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Randriamasy 3 Internet-Draft Nokia Bell Labs 4 Intended status: Standards Track R. Yang 5 Expires: January 9, 2017 Yale University 6 Q. Wu 7 Huawei 8 L. Deng 9 China Mobile 10 N. Schwan 11 Thales Deutschland 12 July 08, 2016 14 ALTO Cost Calendar 15 draft-randriamasy-alto-cost-calendar-06 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 costs enabling an ALTO Server to provide "Cost 34 Calendars". These capabilities are applicable to time-sensitive ALTO 35 metrics. With ALTO Cost Calendars, an ALTO Server exposes ALTO Cost 36 Values in JSON arrays where each value corresponds to a given time 37 interval. The time intervals as well as other Calendar attributes 38 are specified in the IRD and ALTO Server responses. 40 Requirements Language 42 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 43 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 44 document are to be interpreted as described in RFC 2119 [RFC2119]. 46 Status of This Memo 48 This Internet-Draft is submitted in full conformance with the 49 provisions of BCP 78 and BCP 79. 51 Internet-Drafts are working documents of the Internet Engineering 52 Task Force (IETF). Note that other groups may also distribute 53 working documents as Internet-Drafts. The list of current Internet- 54 Drafts is at http://datatracker.ietf.org/drafts/current/. 56 Internet-Drafts are draft documents valid for a maximum of six months 57 and may be updated, replaced, or obsoleted by other documents at any 58 time. It is inappropriate to use Internet-Drafts as reference 59 material or to cite them other than as "work in progress." 61 This Internet-Draft will expire on January 9, 2017. 63 Copyright Notice 65 Copyright (c) 2016 IETF Trust and the persons identified as the 66 document authors. All rights reserved. 68 This document is subject to BCP 78 and the IETF Trust's Legal 69 Provisions Relating to IETF Documents 70 (http://trustee.ietf.org/license-info) in effect on the date of 71 publication of this document. Please review these documents 72 carefully, as they describe your rights and restrictions with respect 73 to this document. Code Components extracted from this document must 74 include Simplified BSD License text as described in Section 4.e of 75 the Trust Legal Provisions and are provided without warranty as 76 described in the Simplified BSD License. 78 Table of Contents 80 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 81 2. Overview of ALTO Cost Calendars . . . . . . . . . . . . . . . 5 82 2.1. ALTO Cost Calendar information features . . . . . . . . . 5 83 2.2. ALTO Calendar design characteristics . . . . . . . . . . 6 84 2.2.1. ALTO Cost Calendar for all cost modes . . . . . . . . 7 85 2.2.2. Compatibility with legacy ALTO Clients . . . . . . . 7 86 3. ALTO Calendar specification: IRD extensions . . . . . . . . . 7 87 3.1. Calendar attributes in the IRD resources capabilities . . 8 88 3.2. Calendars in a delegate IRD . . . . . . . . . . . . . . . 9 89 3.3. Example IRD with ALTO Cost Calendars . . . . . . . . . . 9 90 4. ALTO Calendar specification: Service Information Resources . 12 91 4.1. Calendar extensions for Filtered Cost Maps . . . . . . . 13 92 4.1.1. Calendar extensions in Filtered cost map requests . . 13 93 4.1.2. Calendar extensions in Filtered Cost map responses . 14 94 4.1.3. Example transaction for a FCM with a bandwidth 95 Calendar . . . . . . . . . . . . . . . . . . . . . . 15 96 4.2. Calendar extensions in the Endpoint Cost Map Service . . 17 97 4.2.1. Calendar specific input in Endpoint cost map 98 requests . . . . . . . . . . . . . . . . . . . . . . 17 99 4.2.2. Calendar attributes in the Endpoint Cost Map response 17 100 4.2.3. Example transaction for the ECS with a routingcost 101 Calendar . . . . . . . . . . . . . . . . . . . . . . 18 102 4.2.4. Example transaction for the ECS with a calendar for 103 both routingcost and latency . . . . . . . . . . . . 21 104 4.3. Recap of rules related to ALTO Cost Calendars . . . . . . 23 105 5. Use cases for ALTO Cost Schedule . . . . . . . . . . . . . . 23 106 5.1. Bulk Data Transfer scheduling upon bandwidth calendars . 23 107 5.1.1. Applicable example transaction . . . . . . . . . . . 24 108 5.2. Applications with limited connectivity or access to 109 datacenters . . . . . . . . . . . . . . . . . . . . . . . 25 110 5.2.1. Applicable example transaction . . . . . . . . . . . 26 111 5.3. SDN Controller guided traffic scheduling with Calendars . 26 112 5.3.1. Applicable example transaction . . . . . . . . . . . 27 113 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 27 114 6.1. Information for IANA on proposed Cost Types . . . . . . . 27 115 6.2. Information for IANA on proposed Endpoint Propeeries . . 27 116 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 27 117 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 27 118 8.1. Normative References . . . . . . . . . . . . . . . . . . 27 119 8.2. Informative References . . . . . . . . . . . . . . . . . 28 120 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 28 122 1. Introduction 124 IETF is currently standardizing the ALTO protocol which aims at 125 providing guidance to overlay applications needing to select one or 126 several hosts from a set of candidates able to provide a desired 127 resource. This guidance is based on parameters that affect 128 performance and efficiency of the data transmission between the hosts 129 such as the topological distance. The goal of ALTO is to improve the 130 Quality of Experience (QoE) in the application while optimizing 131 resource usage in the underlying network infrastructure. 133 The ALTO protocol in [RFC7285] specifies a Network Map which defines 134 groupings of endpoints in provider-defined network regions (called 135 PIDs). The Cost Map Service, Endpoint Cost Service (ECS) and 136 Endpoint Ranking Service then provide ISP-defined costs and rankings 137 for connections among the specified endpoints and PIDs and thus 138 incentives for application clients to connect to ISP preferred 139 locations, e.g. to reduce their costs. ALTO intentionally avoids 140 provisioning realtime information as explained in the ALTO Problem 141 Statement [RFC5693] and ALTO Requirements [RFC5693].Thus the current 142 Cost Map and Endpoint Cost Service are providing, for a given Cost 143 Type, exactly one path cost value. Applications have to query one of 144 these two services to retrieve the currently valid cost values. They 145 therefore need to plan their ALTO information requests according to 146 their own estimation of the frequency of cost value change. 148 With [RFC7285], an ALTO client should interpret the returned costs as 149 those at the query moment. However, Network costs can fluctuate, 150 e.g. due to diurnal patterns of traffic demand or planned events such 151 as network maintenance, holidays or highly publicized events. 152 Providing network costs for only the current time thus may not be 153 sufficient, in particular for applications that can schedule their 154 traffic in a span of time, for example by deferring backup to night 155 during traffic trough. 157 In case the ALTO Cost value changes are predicable over a certain 158 period of time and the application does not require immediate data 159 transfer, it can save time to get the whole set of cost values over 160 this period in one ALTO response. Using them to schedule data 161 transfers would allow to optimise the network resources usage and 162 QoE. ALTO Clients and Servers can also minimize their workload by an 163 appropriate scheduling of their data exchanges. 165 This document extends RFC7285 to allow an ALTO server to provide 166 network costs for a given duration of time. A sequence of network 167 costs across a time span for a given pair of network locations is 168 named an "ALTO Cost Calendar". The Filtered Cost Map Service and 169 Endpoint Cost Service are extended to provide Cost Calendars. In 170 addition to this functional ALTO enhancement, we expect to further 171 gain on storage and on the wire data exchange by gathering multiple 172 Cost Values for one Cost Type into one single ALTO Server response. 174 In this draft an "ALTO Cost Calendar" is specified by information 175 resources capabilities that are applicable to time-sensitive ALTO 176 metrics. An ALTO Cost Calendar exposes ALTO Cost Values in JSON 177 arrays where each value corresponds to a given time interval. The 178 time intervals as well as other Calendar attributes are specified in 179 the IRD and in the Server response to allow the ALTO Client to 180 interpret the received ALTO values. Last, the proposed extensions 181 for ALTO Calendars are applicable to any Cost Mode and they ensure 182 backwards compatibility with legacy ALTO clients. 184 In the rest of this document, Section 2 provides the design 185 characteristics. Sections 3 and 4 define the formal specification 186 for the IRD and the information resources. Section 5 provides non- 187 normative use cases to illustrate the usage of cost calendars. IANA 188 considerations and security considerations will be completed in 189 further versions. 191 2. Overview of ALTO Cost Calendars 193 An ALTO Cost calendar provided by the ALTO Server provides 2 194 information items: 196 o an array of values for a given metric, where each value 197 corresponds to a time interval, wher the value array can sometimes 198 be a cyclic pattern that repeats a certain number of times. 200 o attributes describing the time scope of the calendar, allowing an 201 ALTO Client to properly interpret the values, such as the size and 202 number of the intervals and the date of the starting point of the 203 calendar. 205 An ALTO Cost Calendar can be used like a "time table" to figure out 206 the best time to schedule data transfers and also to proactively 207 manage appllication traffic given predictable events such as flash 208 crowds, traffic intensive holidays and network maintenance. An ALTO 209 Cost Calendar may be viewed as a synthetic abstraction of real 210 measurements that can be historic or be a prediction for upcoming 211 time periods. 213 Most likely, the ALTO Cost Calendar would be used for the Endpoint 214 Cost Service, assuming that a limited set of feasible Endpoints for a 215 non-real time application is already identified, that they do not 216 need to be accessed immediately and that their access can be 217 scheduled within a given time period. The Filtered Cost Map service 218 is also applicable as long as the size of the Map allows it. 220 2.1. ALTO Cost Calendar information features 222 The Calendar attributes are provided in the IRD and in ALTO Server 223 responses. The IRD announces attributes with dateless values in its 224 information resources capabilities, where as attributes with time 225 dependent values are provided in the "meta" of Server responses. The 226 ALTO Cost Calendar attributes provide the following information: 228 o attributes to interpret the time scope of the Calendar value 229 array: 231 * generic time zone, 233 * applicable time interval for each calendar value: combining 234 numbers and time units to reflect for example: 1 hour, 2 235 minutes, 10 seconds, 1 week, 1 month, 237 * duration of the Calendar: e.g. the number of intervals provided 238 in the calendar. 240 o "calendar-start-date": specifying when the calendar starts, that 241 is to which date the first value of the cost calendar is 242 applicable. 244 o "repeated": an optional attribute indicating how many iterations 245 the provided calendar will have the same values, that the server 246 may use to allow the client to schedule its next request and thus 247 save its own workload by avoiding to process useless requests. 249 2.2. ALTO Calendar design characteristics 251 This draft introduces new capabilities and attributes that specify an 252 ALTO Cost Calendar. The protocol extension placeholders are: the 253 IRD, the ALTO requests and responses for Cost calendars. 255 Extensions are designed to be light and ensure backwards 256 compatibility with base protocol ALTO Clients and with other 257 extensions. It uses section 8.3.7 "Parsing of Unknown Fields" of 258 RFC7285 that writes: "Extensions may include additional fields within 259 JSON objects defined in this document. ALTO implementations MUST 260 ignore unknown fields when processing ALTO messages." 262 The calendar specific capabilities are integrated in the information 263 resources of the IRD and in the "meta" member of ALTO responses to 264 Cost Calendars requests. A calendar and its capabilities are 265 associated to a given information resource and within this 266 information resource to a given cost type. This design has several 267 advantages: 269 o it does not introduce a new mode, 271 o it does not introduce new media types, 273 o it allows an ALTO Server to offer calendar capabilities on a cost 274 type, with attributes values adapted to each information resource. 276 The Applicable Calendared information resources are: 278 o the Filtered Cost Map, 280 o the Endpoint Cost Map. 282 The ALTO Server can choose in which frequency it provides cost 283 Calendars to ALTO Clients. It may either provide calendar updates 284 starting at the request date, or carefully schedule its updates so as 285 to take profit from a potential repetition/periodicity of calendar 286 values. 288 2.2.1. ALTO Cost Calendar for all cost modes 290 Calendars are well-suited for values encoded in the 'numerical' mode. 291 However, Calendars can also represent any metric considered as time- 292 sensitive by an ALTO Server. For example, types of Cost values such 293 as JSONBool can also be expressed as calendars, as states may be 294 "true" or "false" depending on given time periods or likewise, values 295 represented by strings, such as "medium", "high", "low", "blue", 296 "open" . 298 Note also that a Calendar is applicable as well to time-sensitive 299 metrics provided in the 'ordinal' mode, if these values are time- 300 sentitive and their update is carefully managed by the ALTO Server. 302 2.2.2. Compatibility with legacy ALTO Clients 304 The ALTO protocol extensions for Cost Calendars have been defined so 305 as to ensure that Calendar capable ALTO Servers can provide legacy 306 ALTO Clients with legacy information resources as well. That is a 307 legacy ALTO Client can request resources and receive responses as 308 specified in RFC7285. 310 For compatibility with legacy ALTO Clients specified in RFC7285, 311 calendared information resources are not applicable for Cost Maps for 312 the following reason: a legacy ALTO client would receive a Calendared 313 Cost Map via an HTTP 'GET' command. As specified in section 8.3.7 of 314 RFC7285, it will ignore the Calendar Attributes indicated in the 315 "meta" of the responses. Therefore, lacking information on calendar 316 attributes, it will not be able to correctly interpret and process 317 the values of the received array of calendar cost values. 319 3. ALTO Calendar specification: IRD extensions 321 The Calendar attributes in the IRD information resources capabilities 322 carry constant dateless values. A calendars is associated to an 323 information resource rather than a cost type. For example, a Server 324 can provide a "routingcost" values calendar for the Filtered Cost Map 325 Service at a granularity of one day and a "routingcost" values 326 calendar for the Endpoint Cost service at a finer granularity but for 327 a limited number of endpoints. 329 NOTE : to cope with existing representation fomats and proposed 330 unified ALTO naming schemes proposed in the WG, the names given in 331 the current proposal may be revised in further versions. 333 3.1. Calendar attributes in the IRD resources capabilities 335 When for an applicable resource , an ALTO Server provides a Cost 336 Calendar for a given Cost Type, it MUST indicate this in the IRD 337 capabilities of this resource, by an object of type 338 'CalendarAttributes', associated to this Cost Type and specified 339 below. 341 The capabilities of a Calendar aware information resource entry have 342 a member named "calendar-attributes" which is an array of objects of 343 type CalendarAttributes. The array has as many values as cost-type- 344 names announced for the resource. It is necessary to use an array 345 because of resources such as Filtered Cost Map and Endpoint Cost Map, 346 for which the member "cost-type-names" is an array of 1 or more 347 values. If for a given cost-type-name of this ressource no Calendar 348 attributes are defined, the ALTO Server MUST replace that value in 349 the array by the symbol 'null'. 351 RULE: a member "calendar-attributes" MUST appear only once for each 352 applicable cost type name of a resource entry. If "calendar- 353 attributes" are specified several times for a same "cost-type-name" 354 in the capabilities of a resource entry, the ALTO client SHOULD 355 ignore any calendar capabilities on this "cost-type-name" for this 356 entry. 358 CalendarAttributes calendar-attributes <1..*>; 360 object{ 361 [JSONString cost-type-name;] 362 JSONString time-interval-size; 363 JSONNumber number-of-intervals; 364 } CalendarAttributes; 366 o "cost-type-name": 368 * an optional member indicating the cost-type-name in the IRD 369 entry to which the capabilities apply. If this not present, it 370 MUST be assumed to correspond to its index in the "cost-type- 371 names" list of the IRD resource entry. 373 o "time-interval-size": 375 * is the duration of an ALTO calendar time interval, expressed as 376 a time unit appended to the number of these units. The time 377 unit, ranges from "second" to "year". The number is encoded 378 with an integer. Example values are: "5 minute" , "2 hour", 379 meaning that each calendar value applies on a time interval 380 that lasts respectively 5 minutes and 2 hours. 382 o "number-of-intervals": 384 * the integer number of values of the cost calendar array, at 385 least equal to 1. 387 - Attribute "cost-type-name" , if used, provides a better readability 388 to the calendar attributes specified in the IRD and avoids confusion 389 with calendar attributes of other cost-types. 391 - Multiplying Attributes 'time-interval-size' and 'number-of- 392 intervals' provides the duration of the provided calendar. For 393 example an ALTO Server may provide a calendar for ALTO values 394 changing every 'time-interval-size' equal to 5 minutes. If 'number- 395 of-intervals' has the value 12, then the duration of the provided 396 calendar is "1 hour". 398 3.2. Calendars in a delegate IRD 400 One option to clarify IRD resources is that a "root" ALTO Server 401 implementing base protocol resources delegates "specialized" 402 information resources such as the ones providing Cost Calendars to 403 another ALTO Server running in a subdomain specified with its URI in 404 the "root" ALTO Server. This option is described in Section 9.2.4 405 "Delegation using IRDs" of RFC7285. 407 This document provides an example, where a "root" ALTO Server runs in 408 a domain called "alto.example.com". It delegates the announcement of 409 Calendars capabilities to an ALTO Server running in a subdomain 410 called "custom.alto.example.com". The location of the "delegate 411 Calendar IRD" is assumed to be indicated in the "root" IRD by the 412 resource entry: "custom-calendared-resources". 414 Another advantage is that some Cost Types for some resources may be 415 more advantageous as Cost Calendars and it makes few sense to get 416 them as a single value. For example, Cost Types with predictable and 417 frequently changing values, calendared in short time intervals such 418 as a minute. 420 3.3. Example IRD with ALTO Cost Calendars 422 The cost types in this example are either specified in the base ALTO 423 protocol or may be proposed in other drafts see 424 [draft-wu-alto-te-metrics]. In this example the available cost 425 metrics are indicated in the "meta" field by cost type names "num- 426 routingcost", "num-latency", "num-pathbandwidth" and "string-quality- 427 status". Metrics "routingcost" , 'latency' and 'Availbandwidth' are 428 available in the "numerical" Cost Mode. Metric "quality-status" is 429 available in the "string" Cost Mode. 431 This ALTO server does not provide a calendar for cost type name num- 432 AShopcount. 434 The example IRD includes 2 particular URIs providing calendars: 436 o "http://custom.alto.example.com/calendar/costmap/filtered": a 437 filtered cost map in which calendar capabilities are indicated for 438 cost type names: "num-routingcost", "num-pathbandwidth" and 439 "string-service-status", 441 o "http://custom.alto.example.com/endpointcost/calendar/lookup": an 442 endpoint cost map in which in which calendar capabilities are 443 indicated for cost type names: "num-routingcost", "num-TEpktloss", 444 "num-pathbandwidth", "string-service-status". 446 The design of the Calendar capabilities allows that some calendars on 447 a cost type name are available in several information resources with 448 different Calendar Attributes. This is the case for calendars on 449 "num-routingcost", "num-pathbandwidth" and "string-service-status" , 450 available in both the Filtered Cost map and Endpoint Cost map 451 service, but with different time interval sizes for "num- 452 pathbandwidth" and "string-service-status". 454 GET /calendars-directory HTTP/1.1 455 Host: custom.alto.example.com 456 Accept: application/alto-directory+json,application/alto-error+json 457 --------------- 459 HTTP/1.1 200 OK 460 Content-Length: [TODO] 461 Content-Type: application/alto-directory+json 463 { 464 "meta" : { 465 "cost-types": { 466 "num-routingcost": { 467 "cost-mode" : "numerical", 468 "cost-metric" : "routingcost" 469 }, 470 "num-latency": { 471 "cost-mode" : "numerical", 472 "cost-metric": "latency" 473 }, 474 "num-pathbandwidth": { 475 "cost-mode" : "numerical", 476 "cost-metric": "Availbandwidth", 477 }, 478 "string-qual-status": { 479 "cost-mode" : "string", 480 "cost-metric": "quality-status", 481 } 482 ... other meta ... 483 }, 485 "resources" : { 486 "filtered-cost-map-calendar" : { 487 "uri" : "http://custom.alto.example.com/calendar/costmap/filtered", 488 "media-type" : "application/alto-costmap+json", 489 "accepts" : "application/alto-costmapfilter+json", 490 "capabilities" : { 491 "cost-constraints" : true, 492 "cost-type-names" : [ "num-routingcost", "num-pathbandwidth", 493 "string-service-status" ], 494 "calendar-attributes" : [ 495 {"cost-type-names" : [ "num-routingcost", "num-pathbandwidth" ], 496 "time-interval-size" : "1 hour", 497 "number-of-intervals" : 24 498 }, 499 {"cost-type-names" : "string-service-status", 500 "time-interval-size" : "30 minute", 501 "number-of-intervals" : 48 502 } 503 ] // end calendar-attributes 504 "uses": [ "my-default-network-map" ] 505 } 506 }, 508 "endpoint-cost-calendar-map" : { 509 "uri" : "http://custom.alto.example.com/calendar/endpointcost/calendar/lookup", 510 "media-types" : [ "application/alto-endpointcost+json" ], 511 "accepts" : [ "application/alto-endpointcostparams+json" ], 512 "capabilities" : { 513 "cost-constraints" : true, 514 "cost-type-names" : [ "num-routingcost", "num-latency", 515 "num-pathbandwidth", "string-service-status" ], 516 "calendar-attributes" : [ 517 {"cost-type-names" : "num-routingcost", 518 "time-interval-size" : "1 hour", 519 "number-of-intervals" : 24 520 }, 521 {"cost-type-names" : "latency", 522 "time-interval-size" : "5 minute", 523 "number-of-intervals" : 12 524 }, 525 {"cost-type-names" : "num-pathbandwidth", 526 "time-interval-size" : "1 minute", 527 "number-of-intervals" : 60 528 }, 529 {"cost-type-names" : "string-service-status", 530 "time-interval-size" : "2 minute", 531 "number-of-intervals" : 30 532 }, 533 ] 534 "uses": [ "my-default-network-map" ] 535 } // ECM capab 536 } //info resource N 537 } // ressources 539 In this example IRD, for the filtered cost map service, all calendars 540 have a duration of 1 day and start in the "request-date" mode, that 541 is the "date" of first value of the array belongs to the time 542 interval "containing" the date of the request. 544 o the Calendar for 'num-routingcost': is an array of 24 values each 545 provided on a time interval lasting 1 hour. 547 o the Calendar for 'num-pathbandwidth': is an array of 24 values 548 each provided on a time interval lasting 1 hour. 550 o the Calendar for "string-service-status": "is an array of 48 551 values each provided on a time interval lasting 30 minutes. 553 For the endpoint cost map service, the cost calendars have a duration 554 of 1 day for "num-routingcost" and 1 hour for the 3 other cost type 555 names. 557 o the Calendar for 'num-routingcost': is an array of 24 values each 558 provided on a time interval lasting 1 hour. 560 o the Calendar for 'latency'': is an array of 12 values each 561 provided on a time interval lasting 5 minutes. 563 o the Calendar for 'num-pathbandwidth': is an array of 60 values 564 each provided on a time interval lasting 1 minute. 566 o the Calendar for "string-service-status": "is an array of 30 567 values each provided on a time interval lasting 2 minutes. 569 4. ALTO Calendar specification: Service Information Resources 571 This section documents the individual information resources defined 572 to provide the Calendared information services defined in this 573 document. 575 The reference time zone for the provided time values is GMT because 576 the option chosen to express the time format is the HTTP header 577 fields format: 579 Date: Tue, 15 Nov 1994 08:12:31 GMT 581 4.1. Calendar extensions for Filtered Cost Maps 583 A legacy ALTO client requests and gets filtered cost map responses as 584 specified in RFC7285. 586 4.1.1. Calendar extensions in Filtered cost map requests 588 The input parameters of a "legacy" request for a filtered cost map, 589 defined by object ReqFilteredCostMap in section 11.3.2 of RFC7285, 590 are augmented with one additional member. 592 A Calendar-aware ALTO client requesting a Calendar on a given Cost 593 Type for a Filtered Cost Map resource having Calendar capabilities 594 MUST add the following field to its input parameters: 596 JSONBoolean calendared<1..*>; 598 This field is an array of 1 to N boolean values, where N is the 599 number of requested metrics. Each boolean value indicates whether or 600 not the ALTO Server should provide the values for this Cost Type as a 601 calendar. 603 This field MUST NOT be specified if member "calendar-attributes" is 604 not present or has the value 'false' for this information resource. 606 A Calendar-aware ALTO client supporting single cost type values, as 607 specified in RFC7285, MUST provide an array of 1 element: 608 "calendared" : [true], 610 A Calendar-aware ALTO client that is also Multi-Cost aware MUST 611 provide an array of N values set to "true" or "false", depending 612 whether it wants the applicable Cost Type values as a single or 613 calendared value. 615 If this field is not present, it MUST be assumed to have only values 616 equal to "false". 618 4.1.2. Calendar extensions in Filtered Cost map responses 620 The calendared costs are JSONArrays instead of JSONNumbers for the 621 legacy ALTO implementation. All arrays have a number of values equal 622 to 'number-of-intervals'. 624 The "meta" field of a Calendared Filtered Cost map response MUST 625 include at least: 627 o if the ALTO Client supports cost values for one Cost Type at a 628 time only: the "meta" fields specified specified in RFC 7285 for 629 these information service responses: 631 * "dependent-vtags ", 633 * "cost-type" field. 635 o if the ALTO Client supports cost values for several Cost Types at 636 a time, as specified in [draft-ietf-alto-multi-cost] : the "meta" 637 fields specified in [draft-ietf-alto-multi-cost] for these 638 information service responses: 640 * "dependent-vtags ", 642 * "multi-cost-types" field. 644 In addition, the "meta" field of a Calendared Filtered Cost map 645 response MUST include the member "calendar-response-attributes" for 646 the requested information resource, together with the values provided 647 by the ALTO Server for these attributes. This member is an array of 648 objects of type "CalendarResponseAttributes", defined as follows: 650 CalendarResponseAttributes calendar-response-attributes <1..*>; 652 object{ 653 JSONString calendar-start-time; 654 JSONString time-interval-size; 655 JSONNumber number-of-intervals; 656 [JSONNumber repeated;] [OPTIONAL] 657 } CalendarResponseAttributes; 659 o "calendar-start-time": indicates the date at which the first value 660 of the calendar applies. By default, the value provided for the 661 "calendar-start-time" attribute SHOULD be no later than the 662 request date. 664 o "time-interval-size": as specified in section "Calendar attributes 665 in the IRD resources capabilities", 667 o "number-of-intervals": as specified in section "Calendar 668 attributes in the IRD resources capabilities", 670 o "repeated": is an optional field provided for Calendars. It is an 671 integer N greater or equal to '1' that indicates how many 672 iterations of the calendar value array starting at the date 673 indicated by "calendar-start-time" have the same values. The 674 number N includes the provided iteration. 676 Using the member "repeated" helps minimizing on the wire data 677 exchange: by providing it, an ALTO Server will avoid unecessary 678 processing of requests for Calendars with unchanged values while it 679 allows ALTO Clients to save their resources as well. 681 For example: if the "calendar-start-time" member has value "Mon, 30 682 Jun 2014 at 00:00:00 GMT" and if the value of member "repeated" is 683 equal to 4, it means that the calendar values are the same values on 684 Monday, Tuesday, Wednesday and Thursday. The ALTO Client thus may 685 use the same calendar for the next 4 duration periods following 686 "calendar-start-time". 688 4.1.3. Example transaction for a FCM with a bandwidth Calendar 690 An example of non-real time information that can be provisioned in a 691 'calendar' is the expected path bandwidth. While the transmission 692 rate can be measured in real time by end systems, the operator of a 693 data center is in the position of formulating preferences for given 694 paths, at given time periods for example to avoid traffic peaks due 695 to diurnal usage patterns. In this example, we assume that an ALTO 696 Client requests a bandwidth calendar as specified in the IRD to 697 shedule its bulk data transfers as described in the use cases. 699 In the example IRD, calendars for cost type name "num-pathbandwidth" 700 are available for the information resources: "filtered-cost-calendar- 701 map" and "endpoint-cost-calendar-map". The ALTO Client requests a 702 calendar for "num-pathbandwidth" via a POST request for a filtered 703 cost map. 705 We suppose in this example that the ALTO Client sends its request on 706 Tuesday July 1st 2014 at 13:15 708 POST /calendar/costmap/filtered HTTP/1.1 709 Host: alto.example.com 710 Content-Length: [TODO] 711 Content-Type: application/alto-costmapfilter+json 712 Accept: application/alto-costmap+json,application/alto-error+json 714 { 715 "cost-type" : {"cost-mode" : "numerical", "cost-metric" : "Availbandwidth"}, 716 "calendared" : [true], 718 "pids" : { 719 "srcs" : [ "PID1", "PID2" ], 720 "dsts" : [ "PID1", "PID2", "PID3" ] 721 } 722 } 724 HTTP/1.1 200 OK 725 Content-Length: [TODO] 726 Content-Type: application/alto-costmap+json 728 { 729 "meta" : { 730 "dependent-vtags" : [...], 731 "cost-type" : {"cost-mode" : "numerical", "cost-metric" : "Availbandwidth"}, 732 "calendar-response-attributes" : [ 733 "calendar-start-time" : Tue, 1 Jul 2014 13:00:00 GMT, 734 "time-interval-size" : "2 hour", 735 "numb-intervals" : 12 736 ] 737 }, 739 "cost-map" : { 740 "PID1": { "PID1": [v1,v2, ... v12], 741 "PID2": [v1,v2, ... v12], 742 "PID3": [v1,v2, ... v12] }, 743 "PID2": { "PID1": [v1,v2, ... v12], 744 "PID2": [v1,v2, ... v12], 745 "PID3": [v1,v2, ... v12] } 746 } 747 } 749 4.2. Calendar extensions in the Endpoint Cost Map Service 751 This document extends the Endpoint Cost Service, as defined in 752 {11.5.1} of [RFC7285], by adding new input parameters and 753 capabilities, and by returning JSONArrays instead of JSONNumbers as 754 the cost values. The media type (11.5.1.1} and HTTP method 755 (11.5.1.2} are unchanged. 757 4.2.1. Calendar specific input in Endpoint cost map requests 759 The extensions to the requests for calendared Endpoint Cost Maps are 760 the same as for the Filtered Cost Map Service, specified in section 761 XXXX of this draft. 763 The ReqEndpointCostMap object for a Calendared ECM request will have 764 the following format: 766 object { 767 CostType cost-type; 768 [JSONBoolean calendared<1..*>;] 769 EndpointFilter endpoints; 770 } ReqEndpointCostMap; 772 object { 773 [TypedEndpointAddr srcs<0..*>;] 774 [TypedEndpointAddr dsts<0..*>;] 775 } EndpointFilter; 777 4.2.2. Calendar attributes in the Endpoint Cost Map response 779 The "meta" field of a Calendared Endpoint Cost map response MUST 780 include at least: 782 o if the ALTO Client supports cost values for one Cost Type at a 783 time only: the "meta" fields specified in {11.5.1.6} of RFC 7285 784 for the Endpoint Cost response: 786 * "cost-type" field. 788 o if the ALTO Client supports cost values for several Cost Types at 789 a time, as specified in [draft-ietf-alto-multi-cost] : the "meta" 790 fields specified in [draft-ietf-alto-multi-cost] for the the 791 Endpoint Cost response: 793 * "multi-cost-types" field. 795 If the client request does not provide member "calendared" or if it 796 provides it with a value equal to 'false', then the ALTO Server 797 response is exactly as specified in the above cited references. 799 If the ALTO client provides member "calendared" with a value equal to 800 'true' in the input parameters, the "meta" member of a Calendared 801 Endpoint Cost Map response MUST include the same addifional member 802 "calendar-response-attributes" as specified for the Filtered Cost Map 803 Service. The Server response is thus changed as follows: 805 o the "meta" member has one additional field 806 "CalendarResponseAttributes", as specified for the Filtered Cost 807 Map Service, 809 o the calendared costs are JSONArrays instead of JSONNumbers for the 810 legacy ALTO implementation. All arrays have a number of values 811 equal to 'number-of-intervals'. 813 4.2.3. Example transaction for the ECS with a routingcost Calendar 815 Let us assume an Application Client is located in an end sytem with 816 limited resources and having an access to the network that is either 817 intermittent or provides an acceptable quality in limited but 818 predictable time periods. Therefore, it needs to both schedule its 819 resources greedy networking activities and its ALTO transactions. 821 The Application Client has the choice to trade content or resources 822 with a set of Endpoints and needs to decide with which one it will 823 connect and at what time. For instance, the Endpoints are spread in 824 different time-zones, or have intermittent access. In this example, 825 the 'routingcost' is assumed to be time sentitive with values 826 provided as ALTO Calendars. 828 The ALTO Client associated to the Application Client queries an ALTO 829 Calendar on 'routingcost' and will get the Calendar covering the 24 830 hours time period "containing" the date and time of the ALTO client 831 request. 833 For Cost Type 'num-routingcost', the sollicited ALTO Server has 834 defined 3 different daily patterns each represented by a Calendar, to 835 cover the week of Monday June 30th at 00:00 to Sunday July 6th 23:59: 837 - C1 for Monday, Tuesday, Wednesday, Thursday, (week days) 839 - C2 for Saturday, Sunday, (week end) 841 - C3 for Friday (maintenance outage on July 4, 2014 from 02:00:00 GMT 842 to 04:00:00 GMT, or big holiday such as New Year evening). 844 In the following example, the ALTO Client sends its request on 845 Tuesday July 1st 2014 at 13:15. 847 POST /calendar/endpointcost/lookup HTTP/1.1 848 Host: alto.example.com 849 Content-Length: [TODO] 850 Content-Type: application/alto-endpointcostparams+json 851 Accept: application/alto-endpointcost+json,application/alto-error+json 853 { 854 "cost-type" : {"cost-mode" : "numerical", "cost-metric" : "routingcost"}, 855 "calendared" : [true], 856 "endpoints" : { 857 "srcs": [ "ipv4:192.0.2.2" ], 858 "dsts": [ 859 "ipv4:192.0.2.89", 860 "ipv4:198.51.100.34", 861 "ipv4:203.0.113.45", 862 "ipv6:2000::1:2345:6789:abcd" 863 ] 864 } 865 } 867 HTTP/1.1 200 OK 868 Content-Length: [TODO] 869 Content-Type: application/alto-endpointcost+json 871 { 872 "meta" : { 873 "cost-type" : {"cost-mode" : "numerical", "cost-metric" : "routingcost"}, 874 "calendar-response-attributes" : [ 875 { "calendar-start-time" : Mon, 30 Jun 2014 00:00:00 GMT, 876 "time-interval-size" : "1 hour", 877 "numb-intervals" : 24, 878 "repeated": 4 } 879 ], 880 } // end meta 882 "endpoint-cost-map" : { 883 "ipv4:192.0.2.2": { 884 "ipv4:192.0.2.89" : [v1, v2, ... v24], 885 "ipv4:198.51.100.34" : [v1, v2, ... v24], 886 "ipv4:203.0.113.45" : [v1, v2, ... v24], 887 "ipv6:2000::1:2345:6789:abcd" : [v1, v2, ... v24] 888 } 889 } 890 } 891 When the Client gets the Calendar for "routingcost", it sees that the 892 "calendar-start-time" is Monday at 00h00 GMT and member "repeated" is 893 equal to '4'. It understands that the provides values are valid 894 until Thursday included and will only need to get a Calendar update 895 on Friday. 897 4.2.4. Example transaction for the ECS with a calendar for both 898 routingcost and latency 900 In this example, it is assumed that the ALTO Server implements multi- 901 cost capabilities, as specified in [draft-ietf-alto-multi-cost] . 902 That is, an ALTO client can request and receive values for several 903 cost types in one single transaction. An illustrating use case is a 904 path selection done on the basis of 2 metrics: routing cost and 905 latency. 907 As in the previous example, the IRD indicates that the ALTO Server 908 provides "routingcost" Calendars in terms of 24 time intervals of 1 909 hour each. 911 For metric "latency", the IRD indicates that the ALTO Server provides 912 Calendars in terms of 12 time intervals values lasting each 5 913 minutes. 915 In the following example transaction, the ALTO Client sends its 916 request on Tuesday July 1st 2014 at 13:15. 918 POST calendar/endpointcost/lookup HTTP/1.1 919 Host: alto.example.com 920 Content-Length: [TODO] 921 Content-Type: application/alto-endpointcostparams+json 922 Accept: application/alto-endpointcost+json,application/alto-error+json 924 { 925 "multi-cost-types" : [ 926 {"cost-mode" : "numerical", "cost-metric" : "routingcost"}, 927 {"cost-mode" : "numerical", "cost-metric" : "latency"} 928 ], 929 "calendared" : [true, true], 930 "endpoints" : { 931 "srcs": [ "ipv4:192.0.2.2" ], 932 "dsts": [ 933 "ipv4:192.0.2.89", 934 "ipv4:198.51.100.34", 935 "ipv4:203.0.113.45", 936 "ipv6:2000::1:2345:6789:abcd" 937 ] 938 } 940 } 942 HTTP/1.1 200 OK 943 Content-Length: [TODO] 944 Content-Type: application/alto-endpointcost+json 946 { 947 "meta" : { 948 "multi-cost-types" : [ 949 {"cost-mode" : "numerical", "cost-metric" : "routingcost"}, 950 {"cost-mode" : "numerical", "cost-metric" : "latency"} 951 ], 952 "calendar-response-attributes" : [ 953 { "cost-type-name : num-routingcost" 954 "calendar-start-time" : Mon, 30 Jun 2014 00:00:00 GMT, 955 "time-interval-size" : "1 hour", 956 "numb-intervals" : 24, 957 "repeated": 4 }, 958 { "cost-type-name : num-latency" 959 "calendar-start-time" : Tue, 1 Jul 2014 13:00:00 GMT, 960 "time-interval-size" : "5 minute", 961 "numb-intervals" : 12} 962 ], 963 } // end meta 965 "endpoint-cost-map" : { 966 "ipv4:192.0.2.2": { 967 "ipv4:192.0.2.89" : [[r1, r2, ... r24], [l1, l2, ... l12]], 968 "ipv4:198.51.100.34" : [[r1, r2, ... r24], [l1, l2, ... l12]], 969 "ipv4:203.0.113.45" : [[r1, r2, ... r24], [l1, l2, ... l12]], 970 "ipv6:2000::1:2345:6789:abcd" : [[r1, r2, ... r24], [l1, l2, ... l12]] 971 } 972 } 973 } 975 When receiving the response, the client sees that the calendar values 976 for 'routing cost' are repeated for 4 iterations. Therefore, in its 977 next requests until the routing cost calendar is expected to change, 978 the client will only need to request a calendar for "latency". 980 Without the ALTO Calendar extensions, the ALTO client would have no 981 clue on the dynamicity of the metric value change and would spend 982 needless time requesting values at an inappropriate pace. In 983 addition, without the Multi-Cost ALTO capabilities, the ALTO client 984 would duplicate this waste of time as it would need to send one 985 request per cost metric. 987 4.3. Recap of rules related to ALTO Cost Calendars 989 XXXXX TO BE COMPLETED + MOVED AT THE END OF THE SPECS 991 A Calendar-aware ALTO Server MUST implement the base protocol 992 specified in RFC7285. 994 If no Calendar attributes are defined for a given Cost Type, in a 995 given resource entry, the ALTO Server MUST set the value in the 996 'calendar-attributes' array to the symbol 'null' . 998 When a metric is available as a calendar, it MUST be available as a 999 single value. An ALTO Server aquiring cost values in limited time 1000 intervals only can construct a single value from the value array. 1002 Calendared information resources MUST be requested via a POST method. 1004 If this member "repeat-indication" is not present in the calendar 1005 attributes indicated in the IRD, it MUST be assumed to have a value 1006 equal to "false". 1008 5. Use cases for ALTO Cost Schedule 1010 [THIS SECTION NEEDS TO BE SHORTENED ] 1012 This section presents use cases showing the benefits of ALTO Cost 1013 calendars for applications needing to decide both "where" to connect 1014 and "when". 1016 5.1. Bulk Data Transfer scheduling upon bandwidth calendars 1018 Large Internet Content Providers (ICPs) like Facebook or YouTube, as 1019 well as CDNs rely on data replication across multiple sites and time 1020 zones to offload the core site and increase user experience through 1021 shorter latency from a local site. Typically the usage pattern of 1022 these data centers or caches follows a location dependent diurnal 1023 demand pattern. In these examples, data replication across the 1024 various locations of an ICP, leads to bulk data transfers between 1025 datacenters on a diurnal pattern. 1027 In the meantime, there is a degree of freedom on when the content is 1028 transmitted from the origin server to the caching node, or from the 1029 core site to a local site. However, scheduling these data transfers 1030 is a non-trivial task as they should not infer with the user peak 1031 demand to avoid degradation of user experience and to decrease 1032 billing costs for the datacenter operator by leveraging off-peak 1033 hours for the transfer. 1035 As a result, these ICPs need to have a good knowledge on the link 1036 utilization patterns between the different datacenters before making 1037 an efficient scheduling decision. While usage data today is already 1038 gathered and used to schedule data transfers, provisioning these data 1039 gets increasingly complex with the number of CDN nodes and datacenter 1040 operators that are involved. In particular, privacy concerns prevent 1041 that this kind of data is shared across administrative domains. The 1042 ALTO Cost Calendar avoids these problems by presenting an abstracted 1043 view of time sensitive utilization maps through a dedicated ALTO 1044 service to allow ICPs a coherent scheduling of data transfers across 1045 administrative domains and time zones. 1047 Likewise, bandwidth Calendaring allows network operators to reserve 1048 resources in advance according to agreements with their customers, 1049 enabling them to transmit data with specified starting time and 1050 duration, for example, for a scheduled bulk data replication between 1051 data centers. Traditionally, this can be supported by a Network 1052 Management System operation such as path pre-establishment and 1053 activation on the agreed starting time. However, this does not 1054 provide efficient network usage since the established paths exclude 1055 the possibility of being used by other services even when they are 1056 not used for undertaking any service. 1058 An ALTO Cost calendar for TE metrics on transfer paths can support 1059 the scheduled bulk data replication with better efficiency since it 1060 can alleviate the processing burden on network elements. 1062 Cost calendars for these time-sensitive ALTO TE metrics need to 1063 consider the network topology and the dynamicity of the traffic. For 1064 example, a small topology with low density and low capacity that 1065 carries inpredictable, heavy and bursty traffic has few chances to 1066 exhibit stationary TE metric value patterns over large periods and 1067 would benefit to use the ALTO Calendar over smaller time slots. Some 1068 ALTO TE metric values, even aggregated over time may need to be 1069 updated at a frequency that would require doing ALTO requests at a 1070 pace that would be overload both the ALTO Client and the Server. 1071 Large high capacity topologies would benefit from Cost Calendars with 1072 a coarse time granularity for the filtered cost map service where as 1073 Calendars of finer time granularity for the Endpoint Cost Service 1074 would be better suited for small low density and capacity topologies. 1076 5.1.1. Applicable example transaction 1078 Assuming a Large high capacity topology, an applicable example 1079 transaction for this us case is provided by section 4.1.3. "Example 1080 transaction for a FCM with a "request-date" bandwidth Calendar". 1082 5.2. Applications with limited connectivity or access to datacenters 1084 Some applications are limited in their connectivity either in time or 1085 resources or both. For example applications running on devices in 1086 remote locations or in developing countries that need to synchronize 1087 their state with a data center periodically, in particular if 1088 sometimes there is no connection at all. Example applications are 1089 enterprise database update, remote learning, remote computation 1090 distributed on several data center endpoints. 1092 Wireless connections have a variable quality and may even be 1093 intermittent. On the other hand, the wireless network conditions 1094 have a rapid impact on applications while they can sometimes be 1095 predicted over a span of time. Non real time applications and time- 1096 insensitive data transfers such as client patching, archive syncing, 1097 etc. can benefit from careful scheduling. It is thus desirable to 1098 provide ALTO clients with routing costs to connection nodes (i.e. 1099 Application Endpoints) over different time periods. This would allow 1100 end systems using ALTO aware application clients to schedule their 1101 connections to application endpoints. 1103 Another challenge arises with applications using data and physical 1104 resources scattered around the world. For non-real time 1105 applications, the interaction with Endpoints can be orchestratrated 1106 and scheduled at the time slots corresponding to the best possible 1107 network conditions. For instance, resource Ra downloaded from 1108 Endpoint EPa at time t1, Resource Rb uploaded to EPb at time t2, some 1109 batch computation involving Ra and Rb done on EPc at time t3 and 1110 results R(A,B) downloaded to EPd and EPe at time t4. 1112 +-----+ +-----+ 1113 | EPa | | EPb | <----- Rb 1114 +-----+ +-----+ (t2=50) 1115 | +-------+ | 1116 Ra --------------> | EPc | | 1117 (time t1=10) | | | 1118 |t3=100 | <----------------- Rb 1119 +-------+ 1120 | \ 1121 | \ 1122 R(Ra,Rb) 1123 (t4=200) 1124 | \ 1125 | -------------------. 1126 V V 1127 +-----+ +-----+ 1128 | EPd | | EPe | 1129 +-----+ +-----+ 1131 5.2.1. Applicable example transaction 1133 An applicable example transaction for this use case is provided by 1134 section 4.2.3. "Example transaction for the ECS with a "periodic" 1135 routingcost Calendar". 1137 5.3. SDN Controller guided traffic scheduling with Calendars 1139 An ALTO Server can assist an SDN Controller by hosting abstracted 1140 network information that can be provided to SDN aware applications 1141 via an ALTO Client. 1143 Via the Northbound interface (NBI), applications may get QoE 1144 impacting information such as network provider preferences w.r.t. 1145 delay and bandwidth on the network paths. Such information may be 1146 provided via the ALTO Service. 1148 One key objective of an SDN controller is the ability to balance the 1149 application traffic whenever possible. Resources availability may 1150 often be predicted and strong incentives for applications to time 1151 shift their traffic may be given by network operators appropriately 1152 setting routing cost values at different time values, according to 1153 their policy on network utilization over time. 1155 To achieve this objective, the SDN controller can: 1157 1. get the network state information from its controlled network 1158 elements through its southbound API and derive an estimation of 1159 these values over given time frames 1161 2. abstract the network topology and end to end path costs and store 1162 them in an ALTO Server as Network Maps and Cost Calendars 1164 3. deliver these values to ALTO Clients linked to SDN applications, 1165 through the NBI. 1167 This way: 1169 o On one hand, the applications get the best possible QoE, as they 1170 can pick the best time for them to access one or more Endpoints or 1171 PIDs, 1173 o One the other hand, the SDN controller achieves load balancing and 1174 optimizes application traffic as it may guide the application 1175 traffic so as to better distribute the traffic over time. 1177 5.3.1. Applicable example transaction 1179 An applicable example transaction for this use case is provided by 1180 section 4.2.4. "Example transaction for the ECS with a calendar on 1181 both routingcost and latency". 1183 6. IANA Considerations 1185 Information for the ALTO Endpoint property registry maintained by the 1186 IANA and related to the new Endpoints supported by the acting ALTO 1187 server. These definitions will be formulated according to the syntax 1188 defined in Section on "ALTO Endpoint Property Registry" of [RFC7285] 1189 , 1191 Information for the ALTO Cost Type Registry maintained by the IANA 1192 and related to the new Cost Types supported by the acting ALTO 1193 server. These definitions will be formulated according to the syntax 1194 defined in Section on "ALTO Cost Type Registry" of [RFC7285], 1196 6.1. Information for IANA on proposed Cost Types 1198 When a new ALTO Cost Type is defined, accepted by the ALTO working 1199 group and requests for IANA registration MUST include the following 1200 information, detailed in Section 11.2: Identifier, Intended 1201 Semantics, Security Considerations. 1203 6.2. Information for IANA on proposed Endpoint Propeeries 1205 Likewise, an ALTO Endpoint Property Registry could serve the same 1206 purposes as the ALTO Cost Type registry. Application to IANA 1207 registration for Endpoint Properties would follow a similar process. 1209 7. Acknowledgements 1211 Thank you to Diego Lopez, He Peng and Haibin Song and the ALTO WG for 1212 fruitful discussions. 1214 8. References 1216 8.1. Normative References 1218 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1219 Requirement Levels", BCP 14, RFC 2119, 1220 DOI 10.17487/RFC2119, March 1997, 1221 . 1223 [RFC5693] Seedorf, J. and E. Burger, "Application-Layer Traffic 1224 Optimization (ALTO) Problem Statement", RFC 5693, 1225 DOI 10.17487/RFC5693, October 2009, 1226 . 1228 8.2. Informative References 1230 [draft-ietf-alto-multi-cost] 1231 S. Randriamasy, W. Roome, N. Schwan, , "Multi-Cost ALTO 1232 (work in progress), draft-ietf-alto-multi-cost", May 2015. 1234 [draft-wu-alto-te-metrics] 1235 Q. Wu, Y. Yang, Y. Lee, D. Dhody, S. Randriamasy, , "ALTO 1236 Traffic Engineering Cost Metrics (work in progress)", 1237 October 2014. 1239 [draft-yang-alto-topology] 1240 Y. Yang, , "ALTO Topology Considerations (work in 1241 progress)", July 2013. 1243 [ID-alto-protocol] 1244 R.Alimi, R. Penno, Y. Yang, Eds., "ALTO Protocol, RFC 1245 7285", September 2014. 1247 [RFC7285] R. Alimi, R. Yang, R. Penno, Eds., "ALTO Protocol", 1248 September 2014. 1250 [sdnrg] "Software Defined Network Research Group, 1251 http://trac.tools.ietf.org/group/irtf/trac/wiki/sdnrg". 1253 [slides-88-alto-5-topology] 1254 G. Bernstein, Y. Lee, Y. Yang, , , "ALTO Topology Service: 1255 Use Cases, Requirements and Framework (presentation slides 1256 IETF88 ALTO WG session), 1257 http://tools.ietf.org/agenda/88/slides/ 1258 slides-88-alto-5.pdf", November 2013. 1260 Authors' Addresses 1262 Sabine Randriamasy 1263 Nokia Bell Labs 1264 Route de Villejust 1265 NOZAY 91460 1266 FRANCE 1268 Email: Sabine.Randriamasy@nokia-bell-labs.com 1269 Richard Yang 1270 Yale University 1271 51 Prospect st 1272 New Haven, CT 06520 1273 USA 1275 Email: yry@cs.yale.edu 1277 Qin Wu 1278 Huawei 1279 101 Software Avenue, Yuhua District 1280 Nanjing, Jiangsu 210012 1281 China 1283 Email: sunseawq@huawei.com 1285 Lingli Deng 1286 China Mobile 1287 China 1289 Email: denglingli@chinamobile.com 1291 Nico Schwan 1292 Thales Deutschland 1294 Email: nico.schwan@thalesgroup.com