idnits 2.17.1 draft-ginsberg-isis-te-app-01.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 434 has weird spacing: '...pecific y ...' == Line 441 has weird spacing: '...pecific n ...' -- The document date (May 31, 2017) is 2521 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 S. Previdi 5 Expires: December 2, 2017 Cisco Systems 6 W. Henderickx 7 Nokia 8 May 31, 2017 10 IS-IS TE Attributes per application 11 draft-ginsberg-isis-te-app-01.txt 13 Abstract 15 Existing traffic engineering related link attribute advertisements 16 have been defined and are used in RSVP-TE deployments. In cases 17 where multiple applications wish to make use of these link attributes 18 the current advertisements do not support application specific values 19 for a given attribute nor do they support indication of which 20 applications are using the advertised value for a given link. 22 This draft introduces new link attribute advertisements which address 23 both of these shortcomings. It also discusses backwards 24 compatibility issues and how to minimize duplicate advertisements in 25 the presence of routers which do not support the extensions defined 26 in this document. 28 Requirements Language 30 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 31 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 32 document are to be interpreted as described in RFC 2119 [RFC2119]. 34 Status of This Memo 36 This Internet-Draft is submitted in full conformance with the 37 provisions of BCP 78 and BCP 79. 39 Internet-Drafts are working documents of the Internet Engineering 40 Task Force (IETF). Note that other groups may also distribute 41 working documents as Internet-Drafts. The list of current Internet- 42 Drafts is at http://datatracker.ietf.org/drafts/current/. 44 Internet-Drafts are draft documents valid for a maximum of six months 45 and may be updated, replaced, or obsoleted by other documents at any 46 time. It is inappropriate to use Internet-Drafts as reference 47 material or to cite them other than as "work in progress." 48 This Internet-Draft will expire on December 2, 2017. 50 Copyright Notice 52 Copyright (c) 2017 IETF Trust and the persons identified as the 53 document authors. All rights reserved. 55 This document is subject to BCP 78 and the IETF Trust's Legal 56 Provisions Relating to IETF Documents 57 (http://trustee.ietf.org/license-info) in effect on the date of 58 publication of this document. Please review these documents 59 carefully, as they describe your rights and restrictions with respect 60 to this document. Code Components extracted from this document must 61 include Simplified BSD License text as described in Section 4.e of 62 the Trust Legal Provisions and are provided without warranty as 63 described in the Simplified BSD License. 65 Table of Contents 67 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 68 2. Requirements Discussion . . . . . . . . . . . . . . . . . . . 3 69 3. Legacy Advertisements . . . . . . . . . . . . . . . . . . . . 4 70 3.1. Legacy sub-TLVs . . . . . . . . . . . . . . . . . . . . . 4 71 3.2. Legacy SRLG Advertisements . . . . . . . . . . . . . . . 5 72 4. Advertising Application Specific Link Attributes . . . . . . 5 73 4.1. Application Bit Mask . . . . . . . . . . . . . . . . . . 6 74 4.2. Application Specific Link Attributes sub-TLV . . . . . . 7 75 4.3. Application Specific SRLG TLV . . . . . . . . . . . . . . 8 76 5. Interoperability, Backwards Compatibility and Migration 77 Concerns . . . . . . . . . . . . . . . . . . . . . . . . . . 9 78 5.1. RSVP-TE only deployments . . . . . . . . . . . . . . . . 9 79 5.2. Multiple Applications: Common Attributes with RSVP-TE . 9 80 5.3. Multiple Applications: All Attributes Not Shared w RSVP- 81 TE . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 82 5.4. Deprecating legacy advertisements . . . . . . . . . . . . 10 83 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 84 7. Security Considerations . . . . . . . . . . . . . . . . . . . 12 85 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12 86 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 87 9.1. Normative References . . . . . . . . . . . . . . . . . . 12 88 9.2. Informative References . . . . . . . . . . . . . . . . . 13 89 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13 91 1. Introduction 93 Advertisement of link attributes by the Intermediate-System-to- 94 Intermediate-System (IS-IS) protocol in support of traffic 95 engineering (TE) was introduced by [RFC5305] and extended by 97 [RFC5307], [RFC6119], and [RFC7810]. Use of these extensions has 98 been associated with deployments supporting Traffic Engineering over 99 Multiprotocol Label Switching (MPLS) in the presence of Resource 100 Reservation Protocol (RSVP) - more succinctly referred to as RSVP-TE. 101 Although implementations vary in their exact interpretation, it is 102 fair to say that the presence of any of the link attribute 103 advertisements currently defined (excluding link identifier 104 advertisements) are used by many implementations to imply the use of 105 that link by RSVP-TE. 107 In recent years new applications have been introduced which have use 108 cases for many of the link attributes historically used by RSVP-TE. 109 Such applications include Segment Routing Traffic Engineering (SR-TE) 110 and Loop Free Alternates (LFA). This has introduced ambiguity in 111 that if a deployment includes a mix of RSVP-TE support and SR-TE 112 support (for example) it is not possible to unambiguously indicate 113 which advertisements indicate support for/use by RSVP-TE and which 114 advertisements indicate support for/use by SR-TE. If the topologies 115 are fully congruent this may not be an issue, but any incongruence 116 leads to ambiguity. 118 An additional issue arises in cases where both applications are 119 supported on a link but the link attribute values associated with 120 each application differ. Current advertisements do not support 121 advertising application specific values for the same attribute on a 122 specific link. 124 This document defines extensions which address these issues. Also, 125 as evolution of use cases for link attributes can be expected to 126 continue in the years to come, this document defines a solution which 127 is easily extensible to the introduction of new applications and new 128 use cases. 130 2. Requirements Discussion 132 As stated previously, evolution of use cases for link attributes can 133 be expected to continue - so any discussion of existing use cases is 134 limited to requirements which are known at the time of this writing. 135 However, in order to determine the functionality required beyond what 136 already exists in IS-IS, it is only necessary to discuss use cases 137 which justify the key points identified in the introduction - which 138 are: 140 1. Support for indicating which applications are using the link 141 attribute advertisements on a link 143 2. Support for advertising application specific values for the same 144 attribute on a link 146 [RFC7855] discusses use cases/requirements for SR. Included among 147 these use cases is SR-TE. If both RSVP-TE and SR-TE are deployed in 148 a network, links can be used by one or both of these applications. 149 As there is no requirement for the topology supported for SR-TE to be 150 congruent to the topology supported for RSVP-TE, there is a clear 151 requirement to indicate independently which applications are 152 associated with a given link. 154 If both RSVP-TE and SR-TE are enabled on a given link, it is also 155 possible that an attribute value such as Maximum Bandwidth to be 156 utilized by SR-TE may be different than/disjoint from the Maximum 157 Bandwidth to be utilized by RSVP-TE. This leads to the requirement 158 that the solution support the advertisement of unique values for a 159 given link/attribute/application. 161 As the number of applications which may wish to utilize link 162 attributes may grow in the future, an additional requirement is that 163 the extensions defined allow the association of additional 164 applications to link attributes without altering the format of the 165 advertisements or introducing new backwards compatibility issues. 167 Finally, there may still be many cases where a single attribute value 168 can be shared among multiple applications, so the solution must 169 minimize advertising duplicate link/attribute pairs whenever 170 possible. 172 3. Legacy Advertisements 174 There are existing advertisements used in support of RSVP-TE. These 175 advertisements include sub-TLVs for TLVs 22, 23, 141, 222, and 223 176 and TLVs for SRLG advertisement. 178 3.1. Legacy sub-TLVs 179 Sub-TLVs for TLVs 22, 23, 141, 222, and 223 181 Code Point/Attribute Name 182 -------------------------- 183 3 Administrative group (color) 184 9 Maximum link bandwidth 185 10 Maximum reservable link bandwidth 186 11 Unreserved bandwidth 187 14 Extended Administrative Group 188 33 Unidirectional Link Delay 189 34 Min/Max Unidirectional Link Delay 190 35 Unidirectional Delay Variation 191 36 Unidirectional Link Loss 192 37 Unidirectional Residual Bandwidth 193 38 Unidirectional Available Bandwidth 194 39 Unidirectional Utilized Bandwidth 196 3.2. Legacy SRLG Advertisements 198 TLV 138 GMPLS-SRLG 199 Supports links identified by IPv4 addresses and 200 unnumbered links 202 TLV 139 IPv6 SRLG 203 Supports links identified by IPv6 addresses 205 Note that [RFC6119] prohibits the use of TLV 139 when it is possible 206 to use TLV 138. 208 4. Advertising Application Specific Link Attributes 210 Two new code points are defined in support of Application Specific 211 Link Attribute Advertisements: 213 1) Application Specific Link Attributes sub-TLV for TLVs 22, 23, 141, 214 222, and 223 216 2)Application Specific Shared Risk Link Group (SRLG) TLV 218 In support of these new advertisements, an application bit mask is 219 defined which identifies the application(s) associated with a given 220 advertisement. 222 The following sections define the format of these new advertisements. 224 4.1. Application Bit Mask 226 Identification of the set of applications associated with the link 227 attribute advertisements utilizes a bit mask where the definition of 228 each bit is defined in a new IANA controlled registry. This encoding 229 is used by both the Application Specific Link Attributes sub-TLV and 230 the Application Specific SRLG TLV. 232 Bit Mask Length: Non-zero (1 octet) 233 Application Bit Mask: Size is (Bit Mask Length+7)/8 234 The following bits are assigned/reserved: 236 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 237 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 238 |L|R|S|F| | UDA Use | 239 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 241 L-bit: Applications listed MUST use the legacy 242 advertisements for the corresponding link 243 found in TLVs 22, 23, 141, 222, and 223 or 244 TLV 138 or TLV 139 as appropriate. 246 R-bit: RSVP-TE 248 S-bit: Segment Routing Traffic Engineering 250 F-bit: Loop Free Alternate 252 UDA Use: These bits are reserved for User Defined 253 Application (UDA) use. These bits MUST NOT be 254 assigned by IANA for any standards based use. 256 Bits are defined/sent starting with Bit 0. Additional bit 257 definitions that may be defined in the future SHOULD be assigned in 258 ascending bit order so as to minimize the number of bits that will 259 need to be transmitted. Undefined bits MUST be transmitted as 0 and 260 MUST be ignored on receipt. Bits that are NOT transmitted MUST be 261 treated as if they are set to 0 on receipt. 263 The second octet is reserved for local use by proprietary and/or 264 experimental applications. These bits MUST NOT be assigned by IANA 265 for any standards based use. IANA owns the assignment of bits 0 - 7 266 and bits 16 and greater. 268 Note that the octet associated with UDA Use need only be transmitted 269 if any of the following conditions is met: 271 o One of the UDA bits is set 273 o Bit 16 or greater is set 275 4.2. Application Specific Link Attributes sub-TLV 277 A new sub-TLV for TLVs 22, 23, 141, 222, and 223 is defined which 278 supports specification of the applications and application specific 279 attribute values. 281 Type: 15 (suggested value - to be assigned by IANA) 282 Length: Variable (1 octet) 283 Value: 285 Application Bit Mask (as defined in Section 3.1) 287 Link Attribute sub-sub-TLVs - format matches the 288 existing formats defined in [RFC5305] and [RFC7810] 290 When the L-bit is set in the Application Bit Mask, all of the 291 applications specified in the bit mask MUST use the link attribute 292 sub-TLV advertisements listed in Section 3.1 for the corresponding 293 link. Application specific link attribute sub-sub-TLVs for the 294 corresponding link attributes MUST NOT be advertised for the set of 295 applications specified in the Application Bit Mask and all such 296 advertisements MUST be ignored on receipt. 298 Multiple sub-TLVs for the same link MAY be advertised. When multiple 299 sub-TLVs for the same link are advertised, they SHOULD advertise non- 300 conflicting application/attribute pairs. In cases where there are 301 multiple sub-TLVs for the same link and there is a conflict in the 302 attribute information advertised the behavior of the receiver is 303 undefined. 305 For a given application, the setting of the L-bit MUST be the same in 306 all sub-TLVs for a given link. In cases where this constraint is 307 violated, the L-bit MUST be considered set for this application. 309 A new registry of sub-sub-TLVs is to be created by IANA which defines 310 the link attribute sub-sub-TLV code points. A sub-sub-TLV is defined 311 for each of the existing sub-TLVs listed in Section 3.1. Format of 312 the sub-sub-TLVs matches the format of the corresponding legacy sub- 313 TLV and IANA is requested to assign the legacy sub-TLV identifer to 314 the corresponding sub-sub-TLV. 316 4.3. Application Specific SRLG TLV 318 A new TLV is defined to advertise application specific SRLGs for a 319 given link. Although similar in functionality to TLV 138 (defined by 320 [RFC5307]) and TLV 139 (defined by [RFC6119], a single TLV provides 321 support for IPv4, IPv6, and unnumbered identifiers for a link. 322 Unlike TLVs 138/139, it utilizes sub-TLVs to encode the link 323 identifiers in order to provide the flexible formatting required to 324 support multiple link identifier types. 326 Type: 238 (Suggested value - to be assigned by IANA) 327 Length: Number of octets in the value field (1 octet) 328 Value: 329 Neighbor System-ID + pseudo-node ID (7 octets) 330 Application Bit Mask (as defined in Section 3.1) 331 Length of sub-TLVs (1 octet) 332 Link Identifier sub-TLVs (variable) 333 0 or more SRLG Values (Each value is 4 octets) 335 The following Link Identifier sub-TLVs are defined. The type 336 values are suggested and will be assigned by IANA - but as 337 the formats are identical to existing sub-TLVs defined for 338 TLVs 22, 23, 141, 222, and 223 the use of the suggested sub-TLV 339 types is strongly encouraged. 341 Type Description 342 4 Link Local/Remote Identifiers (see [RFC5307]) 343 6 IPv4 interface address (see [RFC5305]) 344 8 IPv4 neighbor address (see [RFC5305]) 345 12 IPv6 Interface Address (see [RFC6119]) 346 13 IPv6 Neighbor Address (see [RFC6119]) 348 At least one set of link identifiers (IPv4, IPv6, or unnumbered) MUST 349 be present. TLVs which do not meet this requirement MUST be ignored. 351 Multiple TLVs for the same link MAY be advertised. 353 When the L-bit is set in the Application Bit Mask, SRLG values MUST 354 NOT be included in the TLV. Any SRLG values which are advertised 355 MUST be ignored. Based on the link identifiers advertised the 356 corresponding legacy TLV (see Section 3.2) can be identified and the 357 SRLG values advertised in the legacy TLV MUST be used by the set of 358 applications specified in the Application Bit Mask. 360 For a given application, the setting of the L-bit MUST be the same in 361 all TLVs for a given link. In cases where this constraint is 362 violated, the L-bit MUST be considered set for this application. 364 5. Interoperability, Backwards Compatibility and Migration Concerns 366 Existing deployments of RSVP-TE utilize the legacy advertisements 367 listed in Section 3. Routers which do not support the extensions 368 defined in this document will only process legacy advertisements and 369 are likely to infer that RSVP-TE is enabled on the links for which 370 legacy advertisements exist. It is expected that deployments using 371 the legacy advertisements will persist for a significant period of 372 time - therefore deployments using the extensions defined in this 373 document must be able to co-exist with use of the legacy 374 advertisements by routers which do not support the extensions defined 375 in this document. The following sub-sections discuss 376 interoperability and backwards compatibility concerns for a number of 377 deployment scenarios. 379 Note that in all cases the defined strategy can be employed on a per 380 link basis. 382 5.1. RSVP-TE only deployments 384 In deployments where RSVP-TE is the only application utilizing link 385 attribute advertisements, use of the the legacy advertisements can 386 continue without change. 388 5.2. Multiple Applications: Common Attributes with RSVP-TE 390 In cases where multiple applications are utilizing a given link, one 391 of the applications is RSVP-TE, and all link attributes for a given 392 link are common to the set of applications utilizing that link, 393 interoperability is achieved by using legacy advertisements and 394 sending application specific advertisements with L-bit set and no 395 link attribute values. This avoids duplication of link attribute 396 advertisements. 398 5.3. Multiple Applications: All Attributes Not Shared w RSVP-TE 400 In cases where one or more applications other than RSVP-TE are 401 utilizing a given link and one or more link attribute values are NOT 402 shared with RSVP-TE, it is necessary to use application specific 403 advertisements as defined in this document. Attributes for 404 applications other than RSVP-TE MUST be advertised using application 405 specific advertisements which have the L-bit clear. In cases where 406 some link attributes are shared with RSVP-TE, this requires duplicate 407 advertisements for those attributes. 409 The discussion in this section applies to cases where RSVP-TE is NOT 410 enabled on a link and to cases where RSVP-TE is enabled on the link 411 but some link attributes cannot be shared with RSVP-TE. 413 5.4. Deprecating legacy advertisements 415 The extensions defined in this document support RSVP-TE as one of the 416 supported applications - so a long term goal for deployments would be 417 to deprecate use of the legacy advertisements in support of RSVP-TE. 418 This can be done in the following step-wise manner: 420 1)Upgrade all routers to support extensions in this document 422 2)Readvertise all legacy link attributes using application specific 423 advertisements with L-bit clear and R-bit set. 425 3)Remove legacy advertisements 427 6. IANA Considerations 429 This document defines a new sub-TLV for TLVs 22, 23, 141, 222, and 430 223. 432 Type Description 22 23 141 222 223 433 ---- --------------------- --- --- --- --- --- 434 15 Application Specific y y y y y 435 Link Attributes 437 This document defines one new TLV: 439 Type Description IIH SNP LSP Purge 440 ---- --------------------- --- --- --- ----- 441 238 Application Specific n n y n 442 SRLG 444 This document requests a new IANA registry be created to control the 445 assignment of sub-sub-TLV codepoints for the Application Specific 446 Link Attributes sub-TLV. The suggested name of the new registry is 447 "sub-sub-TLV code points for application link attributes". The 448 registration procedure is "Expert Review" as defined in [RFC5226]. 449 The following assignments are made by this document: 451 Type Description 452 --------------------------------------------------------- 453 3 Administrative group (color) 454 9 Maximum link bandwidth 455 10 Maximum reservable link bandwidth 456 11 Unreserved bandwidth 457 14 Extended Administrative Group 458 33 Unidirectional Link Delay 459 34 Min/Max Unidirectional Link Delay 460 35 Unidirectional Delay Variation 461 36 Unidirectional Link Loss 462 37 Unidirectional Residual Bandwidth 463 38 Unidirectional Available Bandwidth 464 39 Unidirectional Utilized Bandwidth 466 This document requests a new IANA registry be created to control the 467 assignment of application bit identifiers. The suggested name of the 468 new registry is "Link Attribute Applications". The registration 469 procedure is "Expert Review" as defined in [RFC5226]. The following 470 assignments are made by this document: 472 Bit # Name 473 --------------------------------------------------------- 474 0 Legacy Attributes (L-bit) 475 1 RSVP-TE (R-bit) 476 2 Segment Routing Traffic Engineering (S-bit) 477 3 Loop Free Alternate (F-bit) 478 4-7 Unassigned 479 8-15 Reserved for User Defined Application Use 481 This document requests a new IANA registry be created to control the 482 assignment of sub-TLV types for the application specific SRLG TLV. 483 The suggested name of the new registry is "Sub-TLVs for TLV 238". 484 The registration procedure is "Expert Review" as defined in 485 [RFC5226]. The following assignments are made by this document: 487 Value Description 488 --------------------------------------------------------- 489 4 Link Local/Remote Identifiers (see [RFC5307]) 490 6 IPv4 interface address (see [RFC5305]) 491 8 IPv4 neighbor address (see [RFC5305]) 492 12 IPv6 Interface Address (see [RFC6119]) 493 13 IPv6 Neighbor Address (see [RFC6119]) 495 7. Security Considerations 497 Security concerns for IS-IS are addressed in [ISO10589, [RFC5304], 498 and [RFC5310]. 500 8. Acknowledgements 502 The authors would like to thank John Drake and Acee Lindem for their 503 careful review and content suggestions. 505 9. References 507 9.1. Normative References 509 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 510 Requirement Levels", BCP 14, RFC 2119, 511 DOI 10.17487/RFC2119, March 1997, 512 . 514 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an 515 IANA Considerations Section in RFCs", BCP 26, RFC 5226, 516 DOI 10.17487/RFC5226, May 2008, 517 . 519 [RFC5304] Li, T. and R. Atkinson, "IS-IS Cryptographic 520 Authentication", RFC 5304, DOI 10.17487/RFC5304, October 521 2008, . 523 [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic 524 Engineering", RFC 5305, DOI 10.17487/RFC5305, October 525 2008, . 527 [RFC5307] Kompella, K., Ed. and Y. Rekhter, Ed., "IS-IS Extensions 528 in Support of Generalized Multi-Protocol Label Switching 529 (GMPLS)", RFC 5307, DOI 10.17487/RFC5307, October 2008, 530 . 532 [RFC5310] Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R., 533 and M. Fanto, "IS-IS Generic Cryptographic 534 Authentication", RFC 5310, DOI 10.17487/RFC5310, February 535 2009, . 537 [RFC6119] Harrison, J., Berger, J., and M. Bartlett, "IPv6 Traffic 538 Engineering in IS-IS", RFC 6119, DOI 10.17487/RFC6119, 539 February 2011, . 541 [RFC7810] Previdi, S., Ed., Giacalone, S., Ward, D., Drake, J., and 542 Q. Wu, "IS-IS Traffic Engineering (TE) Metric Extensions", 543 RFC 7810, DOI 10.17487/RFC7810, May 2016, 544 . 546 9.2. Informative References 548 [RFC7855] Previdi, S., Ed., Filsfils, C., Ed., Decraene, B., 549 Litkowski, S., Horneffer, M., and R. Shakir, "Source 550 Packet Routing in Networking (SPRING) Problem Statement 551 and Requirements", RFC 7855, DOI 10.17487/RFC7855, May 552 2016, . 554 Authors' Addresses 556 Les Ginsberg 557 Cisco Systems 558 821 Alder Drive 559 Milpitas, CA 95035 560 USA 562 Email: ginsberg@cisco.com 564 Peter Psenak 565 Cisco Systems 566 Apollo Business Center Mlynske nivy 43 567 Bratislava 821 09 568 Slovakia 570 Email: ppsenak@cisco.com 572 Stefano Previdi 573 Cisco Systems 574 Via Del Serafico 200 575 Rome 0144 576 Italy 578 Email: sprevidi@cisco.com 579 Wim Henderickx 580 Nokia 581 Copernicuslaan 50 582 Antwerp 2018 94089 583 Belgium 585 Email: wim.henderickx@nokia.com