time-sensitive ALTO 164 metrics. An ALTO Cost Calendar exposes ALTO Cost Values in JSON 165 arrays where each value corresponds to a given time interval. The 166 time intervals as well as other Calendar attributes are specified in 167 the IRD and in the Server response to allow the ALTO Client to 168 interpret the received ALTO values. Last, the proposed extensions 169 for ALTO Calendars are applicable to any Cost Mode and they ensure 170 backwards compatibility with legacy ALTO clients. 172 In the rest of this document, Section 2 provides the design 173 characteristics. Sections 3 and 4 define the formal specifications 174 for the IRD and the information resources. Section 5 provides non- 175 normative use cases to illustrate the usage of cost calendars. IANA 176 considerations and security considerations will be completed in 177 further versions. 179 2. Overview of ALTO Cost Calendars 181 An ALTO Cost calendar provided by the ALTO Server provides 2 182 information items: 184 o an array of values for a given metric, where each value 185 corresponds to a time interval, where the value array can 186 sometimes be a cyclic pattern that repeats a certain number of 187 times. 189 o attributes describing the time scope of the calendar such as the 190 size and number of the intervals and the date of the starting 191 point of the calendar, allowing an ALTO Client to properly 192 interpret the values. 194 An ALTO Cost Calendar can be used like a "time table" to figure out 195 the best time to schedule data transfers and also to proactively 196 manage application traffic given predictable events such as flash 197 crowds, traffic intensive holidays and network maintenance. It may 198 be viewed as a synthetic abstraction of real measurements that can be 199 historic or be a prediction for upcoming time periods. 201 Most likely, the ALTO Cost Calendar would be used for the Endpoint 202 Cost Service, assuming that a limited set of feasible Endpoints for a 203 non-real time application is already identified, that they do not 204 need to be accessed immediately and that their access can be 205 scheduled within a given time period. The Filtered Cost Map Service 206 is also applicable as long as the size of the Map allows it. 208 2.1. ALTO Cost Calendar information features 210 The Calendar attributes are provided in the IRD and in ALTO Server 211 responses. The IRD announces attributes with dateless values in its 212 information resources capabilities, where as attributes with time 213 dependent values are provided in the "meta" of Server responses. The 214 ALTO Cost Calendar attributes provide the following information: 216 o attributes to interpret the time scope of the Calendar value 217 array: 219 * generic time zone, 221 * applicable time interval size for each calendar value: 222 combining a number and a time unit to reflect for example: 1 223 hour, 2 minutes, 10 seconds, 1 week, 1 month, 225 * duration of the Calendar: e.g. the number of intervals provided 226 in the calendar. 228 o "calendar-start-date": specifying when the calendar starts, that 229 is to which date the first value of the cost calendar is 230 applicable. 232 o "repeated": an optional attribute indicating for how many 233 iterations the provided calendar will have the same values. The 234 server may use it to allow the client to schedule its next request 235 and thus save its own workload by avoiding to process useless 236 requests. 238 2.2. ALTO Calendar design characteristics 240 The protocol extension placeholders for an ALTO Calendar are: the 241 IRD, the ALTO requests and responses for Cost calendars. 243 Extensions are designed to be light and ensure backwards 244 compatibility with base protocol ALTO Clients and with other 245 extensions. It uses section 8.3.7 "Parsing of Unknown Fields" of 246 RFC7285 that writes: "Extensions may include additional fields within 247 JSON objects defined in this document. ALTO implementations MUST 248 ignore unknown fields when processing ALTO messages." 250 The calendar-specific capabilities are integrated in the information 251 resources of the IRD and in the "meta" member of ALTO responses to 252 Cost Calendars requests. A calendar and its capabilities are 253 associated with a given information resource and within this 254 information resource with a given cost type. This design has several 255 advantages: 257 o it does not introduce a new mode, 259 o it does not introduce new media types, 261 o it allows an ALTO Server to offer calendar capabilities on a cost 262 type, with attributes values adapted to each information resource. 264 The Applicable Calendared information resources are: 266 o the Filtered Cost Map, 268 o the Endpoint Cost Map. 270 The ALTO Server can choose in which frequency it provides cost 271 Calendars to ALTO Clients. It may either provide calendar updates 272 starting at the request date, or carefully schedule its updates so as 273 to take profit from a potential repetition/periodicity of calendar 274 values. 276 2.2.1. ALTO Cost Calendar for all cost modes 278 ALTO Calendars are well-suited for values encoded in the "numerical" 279 mode. Actually, Calendars can also represent metrics in other modes 280 and having considered as time-varying values. For example, types of 281 Cost values such as JSONBool can also be expressed as calendars, as 282 their value may be 'true' or 'false' depending on given time periods 283 or likewise, values represented by strings, such as "medium", "high", 284 "low", "blue", "open" . 286 Note also that a Calendar is suitable as well for time-varying 287 metrics provided in the "ordinal" mode, if these values are time- 288 varying and their update is carefully managed by the ALTO Server. 290 2.2.2. Compatibility with legacy ALTO Clients 292 The ALTO protocol extensions for Cost Calendars have been defined so 293 as to ensure that Calendar capable ALTO Servers can provide legacy 294 ALTO Clients with legacy information resources as well. That is a 295 legacy ALTO Client can request resources and receive responses as 296 specified in RFC7285. 298 A Calendar-aware ALTO Server MUST implement the base protocol 299 specified in RFC7285. 301 When a metric is available as a calendar, it MUST be available as a 302 single value as well. 304 For compatibility with legacy ALTO Clients specified in RFC7285, 305 calendared information resources are not applicable for full cost 306 maps for the following reason: a legacy ALTO client would receive a 307 calendared cost map via an HTTP 'GET' command. As specified in 308 section 8.3.7 of RFC7285, it will ignore the Calendar Attributes 309 indicated in the "meta" of the responses. Therefore, lacking 310 information on calendar attributes, it will not be able to correctly 311 interpret and process the values of the received array of calendar 312 cost values. 314 Therefore, calendared information resources MUST be requested via the 315 Filtered Cost Map Service or the Endpoint Cost Service, using a POST 316 method. 318 3. ALTO Calendar specification: IRD extensions 320 The Calendar attributes in the IRD information resources capabilities 321 carry constant dateless values. A calendar is associated with an 322 information resource rather than a cost type. For example, a Server 323 can provide a "routingcost" calendar for the Filtered Cost Map 324 Service at a granularity of one day and a "routingcost" calendar for 325 the Endpoint Cost service at a finer granularity but for a limited 326 number of endpoints. 328 3.1. Calendar attributes in the IRD resources capabilities 330 When for an applicable resource, an ALTO Server provides a Cost 331 Calendar for a given Cost Type, it MUST indicate this in the IRD 332 capabilities of this resource, by an object of type 333 'CalendarAttributes', associated with this Cost Type and specified 334 below. 336 The capabilities of a Calendar-aware information resource entry have 337 a member named "calendar-attributes" which is an array of objects of 338 type CalendarAttributes. It is necessary to use an array because of 339 resources such as Filtered Cost Map and Endpoint Cost Map, for which 340 the member "cost-type-names" is an array of 1 or more values. 342 A member "calendar-attributes" MUST appear only once for each 343 applicable cost type name of a resource entry. If "calendar- 344 attributes" are specified several times for a same "cost-type-name" 345 in the capabilities of a resource entry, the ALTO client SHOULD 346 ignore any additional occurrence of "calendar-attributes", for this 347 cost type name. 349 An ALTO Client should assume that the time interval size specified in 350 the IRD is the smallest possible one that the ALTO Server can 351 provide. The Client can aggregate cost values on its own if it needs 352 a larger granularity. 354 CalendarAttributes calendar-attributes <1..*>; 356 object{ 357 JSONString cost-type-names <1..*>; 358 JSONString time-interval-size; 359 JSONNumber number-of-intervals; 360 } CalendarAttributes; 362 o "cost-type-names": 364 * An array of one or more elements indicating the cost-type-names 365 in the IRD entry to which the capabilities apply. 367 o "time-interval-size": 369 * is the duration of an ALTO calendar time interval. A "time- 370 interval-size" value contains 2 entities separated by exactly 371 one whitespace: a JSONNumber and a string representing a time 372 unit and taking values in {second, minute, hour, day, week, 373 month, year}. Example values are: "5 minute" , "2 hour", 374 meaning that each calendar value applies on a time interval 375 that lasts respectively 5 minutes and 2 hours. 377 o "number-of-intervals": 379 * the integer number of values of the cost calendar array, at 380 least equal to 1. 382 - Attribute "cost-type-name" , if used, provides a better readability 383 to the calendar attributes specified in the IRD and avoids confusion 384 with calendar attributes of other cost-types. 386 - Multiplying Attributes 'time-interval-size' and 'number-of- 387 intervals' provides the duration of the provided calendar. For 388 example an ALTO Server may provide a calendar for ALTO values 389 changing every 'time-interval-size' equal to 5 minutes. If 'number- 390 of-intervals' has the value 12, then the duration of the provided 391 calendar is "1 hour". 393 3.2. Calendars in a delegate IRD 395 One option to clarify IRD resources is that a "root" ALTO Server 396 implementing base protocol resources delegates "specialized" 397 information resources such as the ones providing Cost Calendars to 398 another ALTO Server running in a subdomain specified with its URI in 399 the "root" ALTO Server. This option is described in Section 9.2.4 400 "Delegation using IRDs" of RFC7285. 402 This document provides an example, where a "root" ALTO Server runs in 403 a domain called "alto.example.com". It delegates the announcement of 404 Calendars capabilities to an ALTO Server running in a subdomain 405 called "custom.alto.example.com". The location of the "delegate 406 Calendar IRD" is assumed to be indicated in the "root" IRD by the 407 resource entry: "custom-calendared-resources". 409 Another advantage is that some Cost Types for some resources may be 410 more advantageous as Cost Calendars and it makes few sense to get 411 them as a single value. For example, Cost Types with predictable and 412 frequently changing values, calendared in short time intervals such 413 as a minute. 415 3.3. Example IRD with ALTO Cost Calendars 417 The cost types in this example are either specified in the base ALTO 418 protocol or may be specified in other drafts see 419 [draft-ietf-alto-performance-metrics] or defined in this draft for 420 illustrative purposes. In this example, the available cost metrics 421 are indicated in the "meta" field by cost type names "num- 422 routingcost", "num-latency", "num-pathbandwidth" and "string-quality- 423 status". Metrics "routingcost", "latency" and "bandwidthscore" are 424 available in the "numerical" Cost Mode. Metric "quality-status" is 425 available in the "string" Cost Mode. 427 The example IRD includes 2 particular URIs providing calendars: 429 o "http://custom.alto.example.com/calendar/costmap/filtered": a 430 filtered cost map in which calendar capabilities are indicated for 431 cost type names: "num-routingcost", "num-pathbandwidth" and 432 "string-service-status", 434 o "http://custom.alto.example.com/calendar/endpointcost/lookup": an 435 endpoint cost map in which calendar capabilities are indicated for 436 cost type names: "num-routingcost", "num-latency", "num- 437 pathbandwidth", "string-service-status". 439 The design of the Calendar capabilities allows that some calendars on 440 a cost type name are available in several information resources with 441 different Calendar Attributes. This is the case for calendars on 442 "num-routingcost", "num-pathbandwidth" and "string-service-status" , 443 available in both the Filtered Cost map and Endpoint Cost Service, 444 but with different time interval sizes for "num-pathbandwidth" and 445 "string-service-status". 447 GET /calendars-directory HTTP/1.1 448 Host: custom.alto.example.com 449 Accept: application/alto-directory+json,application/alto-error+json 450 --------------- 452 HTTP/1.1 200 OK 453 Content-Length: [TODO] 454 Content-Type: application/alto-directory+json 456 { 457 "meta" : { 458 "cost-types": { 459 "num-routingcost": { 460 "cost-mode" : "numerical", 461 "cost-metric" : "routingcost" 462 }, 463 "num-latency": { 464 "cost-mode" : "numerical", 465 "cost-metric": "latency" 466 }, 467 "num-pathbandwidth": { 468 "cost-mode" : "numerical", 469 "cost-metric": "bandwidthscore", 470 }, 471 "string-qual-status": { 472 "cost-mode" : "string", 473 "cost-metric": "quality-status", 474 } 475 ... other meta ... 476 }, 478 "resources" : { 479 "filtered-cost-map-calendar" : { 480 "uri" : 481 "http://custom.alto.example.com/calendar/costmap/filtered", 482 "media-type" : "application/alto-costmap+json", 483 "accepts" : "application/alto-costmapfilter+json", 484 "capabilities" : { 485 "cost-constraints" : true, 486 "cost-type-names" : [ "num-routingcost", 487 "num-pathbandwidth", 488 "string-service-status" ], 489 "calendar-attributes" : [ 490 {"cost-type-names" : [ "num-routingcost", 491 "num-pathbandwidth" ], 492 "time-interval-size" : "1 hour", 493 "number-of-intervals" : 24 494 }, 495 {"cost-type-names" : [ "string-service-status" ], 496 "time-interval-size" : "30 minute", 497 "number-of-intervals" : 48 498 } 499 ] // end calendar-attributes 500 "uses": [ "my-default-network-map" ] 501 } 502 }, 504 "endpoint-cost-calendar-map" : { 505 "uri" : 506 "http://custom.alto.example.com/calendar/endpointcost/lookup", 507 "media-type" : "application/alto-endpointcost+json", 508 "accepts" : "application/alto-endpointcostparams+json", 509 "capabilities" : { 510 "cost-constraints" : true, 511 "cost-type-names" : [ "num-routingcost", 512 "num-latency", 513 "num-pathbandwidth", 514 "string-service-status" ], 515 "calendar-attributes" : [ 516 {"cost-type-names" : [ "num-routingcost" ], 517 "time-interval-size" : "1 hour", 518 "number-of-intervals" : 24 519 }, 520 {"cost-type-names" : [ "num-latency" ], 521 "time-interval-size" : "5 minute", 522 "number-of-intervals" : 12 523 }, 524 {"cost-type-names" : [ "num-pathbandwidth" ], 525 "time-interval-size" : "1 minute", 526 "number-of-intervals" : 60 527 }, 528 {"cost-type-names" : [ "string-service-status" ], 529 "time-interval-size" : "2 minute", 530 "number-of-intervals" : 30 531 } 532 ] // Calendar attributes 533 } // ECM capab 534 } //info resource N 535 } // ressources 537 In this example IRD, for the Filtered Cost map Service: 539 o the Calendar for 'num-routingcost' and 'num-pathbandwidth' is an 540 array of 24 values each provided on a time interval lasting 1 541 hour. 543 o the Calendar for "string-service-status": "is an array of 48 544 values each provided on a time interval lasting 30 minutes. 546 For the Endpoint Cost service: 548 o the Calendar for 'num-routingcost': is an array of 24 values each 549 provided on a time interval lasting 1 hour. 551 o the Calendar for 'latency': is an array of 12 values each provided 552 on a time interval lasting 5 minutes. 554 o the Calendar for 'num-pathbandwidth': is an array of 60 values 555 each provided on a time interval lasting 1 minute. 557 o the Calendar for "string-service-status": "is an array of 30 558 values each provided on a time interval lasting 2 minutes. 560 4. ALTO Calendar specification: Service Information Resources 562 This section documents the individual information resources defined 563 to provide the Calendared information services defined in this 564 document. 566 The reference time zone for the provided time values is GMT because 567 the option chosen to express the time format is the HTTP header 568 fields format: 570 Date: Tue, 15 Nov 2014 08:12:31 GMT 572 4.1. Calendar extensions for filtered cost maps 574 A legacy ALTO client requests and gets Filtered Cost Map responses as 575 specified in RFC7285. 577 4.1.1. Calendar extensions in Filtered Cost Map requests 579 The input parameters of a "legacy" request for a filtered cost map, 580 defined by object ReqFilteredCostMap in section 11.3.2 of RFC7285, 581 are augmented with one additional member. 583 A Calendar-aware ALTO client requesting a Calendar on a given Cost 584 Type for a filtered cost map resource having Calendar capabilities 585 MUST add the following field to its input parameters: 587 JSONBoolean calendared<1..*>; 589 This field is an array of 1 to N boolean values, where N is the 590 number of requested metrics. Each boolean value indicates whether or 591 not the ALTO Server should provide the values for this Cost Type as a 592 calendar. The array MUST contain exactly N boolean values, otherwise 593 the server returns an error. 595 This field SHOULD NOT be specified if no member "calendar-attributes" 596 is specified in this information resource. 598 If a value of field 'calendared' is 'true' for a cost type name for 599 which no calendar attributes have been specified: a Calendar-aware 600 Server will return a response with a single cost value as specified 601 in RFC 7285. 603 If this field is not present, it MUST be assumed to have only values 604 equal to 'false'. 606 A Calendar-aware ALTO client supporting single cost type values, as 607 specified in RFC7285, MUST provide an array of 1 element: 609 "calendared" : [true]; 611 A Calendar-aware ALTO client that is also Multi-Cost aware MUST 612 provide an array of N values set to 'true' or 'false', depending 613 whether it wants the applicable Cost Type values as a single or 614 calendared value. 616 4.1.2. Calendar extensions in Filtered Cost Map responses 618 The calendared costs are JSONArrays instead of JSONNumbers for the 619 legacy ALTO implementation. All arrays have a number of values equal 620 to 'number-of-intervals'. 622 The "meta" field of a Calendared Filtered Cost Map response MUST 623 include at least: 625 o if the ALTO Client supports cost values for one Cost Type at a 626 time only: the "meta" fields specified in RFC 7285 for these 627 information service responses: 629 * "dependent-vtags ", 631 * "cost-type" field. 633 o if the ALTO Client supports cost values for several Cost Types at 634 a time, as specified in [RFC8189] : the "meta" fields specified in 635 [RFC8189] for these information service responses: 637 * "dependent-vtags ", 639 * "cost-type" field with value set to '{}', for backwards 640 compatibility with RFC7285. 642 * "multi-cost-types" field. 644 o If the client request does not provide member "calendared" or if 645 it provides it with a value equal to 'false', for all the 646 requested Cost Types, then the ALTO Server response is exactly as 647 specified in RFC 7285 [RFC7285] and [RFC8189]. 649 o If the value of member "calendared" is equal to 'false' for a 650 given requested Cost Type, the ALTO Server must return, for these 651 Cost Types, a single cost value as specified in RFC 7285. 653 In addition, the "meta" field of a Calendared Filtered Cost map 654 response MUST include the member "calendar-response-attributes" for 655 the requested information resource, together with the values provided 656 by the ALTO Server for these attributes. This member is an array of 657 objects of type "CalendarResponseAttributes", defined as follows: 659 CalendarResponseAttributes calendar-response-attributes <1..*>; 661 object{ 662 [JSONString cost-type-names <1..*>]; 663 JSONString calendar-start-time; 664 JSONString time-interval-size; 665 JSONNumber number-of-intervals; 666 [JSONNumber repeated;] 667 } CalendarResponseAttributes; 669 Object CalendarResponseAttributes has the following attributes: 671 o "cost-type-names": member indicating the cost-type-names to which 672 the capabilities apply. This field MUST appear in responses to 673 Multi-Cost ALTO requests. 675 o "calendar-start-time": indicates the date at which the first value 676 of the calendar applies. By default, the value provided for the 677 "calendar-start-time" attribute SHOULD be no later than the 678 request date. 680 o "time-interval-size": as specified in section "Calendar attributes 681 in the IRD resources capabilities", 683 o "number-of-intervals": as specified in section "Calendar 684 attributes in the IRD resources capabilities", 686 o "repeated": is an optional field provided for Calendars. It is an 687 integer N greater or equal to '1' that indicates how many 688 iterations of the calendar value array starting at the date 689 indicated by "calendar-start-time" have the same values. The 690 number N includes the provided iteration. 692 Using the member "repeated" helps minimizing on the wire data 693 exchange: by providing it, an ALTO Server will avoid unecessary 694 processing of requests for Calendars with unchanged values while it 695 allows ALTO Clients to save their resources as well. 697 For example: if the "calendar-start-time" member has value "Mon, 30 698 Jun 2014 at 00:00:00 GMT" and if the value of member "repeated" is 699 equal to 4, it means that the calendar values are the same values on 700 Monday, Tuesday, Wednesday and Thursday. The ALTO Client thus may 701 use the same calendar for the next 4 duration periods following 702 "calendar-start-time". 704 4.1.3. Use case and example: FCM with a bandwidth Calendar 706 An example of non-real time information that can be provisioned in a 707 'calendar' is the expected path bandwidth. While the transmission 708 rate can be measured in real time by end systems, the operator of a 709 data center is in the position of formulating preferences for given 710 paths, at given time periods for example to avoid traffic peaks due 711 to diurnal usage patterns. In this example, we assume that an ALTO 712 Client requests a bandwidth calendar as specified in the IRD to 713 schedule its bulk data transfers as described in the use cases. 715 In the example IRD, calendars for cost type name "num-pathbandwidth" 716 are available for the information resources: "filtered-cost-calendar- 717 map" and "endpoint-cost-calendar-map". The ALTO Client requests a 718 calendar for "num-pathbandwidth" via a POST request for a filtered 719 cost map. 721 We suppose in this example that the ALTO Client sends its request on 722 Tuesday July 1st 2014 at 13:15 723 POST /calendar/costmap/filtered HTTP/1.1 724 Host: alto.example.com 725 Content-Length: [TODO] 726 Content-Type: application/alto-costmapfilter+json 727 Accept: application/alto-costmap+json,application/alto-error+json 729 { 730 "cost-type" : {"cost-mode" : "numerical", 731 "cost-metric" : "bandwidthscore"}, 732 "calendared" : [true], 734 "pids" : { 735 "srcs" : [ "PID1", "PID2" ], 736 "dsts" : [ "PID1", "PID2", "PID3" ] 737 } 738 } 740 HTTP/1.1 200 OK 741 Content-Length: [TODO] 742 Content-Type: application/alto-costmap+json 744 { 745 "meta" : { 746 "dependent-vtags" : [...], 747 "cost-type" : {"cost-mode" : "numerical", 748 "cost-metric" : "bandwidthscore"}, 749 "calendar-response-attributes" : [ 750 "calendar-start-time" : Tue, 1 Jul 2014 13:00:00 GMT, 751 "time-interval-size" : "2 hour", 752 "number-of-intervals" : 12 753 ] 754 }, 756 "cost-map" : { 757 "PID1": { "PID1": [v1,v2, ... v12], 758 "PID2": [v1,v2, ... v12], 759 "PID3": [v1,v2, ... v12] }, 760 "PID2": { "PID1": [v1,v2, ... v12], 761 "PID2": [v1,v2, ... v12], 762 "PID3": [v1,v2, ... v12] } 763 } 764 } 766 4.2. Calendar extensions in the Endpoint Cost Service 768 This document extends the Endpoint Cost Service, as defined in 769 {11.5.1} of [RFC7285], by adding new input parameters and 770 capabilities, and by returning JSONArrays instead of JSONNumbers as 771 the cost values. The media type {11.5.1.1} and HTTP method 772 {11.5.1.2} are unchanged. 774 4.2.1. Calendar specific input in Endpoint Cost requests 776 The extensions to the requests for calendared Endpoint Cost Maps are 777 the same as for the Filtered Cost Map Service, specified in section 778 Section 4.1.1 of this draft. 780 The ReqEndpointCostMap object for a Calendared ECM request will have 781 the following format: 783 object { 784 [CostType cost-type;] 785 [CostType multi-cost-types<1..*>;] 786 [JSONBoolean calendared<1..*>;] 787 EndpointFilter endpoints; 788 } ReqEndpointCostMap; 790 object { 791 [TypedEndpointAddr srcs<0..*>;] 792 [TypedEndpointAddr dsts<0..*>;] 793 } EndpointFilter; 795 4.2.2. Calendar attributes in the Endpoint Cost response 797 The "meta" field of a Calendared Endpoint Cost response MUST include 798 at least: 800 o if the ALTO Client supports cost values for one Cost Type at a 801 time only: the "meta" fields specified in {11.5.1.6} of RFC 7285 802 for the Endpoint Cost response: 804 * "cost-type" field. 806 o if the ALTO Client supports cost values for several Cost Types at 807 a time, as specified in [RFC8189] : the "meta" fields specified in 808 [RFC8189] for the the Endpoint Cost response: 810 * "cost-type" field with value set to '{}', for backwards 811 compatibility with RFC7285. 813 * "multi-cost-types" field. 815 If the client request does not provide member "calendared" or if it 816 provides it with a value equal to 'false', for all the requested Cost 817 Types, then the ALTO Server response is exactly as specified in RFC 818 7285 [RFC7285] and [RFC8189]. 820 If the ALTO client provides member "calendared" in the input 821 parameters with a value equal to 'true' for given requested Cost 822 Types, the "meta" member of a Calendared Endpoint Cost response MUST 823 include, for these Cost Types, the same additional member "calendar- 824 response-attributes", as specified for the Filtered Cost Map Service. 825 The Server response is thus changed as follows, w.r.t RFC 7285 and 826 [RFC8189]: 828 o the "meta" member has one additional field 829 "CalendarResponseAttributes", as specified for the Filtered Cost 830 Map Service, 832 o the calendared costs are JSONArrays instead of JSONNumbers for the 833 legacy ALTO implementation. All arrays have a number of values 834 equal to 'number-of-intervals'. 836 If the value of member "calendared" is equal to 'false' for a given 837 requested Cost Type, the ALTO Server must return, for these Cost 838 Types, a single cost value as specified in RFC 7285. 840 4.2.3. Use case and example: ECS with a routingcost Calendar 842 Let us assume an Application Client is located in an end system with 843 limited resources and having an access to the network that is either 844 intermittent or provides an acceptable quality in limited but 845 predictable time periods. Therefore, it needs to both schedule its 846 resources greedy networking activities and its ALTO transactions. 848 The Application Client has the choice to trade content or resources 849 with a set of Endpoints and needs to decide with which one it will 850 connect and at what time. For instance, the Endpoints are spread in 851 different time-zones, or have intermittent access. In this example, 852 the 'routingcost' is assumed to be time-varying, with values provided 853 as ALTO Calendars. 855 The ALTO Client associated with the Application Client queries an 856 ALTO Calendar on 'routingcost' and will get the Calendar covering the 857 24 hours time period "containing" the date and time of the ALTO 858 client request. 860 For Cost Type 'num-routingcost', the solicited ALTO Server has 861 defined 3 different daily patterns each represented by a Calendar, to 862 cover the week of Monday June 30th at 00:00 to Sunday July 6th 23:59: 864 - C1 for Monday, Tuesday, Wednesday, Thursday, (week days) 866 - C2 for Saturday, Sunday, (week end) 868 - C3 for Friday (maintenance outage on July 4, 2014 from 02:00:00 GMT 869 to 04:00:00 GMT, or big holiday such as New Year evening). 871 In the following example, the ALTO Client sends its request on 872 Tuesday July 1st 2014 at 13:15. 874 POST /calendar/endpointcost/lookup HTTP/1.1 875 Host: alto.example.com 876 Content-Length: [TODO] 877 Content-Type: application/alto-endpointcostparams+json 878 Accept: application/alto-endpointcost+json,application/alto-error+json 880 { 881 "cost-type" : {"cost-mode" : "numerical", 882 "cost-metric" : "routingcost"}, 883 "calendared" : [true], 884 "endpoints" : { 885 "srcs": [ "ipv4:192.0.2.2" ], 886 "dsts": [ 887 "ipv4:192.0.2.89", 888 "ipv4:198.51.100.34", 889 "ipv4:203.0.113.45", 890 "ipv6:2000::1:2345:6789:abcd" 891 ] 892 } 893 } 895 HTTP/1.1 200 OK 896 Content-Length: [TODO] 897 Content-Type: application/alto-endpointcost+json 899 { 900 "meta" : { 901 "cost-type" : {"cost-mode" : "numerical", 902 "cost-metric" : "routingcost"}, 903 "calendar-response-attributes" : [ 904 { "calendar-start-time" : Mon, 30 Jun 2014 00:00:00 GMT, 905 "time-interval-size" : "1 hour", 906 "number-of-intervals" : 24, 907 "repeated": 4 } 908 ], 909 } // end meta 911 "endpoint-cost-map" : { 912 "ipv4:192.0.2.2": { 913 "ipv4:192.0.2.89" : [v1, v2, ... v24], 914 "ipv4:198.51.100.34" : [v1, v2, ... v24], 915 "ipv4:203.0.113.45" : [v1, v2, ... v24], 916 "ipv6:2000::1:2345:6789:abcd" : [v1, v2, ... v24] 917 } 918 } 919 } 920 When the Client gets the Calendar for "routingcost", it sees that the 921 "calendar-start-time" is Monday at 00h00 GMT and member "repeated" is 922 equal to '4'. It understands that the provided values are valid 923 until Thursday included and will only need to get a Calendar update 924 on Friday. 926 4.2.4. Use case and example: ECS with a multi-cost calendar for 927 routingcost and latency 929 In this example, it is assumed that the ALTO Server implements multi- 930 cost capabilities, as specified in [RFC8189] . That is, an ALTO 931 client can request and receive values for several cost types in one 932 single transaction. An illustrating use case is a path selection 933 done on the basis of 2 metrics: routing cost and latency. 935 As in the previous example, the IRD indicates that the ALTO Server 936 provides "routingcost" Calendars in terms of 24 time intervals of 1 937 hour each. 939 For metric "latency", the IRD indicates that the ALTO Server provides 940 Calendars in terms of 12 time intervals values lasting each 5 941 minutes. 943 In the following example transaction, the ALTO Client sends its 944 request on Tuesday July 1st 2014 at 13:15. 946 POST calendar/endpointcost/lookup HTTP/1.1 947 Host: alto.example.com 948 Content-Length: [TODO] 949 Content-Type: application/alto-endpointcostparams+json 950 Accept: application/alto-endpointcost+json,application/alto-error+json 952 { 953 "cost-type" : {}, 954 "multi-cost-types" : [ 955 {"cost-mode" : "numerical", "cost-metric" : "routingcost"}, 956 {"cost-mode" : "numerical", "cost-metric" : "latency"} 957 ], 958 "calendared" : [true, true], 959 "endpoints" : { 960 "srcs": [ "ipv4:192.0.2.2" ], 961 "dsts": [ 962 "ipv4:192.0.2.89", 963 "ipv4:198.51.100.34", 964 "ipv4:203.0.113.45", 965 "ipv6:2000::1:2345:6789:abcd" 966 ] 967 } 969 } 971 HTTP/1.1 200 OK 972 Content-Length: [TODO] 973 Content-Type: application/alto-endpointcost+json 975 { 976 "meta" : { 977 "multi-cost-types" : [ 978 {"cost-mode" : "numerical", "cost-metric" : "routingcost"}, 979 {"cost-mode" : "numerical", "cost-metric" : "latency"} 980 ], 981 "calendar-response-attributes" : [ 982 { "cost-type-name : num-routingcost" 983 "calendar-start-time" : Mon, 30 Jun 2014 00:00:00 GMT, 984 "time-interval-size" : "1 hour", 985 "number-of-intervals" : 24, 986 "repeated": 4 }, 987 { "cost-type-name : num-latency" 988 "calendar-start-time" : Tue, 1 Jul 2014 13:00:00 GMT, 989 "time-interval-size" : "5 minute", 990 "number-of-intervals" : 12} 991 ], 992 } // end meta 994 "endpoint-cost-map" : { 995 "ipv4:192.0.2.2": { 996 "ipv4:192.0.2.89" : [[r1, r2, ... r24], [l1, l2, ... l12]], 997 "ipv4:198.51.100.34" : [[r1, r2, ... r24], [l1, l2, ... l12]], 998 "ipv4:203.0.113.45" : [[r1, r2, ... r24], [l1, l2, ... l12]], 999 "ipv6:2000::1:2345:6789:abcd" : [[r1, r2, ... r24], 1000 [l1, l2, ... l12]] 1001 } 1002 } 1003 } 1005 When receiving the response, the client sees that the calendar values 1006 for 'routing cost' are repeated for 4 iterations. Therefore, in its 1007 next requests until the routing cost calendar is expected to change, 1008 the client will only need to request a calendar for "latency". 1010 Without the ALTO Calendar extensions, the ALTO client would have no 1011 clue on the dynamicity of the metric value change and would spend 1012 needless time requesting values at an inappropriate pace. In 1013 addition, without the Multi-Cost ALTO capabilities, the ALTO client 1014 would duplicate this waste of time as it would need to send one 1015 request per cost metric. 1017 5. IANA Considerations 1019 This document does not define any new media types or introduce any 1020 new IANA considerations. 1022 6. Security Considerations 1024 Conveying ALTO Cost Calendars tends to reduce the on-the-wire data 1025 exchange volume compared to multiple single cost ALTO transactions, 1026 as an application has a set of time-dependent values upon which it 1027 can plan its connections in advance with no need for the ALTO Client 1028 to query information at each time. Additionally, the Calendar 1029 response attribute "repeated", when provided, saves additional data 1030 exchanges in that it indicates that the ALTO Client does not need to 1031 query Calendars during a period indicated by this attribute. 1033 7. Acknowledgements 1035 The authors would like to thank Fred Baker, Li Geng, Diego Lopez, He 1036 Peng and Haibin Song for fruitful discussions and feedback on earlier 1037 draft versions. Dawn Chan, Yichen Qian and Jensen Zhang provided 1038 substantial review feedback and suggestions to the protocol design. 1040 8. References 1042 8.1. Normative References 1044 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1045 Requirement Levels", BCP 14, RFC 2119, 1046 DOI 10.17487/RFC2119, March 1997, 1047 . 1049 [RFC7285] R. Alimi, R. Yang, R. Penno, Eds., "ALTO Protocol, IETF 1050 RFC 7285", September 2014. 1052 [RFC8189] S. Randriamasy, W. Roome, N. Schwan, "Multi-Cost 1053 Application-Layer Traffic Optimization (ALTO), IETF RFC 1054 8189", October 2017. 1056 8.2. Informative References 1058 [draft-ietf-alto-performance-metrics] 1059 Q. Wu, Y. Yang, Y. Lee, D. Dhody, S. Randriamasy, "ALTO 1060 Performance Cost Metrics (work in progress)", July 2017. 1062 [RFC5693] Seedorf, J. and E. Burger, "Application-Layer Traffic 1063 Optimization (ALTO) Problem Statement", RFC 5693, 1064 DOI 10.17487/RFC5693, October 2009, 1065 . 1067 Authors' Addresses 1069 Sabine Randriamasy 1070 Nokia Bell Labs 1071 Route de Villejust 1072 NOZAY 91460 1073 FRANCE 1075 Email: Sabine.Randriamasy@nokia-bell-labs.com 1077 Richard Yang 1078 Yale University 1079 51 Prospect st 1080 New Haven, CT 06520 1081 USA 1083 Email: yry@cs.yale.edu 1085 Qin Wu 1086 Huawei 1087 101 Software Avenue, Yuhua District 1088 Nanjing, Jiangsu 210012 1089 China 1091 Email: sunseawq@huawei.com 1093 Lingli Deng 1094 China Mobile 1095 China 1097 Email: denglingli@chinamobile.com 1099 Nico Schwan 1100 Thales Deutschland 1101 Lorenzstrasse 10 1102 Stuttgart 70435 1103 Germany 1105 Email: nico.schwan@thalesgroup.com