idnits 2.17.1 draft-ginsberg-isis-te-app-02.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 == Line 476 has weird spacing: '...pecific y ...' == Line 483 has weird spacing: '...pecific n ...' -- The document date (June 7, 2017) is 2505 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) ** Obsolete normative reference: RFC 5226 (Obsoleted by RFC 8126) ** Obsolete normative reference: RFC 7810 (Obsoleted by RFC 8570) Summary: 2 errors (**), 0 flaws (~~), 3 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Networking Working Group L. Ginsberg 3 Internet-Draft P. Psenak 4 Intended status: Standards Track Cisco Systems 5 Expires: December 9, 2017 S. Previdi 6 Individual 7 W. Henderickx 8 Nokia 9 June 7, 2017 11 IS-IS TE Attributes per application 12 draft-ginsberg-isis-te-app-02.txt 14 Abstract 16 Existing traffic engineering related link attribute advertisements 17 have been defined and are used in RSVP-TE deployments. In cases 18 where multiple applications wish to make use of these link attributes 19 the current advertisements do not support application specific values 20 for a given attribute nor do they support indication of which 21 applications are using the advertised value for a given link. 23 This draft introduces new link attribute advertisements which address 24 both of these shortcomings. It also discusses backwards 25 compatibility issues and how to minimize duplicate advertisements in 26 the presence of routers which do not support the extensions defined 27 in this document. 29 Requirements Language 31 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 32 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 33 document are to be interpreted as described in RFC 2119 [RFC2119]. 35 Status of This Memo 37 This Internet-Draft is submitted in full conformance with the 38 provisions of BCP 78 and BCP 79. 40 Internet-Drafts are working documents of the Internet Engineering 41 Task Force (IETF). Note that other groups may also distribute 42 working documents as Internet-Drafts. The list of current Internet- 43 Drafts is at http://datatracker.ietf.org/drafts/current/. 45 Internet-Drafts are draft documents valid for a maximum of six months 46 and may be updated, replaced, or obsoleted by other documents at any 47 time. It is inappropriate to use Internet-Drafts as reference 48 material or to cite them other than as "work in progress." 49 This Internet-Draft will expire on December 9, 2017. 51 Copyright Notice 53 Copyright (c) 2017 IETF Trust and the persons identified as the 54 document authors. All rights reserved. 56 This document is subject to BCP 78 and the IETF Trust's Legal 57 Provisions Relating to IETF Documents 58 (http://trustee.ietf.org/license-info) in effect on the date of 59 publication of this document. Please review these documents 60 carefully, as they describe your rights and restrictions with respect 61 to this document. Code Components extracted from this document must 62 include Simplified BSD License text as described in Section 4.e of 63 the Trust Legal Provisions and are provided without warranty as 64 described in the Simplified BSD License. 66 Table of Contents 68 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 69 2. Requirements Discussion . . . . . . . . . . . . . . . . . . . 3 70 3. Legacy Advertisements . . . . . . . . . . . . . . . . . . . . 4 71 3.1. Legacy sub-TLVs . . . . . . . . . . . . . . . . . . . . . 4 72 3.2. Legacy SRLG Advertisements . . . . . . . . . . . . . . . 5 73 4. Advertising Application Specific Link Attributes . . . . . . 5 74 4.1. Application Identifiers . . . . . . . . . . . . . . . . . 5 75 4.2. Application Specific Link Attributes sub-TLV . . . . . . 7 76 4.3. Application Specific SRLG TLV . . . . . . . . . . . . . . 8 77 5. Attribute Advertisements and Enablement . . . . . . . . . . . 9 78 6. Interoperability, Backwards Compatibility and Migration 79 Concerns . . . . . . . . . . . . . . . . . . . . . . . . . . 9 80 6.1. RSVP-TE only deployments . . . . . . . . . . . . . . . . 10 81 6.2. Multiple Applications: Common Attributes with RSVP-TE . 10 82 6.3. Multiple Applications: All Attributes Not Shared w RSVP- 83 TE . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 84 6.4. Deprecating legacy advertisements . . . . . . . . . . . . 10 85 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 86 8. Security Considerations . . . . . . . . . . . . . . . . . . . 12 87 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12 88 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 89 10.1. Normative References . . . . . . . . . . . . . . . . . . 12 90 10.2. Informative References . . . . . . . . . . . . . . . . . 13 91 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13 93 1. Introduction 95 Advertisement of link attributes by the Intermediate-System-to- 96 Intermediate-System (IS-IS) protocol in support of traffic 97 engineering (TE) was introduced by [RFC5305] and extended by 98 [RFC5307], [RFC6119], and [RFC7810]. Use of these extensions has 99 been associated with deployments supporting Traffic Engineering over 100 Multiprotocol Label Switching (MPLS) in the presence of Resource 101 Reservation Protocol (RSVP) - more succinctly referred to as RSVP-TE. 103 In recent years new applications have been introduced which have use 104 cases for many of the link attributes historically used by RSVP-TE. 105 Such applications include Segment Routing Traffic Engineering (SRTE) 106 and Loop Free Alternates (LFA). This has introduced ambiguity in 107 that if a deployment includes a mix of RSVP-TE support and SRTE 108 support (for example) it is not possible to unambiguously indicate 109 which advertisements are to be used by RSVP-TE and which 110 advertisements are to be used by SRTE. If the topologies are fully 111 congruent this may not be an issue, but any incongruence leads to 112 ambiguity. 114 An additional issue arises in cases where both applications are 115 supported on a link but the link attribute values associated with 116 each application differ. Current advertisements do not support 117 advertising application specific values for the same attribute on a 118 specific link. 120 This document defines extensions which address these issues. Also, 121 as evolution of use cases for link attributes can be expected to 122 continue in the years to come, this document defines a solution which 123 is easily extensible to the introduction of new applications and new 124 use cases. 126 2. Requirements Discussion 128 As stated previously, evolution of use cases for link attributes can 129 be expected to continue - so any discussion of existing use cases is 130 limited to requirements which are known at the time of this writing. 131 However, in order to determine the functionality required beyond what 132 already exists in IS-IS, it is only necessary to discuss use cases 133 which justify the key points identified in the introduction - which 134 are: 136 1. Support for indicating which applications are using the link 137 attribute advertisements on a link 139 2. Support for advertising application specific values for the same 140 attribute on a link 142 [RFC7855] discusses use cases/requirements for SR. Included among 143 these use cases is SRTE. If both RSVP-TE and SRTE are deployed in a 144 network, link attribute advertisements can be used by one or both of 145 these applications. As there is no requirement for the link 146 attributes advertised on a given link used by SRTE to be identical to 147 the link attributes advertised on that same link used by RSVP-TE, 148 there is a clear requirement to indicate independently which link 149 attribute advertisements are to be used by each application. 151 As the number of applications which may wish to utilize link 152 attributes may grow in the future, an additional requirement is that 153 the extensions defined allow the association of additional 154 applications to link attributes without altering the format of the 155 advertisements or introducing new backwards compatibility issues. 157 Finally, there may still be many cases where a single attribute value 158 can be shared among multiple applications, so the solution must 159 minimize advertising duplicate link/attribute pairs whenever 160 possible. 162 3. Legacy Advertisements 164 There are existing advertisements used in support of RSVP-TE. These 165 advertisements include sub-TLVs for TLVs 22, 23, 141, 222, and 223 166 and TLVs for SRLG advertisement. 168 3.1. Legacy sub-TLVs 170 Sub-TLVs for TLVs 22, 23, 141, 222, and 223 172 Code Point/Attribute Name 173 -------------------------- 174 3 Administrative group (color) 175 9 Maximum link bandwidth 176 10 Maximum reservable link bandwidth 177 11 Unreserved bandwidth 178 14 Extended Administrative Group 179 33 Unidirectional Link Delay 180 34 Min/Max Unidirectional Link Delay 181 35 Unidirectional Delay Variation 182 36 Unidirectional Link Loss 183 37 Unidirectional Residual Bandwidth 184 38 Unidirectional Available Bandwidth 185 39 Unidirectional Utilized Bandwidth 187 3.2. Legacy SRLG Advertisements 189 TLV 138 GMPLS-SRLG 190 Supports links identified by IPv4 addresses and 191 unnumbered links 193 TLV 139 IPv6 SRLG 194 Supports links identified by IPv6 addresses 196 Note that [RFC6119] prohibits the use of TLV 139 when it is possible 197 to use TLV 138. 199 4. Advertising Application Specific Link Attributes 201 Two new code points are defined in support of Application Specific 202 Link Attribute Advertisements: 204 1) Application Specific Link Attributes sub-TLV for TLVs 22, 23, 141, 205 222, and 223 207 2)Application Specific Shared Risk Link Group (SRLG) TLV 209 In support of these new advertisements, an application bit mask is 210 defined which identifies the application(s) associated with a given 211 advertisement. 213 The following sections define the format of these new advertisements. 215 4.1. Application Identifiers 217 Identification of the set of standard applications associated with 218 the link attribute advertisements utilizes a bit mask where the 219 definition of each bit is defined in a new IANA controlled registry. 220 There is also support for non-standard User Defined 221 Applications(UDAs) which may be optionally included. 223 This encoding is used by both the Application Specific Link 224 Attributes sub-TLV and the Application Specific SRLG TLV. 226 Standard Application Bit Mask Length/Flags: Non-zero (1 octet) 227 If this octet is 0 the entire sub-TLV/TLV in which it is 228 contained MUST be ignored. 230 0 1 2 3 4 5 6 7 231 +-+-+-+-+-+-+-+-+ 232 |U|L| SA-Length | 233 +-+-+-+-+-+-+-+-+ 235 U-flag: When set indicates the presence of a 236 UDA length/Bit Mask. 238 L-flag: Applications listed (both Standard and 239 User Defined) MUST use the legacy advertisements 240 for the corresponding link found in TLVs 22, 23, 241 141, 222, and 223 or TLV 138 or TLV 139 as appropriate. 243 SA-Length: Indicates the length in octets (0-63) of the Bit Mask 244 for Standard Applications in octets. The length MAY be 0 245 if the U-flag is set and there are no Standard 246 Applications being advertised. 248 Standard Application Bit Mask 249 This is omitted if SA-Length is 0. 251 (SA-Length * 8) bits 253 0 1 2 3 4 5 6 7 ... 254 +-+-+-+-+-+-+-+-+... 255 |R|S|F| ... 256 +-+-+-+-+-+-+-+-+... 258 R-bit: RSVP-TE 260 S-bit: Segment Routing Traffic Engineering 262 F-bit: Loop Free Alternate 264 If the U-flag is set then the following fields are 265 included: 267 User Defined Application Bit Mask Length 268 in octets: Non-zero (1 octet) 270 User Defined Application Bit Mask 272 (UDA Length * 8) bits 274 0 1 2 3 4 5 6 7 ... 275 +-+-+-+-+-+-+-+-+... 276 | ... 277 +-+-+-+-+-+-+-+-+... 279 Standard Application Bits are defined/sent starting with Bit 0. 280 Additional bit definitions that may be defined in the future SHOULD 281 be assigned in ascending bit order so as to minimize the number of 282 octets that will need to be transmitted. Undefined bits MUST be 283 transmitted as 0 and MUST be ignored on receipt. Bits that are NOT 284 transmitted MUST be treated as if they are set to 0 on receipt. 286 User Defined Application bits have no relationship to Standard 287 Application bits and are NOT managed by IANA or any other standards 288 body. It is recommended that bits are used starting with Bit 0 so as 289 to minimize the number of octets required to advertise all UDAs. 291 4.2. Application Specific Link Attributes sub-TLV 293 A new sub-TLV for TLVs 22, 23, 141, 222, and 223 is defined which 294 supports specification of the applications and application specific 295 attribute values. 297 Type: 15 (suggested value - to be assigned by IANA) 298 Length: Variable (1 octet) 299 Value: 301 Application Bit Mask (as defined in Section 3.1) 303 Link Attribute sub-sub-TLVs - format matches the 304 existing formats defined in [RFC5305] and [RFC7810] 306 When the L-flag is set in the Application Identifiers, all of the 307 applications specified in the bit mask MUST use the link attribute 308 sub-TLV advertisements listed in Section 3.1 for the corresponding 309 link. Application specific link attribute sub-sub-TLVs for the 310 corresponding link attributes MUST NOT be advertised for the set of 311 applications specified in the Standard/User Application Bit Masks and 312 all such advertisements MUST be ignored on receipt. 314 Multiple sub-TLVs for the same link MAY be advertised. When multiple 315 sub-TLVs for the same link are advertised, they SHOULD advertise non- 316 conflicting application/attribute pairs. A conflict exists when the 317 same application is associated with two different values of the same 318 link attribute for a given link. In cases where conflicting values 319 for the same application/attribute/link are advertised all the 320 conflicting values MUST be ignored. 322 For a given application, the setting of the L-flag MUST be the same 323 in all sub-TLVs for a given link. In cases where this constraint is 324 violated, the L-flag MUST be considered set for this application. 326 A new registry of sub-sub-TLVs is to be created by IANA which defines 327 the link attribute sub-sub-TLV code points. A sub-sub-TLV is defined 328 for each of the existing sub-TLVs listed in Section 3.1. Format of 329 the sub-sub-TLVs matches the format of the corresponding legacy sub- 330 TLV and IANA is requested to assign the legacy sub-TLV identifer to 331 the corresponding sub-sub-TLV. 333 4.3. Application Specific SRLG TLV 335 A new TLV is defined to advertise application specific SRLGs for a 336 given link. Although similar in functionality to TLV 138 (defined by 337 [RFC5307]) and TLV 139 (defined by [RFC6119], a single TLV provides 338 support for IPv4, IPv6, and unnumbered identifiers for a link. 339 Unlike TLVs 138/139, it utilizes sub-TLVs to encode the link 340 identifiers in order to provide the flexible formatting required to 341 support multiple link identifier types. 343 Type: 238 (Suggested value - to be assigned by IANA) 344 Length: Number of octets in the value field (1 octet) 345 Value: 346 Neighbor System-ID + pseudo-node ID (7 octets) 347 Application Bit Mask (as defined in Section 3.1) 348 Length of sub-TLVs (1 octet) 349 Link Identifier sub-TLVs (variable) 350 0 or more SRLG Values (Each value is 4 octets) 352 The following Link Identifier sub-TLVs are defined. The type 353 values are suggested and will be assigned by IANA - but as 354 the formats are identical to existing sub-TLVs defined for 355 TLVs 22, 23, 141, 222, and 223 the use of the suggested sub-TLV 356 types is strongly encouraged. 358 Type Description 359 4 Link Local/Remote Identifiers (see [RFC5307]) 360 6 IPv4 interface address (see [RFC5305]) 361 8 IPv4 neighbor address (see [RFC5305]) 362 12 IPv6 Interface Address (see [RFC6119]) 363 13 IPv6 Neighbor Address (see [RFC6119]) 365 At least one set of link identifiers (IPv4, IPv6, or unnumbered) MUST 366 be present. TLVs which do not meet this requirement MUST be ignored. 368 Multiple TLVs for the same link MAY be advertised. 370 When the L-flag is set in the Application Identifiers, SRLG values 371 MUST NOT be included in the TLV. Any SRLG values which are 372 advertised MUST be ignored. Based on the link identifiers advertised 373 the corresponding legacy TLV (see Section 3.2) can be identified and 374 the SRLG values advertised in the legacy TLV MUST be used by the set 375 of applications specified in the Application Bit Mask. 377 For a given application, the setting of the L-flag MUST be the same 378 in all TLVs for a given link. In cases where this constraint is 379 violated, the L-flag MUST be considered set for this application. 381 5. Attribute Advertisements and Enablement 383 This document defines extensions to support the advertisement of 384 application specific link attributes. The presence or absence of 385 link attribute advertisements for a given application on a link does 386 NOT indicate the state of enablement of that application on that 387 link. Enablement of an application on a link is controlled by other 388 means. 390 For some applications, the concept of enablement is implicit. For 391 example, SRTE implicitly is enabled on all links which are part of 392 the Segment Routing enabled topology. Advertisement of link 393 attributes supports constraints which may be applied when specifying 394 an explicit path through that topology. 396 For other applications enablement is controlled by local 397 configuration. For example, use of a link as an LFA can be 398 controlled by local enablement/disablement and/or the use of 399 administrative tags. 401 It is an application specific policy as to whether a given link can 402 be used by that application even in the abscence of any application 403 specififc link attributes. 405 6. Interoperability, Backwards Compatibility and Migration Concerns 407 Existing deployments of RSVP-TE utilize the legacy advertisements 408 listed in Section 3. Routers which do not support the extensions 409 defined in this document will only process legacy advertisements and 410 are likely to infer that RSVP-TE is enabled on the links for which 411 legacy advertisements exist. It is expected that deployments using 412 the legacy advertisements will persist for a significant period of 413 time - therefore deployments using the extensions defined in this 414 document must be able to co-exist with use of the legacy 415 advertisements by routers which do not support the extensions defined 416 in this document. The following sub-sections discuss 417 interoperability and backwards compatibility concerns for a number of 418 deployment scenarios. 420 Note that in all cases the defined strategy can be employed on a per 421 link basis. 423 6.1. RSVP-TE only deployments 425 In deployments where RSVP-TE is the only application utilizing link 426 attribute advertisements, use of the the legacy advertisements can 427 continue without change. 429 6.2. Multiple Applications: Common Attributes with RSVP-TE 431 In cases where multiple applications are utilizing a given link, one 432 of the applications is RSVP-TE, and all link attributes for a given 433 link are common to the set of applications utilizing that link, 434 interoperability is achieved by using legacy advertisements and 435 sending application specific advertisements with L-bit set and no 436 link attribute values. This avoids duplication of link attribute 437 advertisements. 439 6.3. Multiple Applications: All Attributes Not Shared w RSVP-TE 441 In cases where one or more applications other than RSVP-TE are 442 utilizing a given link and one or more link attribute values are NOT 443 shared with RSVP-TE, it is necessary to use application specific 444 advertisements as defined in this document. Attributes for 445 applications other than RSVP-TE MUST be advertised using application 446 specific advertisements which have the L-bit clear. In cases where 447 some link attributes are shared with RSVP-TE, this requires duplicate 448 advertisements for those attributes. 450 The discussion in this section applies to cases where RSVP-TE is NOT 451 using any advertised attributes on a link and to cases where RSVP-TE 452 is using some link attribute advertisements on the link but some link 453 attributes cannot be shared with RSVP-TE. 455 6.4. Deprecating legacy advertisements 457 The extensions defined in this document support RSVP-TE as one of the 458 supported applications - so a long term goal for deployments would be 459 to deprecate use of the legacy advertisements in support of RSVP-TE. 460 This can be done in the following step-wise manner: 462 1)Upgrade all routers to support extensions in this document 464 2)Readvertise all legacy link attributes using application specific 465 advertisements with L-bit clear and R-bit set. 467 3)Remove legacy advertisements 469 7. IANA Considerations 471 This document defines a new sub-TLV for TLVs 22, 23, 141, 222, and 472 223. 474 Type Description 22 23 141 222 223 475 ---- --------------------- --- --- --- --- --- 476 15 Application Specific y y y y y 477 Link Attributes 479 This document defines one new TLV: 481 Type Description IIH SNP LSP Purge 482 ---- --------------------- --- --- --- ----- 483 238 Application Specific n n y n 484 SRLG 486 This document requests a new IANA registry be created to control the 487 assignment of sub-sub-TLV codepoints for the Application Specific 488 Link Attributes sub-TLV. The suggested name of the new registry is 489 "sub-sub-TLV code points for application link attributes". The 490 registration procedure is "Expert Review" as defined in [RFC5226]. 491 The following assignments are made by this document: 493 Type Description 494 --------------------------------------------------------- 495 3 Administrative group (color) 496 9 Maximum link bandwidth 497 10 Maximum reservable link bandwidth 498 11 Unreserved bandwidth 499 14 Extended Administrative Group 500 33 Unidirectional Link Delay 501 34 Min/Max Unidirectional Link Delay 502 35 Unidirectional Delay Variation 503 36 Unidirectional Link Loss 504 37 Unidirectional Residual Bandwidth 505 38 Unidirectional Available Bandwidth 506 39 Unidirectional Utilized Bandwidth 508 This document requests a new IANA registry be created to control the 509 assignment of application bit identifiers. The suggested name of the 510 new registry is "Link Attribute Applications". The registration 511 procedure is "Expert Review" as defined in [RFC5226]. The following 512 assignments are made by this document: 514 Bit # Name 515 --------------------------------------------------------- 516 0 RSVP-TE (R-bit) 517 1 Segment Routing Traffic Engineering (S-bit) 518 2 Loop Free Alternate (F-bit) 520 This document requests a new IANA registry be created to control the 521 assignment of sub-TLV types for the application specific SRLG TLV. 522 The suggested name of the new registry is "Sub-TLVs for TLV 238". 523 The registration procedure is "Expert Review" as defined in 524 [RFC5226]. The following assignments are made by this document: 526 Value Description 527 --------------------------------------------------------- 528 4 Link Local/Remote Identifiers (see [RFC5307]) 529 6 IPv4 interface address (see [RFC5305]) 530 8 IPv4 neighbor address (see [RFC5305]) 531 12 IPv6 Interface Address (see [RFC6119]) 532 13 IPv6 Neighbor Address (see [RFC6119]) 534 8. Security Considerations 536 Security concerns for IS-IS are addressed in [ISO10589, [RFC5304], 537 and [RFC5310]. 539 9. Acknowledgements 541 The authors would like to thank John Drake and Acee Lindem for their 542 careful review and content suggestions. 544 10. References 546 10.1. Normative References 548 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 549 Requirement Levels", BCP 14, RFC 2119, 550 DOI 10.17487/RFC2119, March 1997, 551 . 553 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an 554 IANA Considerations Section in RFCs", BCP 26, RFC 5226, 555 DOI 10.17487/RFC5226, May 2008, 556 . 558 [RFC5304] Li, T. and R. Atkinson, "IS-IS Cryptographic 559 Authentication", RFC 5304, DOI 10.17487/RFC5304, October 560 2008, . 562 [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic 563 Engineering", RFC 5305, DOI 10.17487/RFC5305, October 564 2008, . 566 [RFC5307] Kompella, K., Ed. and Y. Rekhter, Ed., "IS-IS Extensions 567 in Support of Generalized Multi-Protocol Label Switching 568 (GMPLS)", RFC 5307, DOI 10.17487/RFC5307, October 2008, 569 . 571 [RFC5310] Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R., 572 and M. Fanto, "IS-IS Generic Cryptographic 573 Authentication", RFC 5310, DOI 10.17487/RFC5310, February 574 2009, . 576 [RFC6119] Harrison, J., Berger, J., and M. Bartlett, "IPv6 Traffic 577 Engineering in IS-IS", RFC 6119, DOI 10.17487/RFC6119, 578 February 2011, . 580 [RFC7810] Previdi, S., Ed., Giacalone, S., Ward, D., Drake, J., and 581 Q. Wu, "IS-IS Traffic Engineering (TE) Metric Extensions", 582 RFC 7810, DOI 10.17487/RFC7810, May 2016, 583 . 585 10.2. Informative References 587 [RFC7855] Previdi, S., Ed., Filsfils, C., Ed., Decraene, B., 588 Litkowski, S., Horneffer, M., and R. Shakir, "Source 589 Packet Routing in Networking (SPRING) Problem Statement 590 and Requirements", RFC 7855, DOI 10.17487/RFC7855, May 591 2016, . 593 Authors' Addresses 595 Les Ginsberg 596 Cisco Systems 597 821 Alder Drive 598 Milpitas, CA 95035 599 USA 601 Email: ginsberg@cisco.com 602 Peter Psenak 603 Cisco Systems 604 Apollo Business Center Mlynske nivy 43 605 Bratislava 821 09 606 Slovakia 608 Email: ppsenak@cisco.com 610 Stefano Previdi 611 Individual 613 Email: stefano@previdi.net 615 Wim Henderickx 616 Nokia 617 Copernicuslaan 50 618 Antwerp 2018 94089 619 Belgium 621 Email: wim.henderickx@nokia.com