Networking Working Group L. Ginsberg Internet-Draft P. Psenak Intended status: Standards Track Cisco Systems Expires: April 20, 2019 S. Previdi Huawei W. Henderickx Nokia J. Drake Juniper Networks October 17, 2018 IS-IS TE Attributes per application draft-ietf-isis-te-app-05.txt Abstract Existing traffic engineering related link attribute advertisements have been defined and are used in RSVP-TE deployments. In cases where multiple applications wish to make use of these link attributes the current advertisements do not support application specific values for a given attribute nor do they support indication of which applications are using the advertised value for a given link. This draft introduces new link attribute advertisements which address both of these shortcomings. It also discusses backwards compatibility issues and how to minimize duplicate advertisements in the presence of routers which do not support the extensions defined in this document. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Ginsberg, et al. Expires April 20, 2019 [Page 1] Internet-Draft draft-ietf-isis-te-app October 2018 Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on April 20, 2019. Copyright Notice Copyright (c) 2018 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Requirements Discussion . . . . . . . . . . . . . . . . . . . 3 3. Legacy Advertisements . . . . . . . . . . . . . . . . . . . . 4 3.1. Legacy sub-TLVs . . . . . . . . . . . . . . . . . . . . . 4 3.2. Legacy SRLG Advertisements . . . . . . . . . . . . . . . 5 4. Advertising Application Specific Link Attributes . . . . . . 5 4.1. Application Identifier Bit Mask . . . . . . . . . . . . . 6 4.2. Application Specific Link Attributes sub-TLV . . . . . . 8 4.2.1. Special Considerations for Maximum Link Bandwidth . . 9 4.2.2. Special Considerations for Unreserved Bandwidth . . . 9 4.3. Application Specific SRLG TLV . . . . . . . . . . . . . . 9 5. Deployment Considerations . . . . . . . . . . . . . . . . . . 10 6. Attribute Advertisements and Enablement . . . . . . . . . . . 11 7. Interoperability, Backwards Compatibility and Migration Concerns . . . . . . . . . . . . . . . . . . . . . . . . . . 12 7.1. RSVP-TE only deployments . . . . . . . . . . . . . . . . 12 7.2. Multiple Applications: Common Attributes with RSVP-TE . 12 7.3. Multiple Applications: All Attributes Not Shared w RSVP- TE . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 7.4. Deprecating legacy advertisements . . . . . . . . . . . . 13 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 9. Security Considerations . . . . . . . . . . . . . . . . . . . 15 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 15 Ginsberg, et al. Expires April 20, 2019 [Page 2] Internet-Draft draft-ietf-isis-te-app October 2018 11.1. Normative References . . . . . . . . . . . . . . . . . . 15 11.2. Informative References . . . . . . . . . . . . . . . . . 16 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17 1. Introduction Advertisement of link attributes by the Intermediate-System-to- Intermediate-System (IS-IS) protocol in support of traffic engineering (TE) was introduced by [RFC5305] and extended by [RFC5307], [RFC6119], and [RFC7810]. Use of these extensions has been associated with deployments supporting Traffic Engineering over Multiprotocol Label Switching (MPLS) in the presence of Resource Reservation Protocol (RSVP) - more succinctly referred to as RSVP-TE. In recent years new applications have been introduced which have use cases for many of the link attributes historically used by RSVP-TE. Such applications include Segment Routing Traffic Engineering (SRTE) and Loop Free Alternates (LFA). This has introduced ambiguity in that if a deployment includes a mix of RSVP-TE support and SRTE support (for example) it is not possible to unambiguously indicate which advertisements are to be used by RSVP-TE and which advertisements are to be used by SRTE. If the topologies are fully congruent this may not be an issue, but any incongruence leads to ambiguity. An additional issue arises in cases where both applications are supported on a link but the link attribute values associated with each application differ. Current advertisements do not support advertising application specific values for the same attribute on a specific link. This document defines extensions which address these issues. Also, as evolution of use cases for link attributes can be expected to continue in the years to come, this document defines a solution which is easily extensible to the introduction of new applications and new use cases. 2. Requirements Discussion As stated previously, evolution of use cases for link attributes can be expected to continue - so any discussion of existing use cases is limited to requirements which are known at the time of this writing. However, in order to determine the functionality required beyond what already exists in IS-IS, it is only necessary to discuss use cases which justify the key points identified in the introduction - which are: Ginsberg, et al. Expires April 20, 2019 [Page 3] Internet-Draft draft-ietf-isis-te-app October 2018 1. Support for indicating which applications are using the link attribute advertisements on a link 2. Support for advertising application specific values for the same attribute on a link [RFC7855] discusses use cases/requirements for SR. Included among these use cases is SRTE which is defined in [I-D.filsfils-spring-segment-routing-policy]. If both RSVP-TE and SRTE are deployed in a network, link attribute advertisements can be used by one or both of these applications. As there is no requirement for the link attributes advertised on a given link used by SRTE to be identical to the link attributes advertised on that same link used by RSVP-TE, there is a clear requirement to indicate independently which link attribute advertisements are to be used by each application. As the number of applications which may wish to utilize link attributes may grow in the future, an additional requirement is that the extensions defined allow the association of additional applications to link attributes without altering the format of the advertisements or introducing new backwards compatibility issues. Finally, there may still be many cases where a single attribute value can be shared among multiple applications, so the solution must minimize advertising duplicate link/attribute pairs whenever possible. 3. Legacy Advertisements There are existing advertisements used in support of RSVP-TE. These advertisements include sub-TLVs for TLVs 22, 23, 141, 222, and 223 and TLVs for SRLG advertisement. 3.1. Legacy sub-TLVs Ginsberg, et al. Expires April 20, 2019 [Page 4] Internet-Draft draft-ietf-isis-te-app October 2018 Sub-TLVs for TLVs 22, 23, 141, 222, and 223 Code Point/Attribute Name -------------------------- 3 Administrative group (color) 9 Maximum link bandwidth 10 Maximum reservable link bandwidth 11 Unreserved bandwidth 14 Extended Administrative Group 18 TE Default Metric 33 Unidirectional Link Delay 34 Min/Max Unidirectional Link Delay 35 Unidirectional Delay Variation 36 Unidirectional Link Loss 37 Unidirectional Residual Bandwidth 38 Unidirectional Available Bandwidth 39 Unidirectional Utilized Bandwidth 3.2. Legacy SRLG Advertisements TLV 138 GMPLS-SRLG Supports links identified by IPv4 addresses and unnumbered links TLV 139 IPv6 SRLG Supports links identified by IPv6 addresses Note that [RFC6119] prohibits the use of TLV 139 when it is possible to use TLV 138. 4. Advertising Application Specific Link Attributes Two new code points are defined in support of Application Specific Link Attribute Advertisements: 1) Application Specific Link Attributes sub-TLV for TLVs 22, 23, 141, 222, and 223 2)Application Specific Shared Risk Link Group (SRLG) TLV In support of these new advertisements, an application bit mask is defined which identifies the application(s) associated with a given advertisement. The following sections define the format of these new advertisements. Ginsberg, et al. Expires April 20, 2019 [Page 5] Internet-Draft draft-ietf-isis-te-app October 2018 4.1. Application Identifier Bit Mask Identification of the set of applications associated with link attribute advertisements utilizes two bit masks. One bit mask is for standard applications where the definition of each bit is defined in a new IANA controlled registry. A second bit mask is for non- standard User Defined Applications(UDAs). The encoding defined below is used by both the Application Specific Link Attributes sub-TLV and the Application Specific SRLG TLV. 0 1 2 3 4 5 6 7 +-+-+-+-+-+-+-+-+ | SABML+F | 1 octet +-+-+-+-+-+-+-+-+ | UDABML+F | 1 octet +-+-+-+-+-+-+-+-+ | SABM ... 0 - 127 octets +-+-+-+-+-+-+-+-+ | UDABM ... 0 - 127 octets +-+-+-+-+-+-+-+-+ SABML+F (1 octet) Standard Application Bit Mask Length/Flags 0 1 2 3 4 5 6 7 +-+-+-+-+-+-+-+-+ |L| SA-Length | +-+-+-+-+-+-+-+-+ L-flag: Applications listed (both Standard and User Defined) MUST use the legacy advertisements for the corresponding link found in TLVs 22, 23, 141, 222, and 223 or TLV 138 or TLV 139 as appropriate. SA-Length: Indicates the length in octets (0-127) of the Bit Mask for Standard Applications. UDABML+F (1 octet) User Defined Application Bit Mask Length/Flags 0 1 2 3 4 5 6 7 +-+-+-+-+-+-+-+-+ |R| UDA-Length | +-+-+-+-+-+-+-+-+ R: Reserved. Transmitted as 0 and ignored on receipt Ginsberg, et al. Expires April 20, 2019 [Page 6] Internet-Draft draft-ietf-isis-te-app October 2018 UDA-Length: Indicates the length in octets (0-127) of the Bit Mask for User Defined Applications. SABM (variable length) Standard Application Bit Mask (SA-Length * 8) bits This is omitted if SA-Length is 0. 0 1 2 3 4 5 6 7 ... +-+-+-+-+-+-+-+-+... |R|S|F|X| ... +-+-+-+-+-+-+-+-+... R-bit: RSVP-TE S-bit: Segment Routing Traffic Engineering F-bit: Loop Free Alternate X-bit: Flex-Algo UDABM (variable length) User Defined Application Bit Mask (UDA Length * 8) bits 0 1 2 3 4 5 6 7 ... +-+-+-+-+-+-+-+-+... | ... +-+-+-+-+-+-+-+-+... This is omitted if UDA-Length is 0. NOTE: If both SA-length and UDA-Length are zero, then the attributes associated with this attribute identifier bit mask MAY be used by any Standard Application and any User Defined Application. Standard Application Bits are defined/sent starting with Bit 0. Additional bit definitions that may be defined in the future SHOULD be assigned in ascending bit order so as to minimize the number of octets that will need to be transmitted. Undefined bits MUST be Ginsberg, et al. Expires April 20, 2019 [Page 7] Internet-Draft draft-ietf-isis-te-app October 2018 transmitted as 0 and MUST be ignored on receipt. Bits that are NOT transmitted MUST be treated as if they are set to 0 on receipt. User Defined Application bits have no relationship to Standard Application bits and are NOT managed by IANA or any other standards body. It is recommended that bits are used starting with Bit 0 so as to minimize the number of octets required to advertise all UDAs. 4.2. Application Specific Link Attributes sub-TLV A new sub-TLV for TLVs 22, 23, 141, 222, and 223 is defined which supports specification of the applications and application specific attribute values. Type: 16 (suggested value - to be assigned by IANA) Length: Variable (1 octet) Value: Application Bit Mask (as defined in Section 3.1) Link Attribute sub-sub-TLVs - format matches the existing formats defined in [RFC5305] and [RFC7810] When the L-flag is set in the Application Identifiers, all of the applications specified in the bit mask MUST use the link attribute sub-TLV advertisements listed in Section 3.1 for the corresponding link. Application specific link attribute sub-sub-TLVs for the corresponding link attributes MUST NOT be advertised for the set of applications specified in the Standard/User Application Bit Masks and all such advertisements MUST be ignored on receipt. Multiple sub-TLVs for the same link MAY be advertised. When multiple sub-TLVs for the same link are advertised, they SHOULD advertise non- conflicting application/attribute pairs. A conflict exists when the same application is associated with two different values of the same link attribute for a given link. In cases where conflicting values for the same application/attribute/link are advertised all the conflicting values MUST be ignored. For a given application, the setting of the L-flag MUST be the same in all sub-TLVs for a given link. In cases where this constraint is violated, the L-flag MUST be considered set for this application. A new registry of sub-sub-TLVs is to be created by IANA which defines the link attribute sub-sub-TLV code points. A sub-sub-TLV is defined for each of the existing sub-TLVs listed in Section 3.1 except as noted below. The format of the sub-sub-TLVs matches the format of Ginsberg, et al. Expires April 20, 2019 [Page 8] Internet-Draft draft-ietf-isis-te-app October 2018 the corresponding legacy sub-TLV and IANA is requested to assign the legacy sub-TLV identifer to the corresponding sub-sub-TLV. 4.2.1. Special Considerations for Maximum Link Bandwidth Maximum link bandwidth is an application independent attribute of the link. When advertised using the Application Specific Link Attributes sub-TLV, multiple values for the same link MUST NOT be advertised. This can be accomplished most efficiently by having a single advertisement for a given link where the Application Bit Mask identifies all the applications which are making use of the value for that link. It is also possible to advertise the same value for a given link multiple times with disjoint sets of applications specified in the Application Bit Mask. This is less efficient but still valid. If different values for Maximum Link Bandwidth for a given link are advertised, all values MUST be ignored. 4.2.2. Special Considerations for Unreserved Bandwidth Unreserved bandwidth is an attribute specific to RSVP. When advertised using the Application Specific Link Attributes sub-TLV, bits other than the RSVP-TE(R-bit) MUST NOT be set in the Application Bit Mask. If an advertisement of Unreserved Bandwidth is received with bits other than the RSVP-TE bit set, the advertisement MUST be ignored. 4.3. Application Specific SRLG TLV A new TLV is defined to advertise application specific SRLGs for a given link. Although similar in functionality to TLV 138 (defined by [RFC5307]) and TLV 139 (defined by [RFC6119], a single TLV provides support for IPv4, IPv6, and unnumbered identifiers for a link. Unlike TLVs 138/139, it utilizes sub-TLVs to encode the link identifiers in order to provide the flexible formatting required to support multiple link identifier types. Ginsberg, et al. Expires April 20, 2019 [Page 9] Internet-Draft draft-ietf-isis-te-app October 2018 Type: 238 (Suggested value - to be assigned by IANA) Length: Number of octets in the value field (1 octet) Value: Neighbor System-ID + pseudo-node ID (7 octets) Application Bit Mask (as defined in Section 3.1) Length of sub-TLVs (1 octet) Link Identifier sub-TLVs (variable) 0 or more SRLG Values (Each value is 4 octets) The following Link Identifier sub-TLVs are defined. The type values are suggested and will be assigned by IANA - but as the formats are identical to existing sub-TLVs defined for TLVs 22, 23, 141, 222, and 223 the use of the suggested sub-TLV types is strongly encouraged. Type Description 4 Link Local/Remote Identifiers (see [RFC5307]) 6 IPv4 interface address (see [RFC5305]) 8 IPv4 neighbor address (see [RFC5305]) 12 IPv6 Interface Address (see [RFC6119]) 13 IPv6 Neighbor Address (see [RFC6119]) At least one set of link identifiers (IPv4, IPv6, or unnumbered) MUST be present. TLVs which do not meet this requirement MUST be ignored. Multiple TLVs for the same link MAY be advertised. When the L-flag is set in the Application Identifiers, SRLG values MUST NOT be included in the TLV. Any SRLG values which are advertised MUST be ignored. Based on the link identifiers advertised the corresponding legacy TLV (see Section 3.2) can be identified and the SRLG values advertised in the legacy TLV MUST be used by the set of applications specified in the Application Bit Mask. For a given application, the setting of the L-flag MUST be the same in all TLVs for a given link. In cases where this constraint is violated, the L-flag MUST be considered set for this application. 5. Deployment Considerations If link attributes are advertised associated with zero length application bit masks for both standard applications and user defined applications, then that set of link attributes MAY be used by any application. If support for a new application is introduced on any node in a network in the presence of such advertisements, these advertisements MAY be used by the new application. If this is not what is intended, then existing advertisements MUST be readvertised Ginsberg, et al. Expires April 20, 2019 [Page 10] Internet-Draft draft-ietf-isis-te-app October 2018 with an explicit set of applications specified before a new application is introduced. 6. Attribute Advertisements and Enablement This document defines extensions to support the advertisement of application specific link attributes. Whether the presence of link attribute advertisements for a given application indicates that the application is enabled on that link depends upon the application. Similarly, whether the absence of link attribute advertisements indicates that the application is not enabled depends upon the application. In the case of RSVP-TE, the advertisement of application specific link attributes implies that RSVP is enabled on that link. In the case of SRTE, advertisement of application specific link attributes does NOT indicate enablement of SRTE. The advertisements are only used to support constraints which may be applied when specifying an explicit path. SRTE is implicitly enabled on all links which are part of the Segment Routing enabled topology independent of the existence of link attribute advertisements In the case of LFA, advertisement of application specific link attributes does NOT indicate enablement of LFA on that link. Enablement is controlled by local configuration. In the case of Flex-Algo, advertisement of application specific link attributes does NOT indicate enablement of Flex-Algo. Rather the attributes are used to determine what links are included/excluded in the algorithm specific constrained SPF. This is fully specified in [I-D.hegdeppsenak-isis-sr-flex-algo]. If, in the future, additional standard applications are defined to use this mechanism, the specification defining this use MUST define the relationship between application specific link attribute advertisements and enablement for that application. This document allows the advertisement of application specific link attributes with no application identifiers i.e., both the Standard Application Bit Mask and the User Defined Application Bit Mask are not present (See Section 4.1). This supports the use of the link attribute by any application. In the presence of an application where the advertisement of link attribute advertisements is used to infer the enablement of an application on that link (e.g., RSVP-TE), the absence of the application identifier leaves ambiguous whether Ginsberg, et al. Expires April 20, 2019 [Page 11] Internet-Draft draft-ietf-isis-te-app October 2018 that application is enabled on such a link. This needs to be considered when making use of the "any application" encoding. 7. Interoperability, Backwards Compatibility and Migration Concerns Existing deployments of RSVP-TE utilize the legacy advertisements listed in Section 3. Routers which do not support the extensions defined in this document will only process legacy advertisements and are likely to infer that RSVP-TE is enabled on the links for which legacy advertisements exist. It is expected that deployments using the legacy advertisements will persist for a significant period of time - therefore deployments using the extensions defined in this document must be able to co-exist with use of the legacy advertisements by routers which do not support the extensions defined in this document. The following sub-sections discuss interoperability and backwards compatibility concerns for a number of deployment scenarios. Note that in all cases the defined strategy can be employed on a per link basis. 7.1. RSVP-TE only deployments In deployments where RSVP-TE is the only application utilizing link attribute advertisements, use of the the legacy advertisements can continue without change. 7.2. Multiple Applications: Common Attributes with RSVP-TE In cases where multiple applications are utilizing a given link, one of the applications is RSVP-TE, and all link attributes for a given link are common to the set of applications utilizing that link, interoperability is achieved by using legacy advertisements and sending application specific advertisements with L-bit set and no link attribute values. This avoids duplication of link attribute advertisements. 7.3. Multiple Applications: All Attributes Not Shared w RSVP-TE In cases where one or more applications other than RSVP-TE are utilizing a given link and one or more link attribute values are NOT shared with RSVP-TE, it is necessary to use application specific advertisements as defined in this document. Attributes for applications other than RSVP-TE MUST be advertised using application specific advertisements which have the L-bit clear. In cases where some link attributes are shared with RSVP-TE, this requires duplicate advertisements for those attributes. Ginsberg, et al. Expires April 20, 2019 [Page 12] Internet-Draft draft-ietf-isis-te-app October 2018 The discussion in this section applies to cases where RSVP-TE is NOT using any advertised attributes on a link and to cases where RSVP-TE is using some link attribute advertisements on the link but some link attributes cannot be shared with RSVP-TE. 7.4. Deprecating legacy advertisements The extensions defined in this document support RSVP-TE as one of the supported applications - so a long term goal for deployments would be to deprecate use of the legacy advertisements in support of RSVP-TE. This can be done in the following step-wise manner: 1)Upgrade all routers to support extensions in this document 2)Readvertise all legacy link attributes using application specific advertisements with L-bit clear and R-bit set. 3)Remove legacy advertisements 8. IANA Considerations This document defines a new sub-TLV for TLVs 22, 23, 141, 222, and 223. Type Description 22 23 25 141 222 223 ---- --------------------- ---- ---- ---- ---- ---- ---- 16 Application Specific y y y(s) y y y Link Attributes This document defines one new TLV: Type Description IIH LSP SNP Purge ---- --------------------- --- --- --- ----- 238 Application Specific n y n n SRLG This document requests a new IANA registry be created to control the assignment of sub-sub-TLV codepoints for the Application Specific Link Attributes sub-TLV. The suggested name of the new registry is "sub-sub-TLV code points for application specific link attributes". The registration procedure is "Expert Review" as defined in [RFC8126]. The following assignments are made by this document: Ginsberg, et al. Expires April 20, 2019 [Page 13] Internet-Draft draft-ietf-isis-te-app October 2018 Type Description --------------------------------------------------------- 0-2 Unassigned 3 Administrative group (color) 4-8 Unassigned 9 Maximum link bandwidth 10 Maximum reservable link bandwidth 11 Unreserved bandwidth 12-13 Unassigned 14 Extended Administrative Group 15-17 Unassigned 18 TE Default Metric 19-32 Unassigned 33 Unidirectional Link Delay 34 Min/Max Unidirectional Link Delay 35 Unidirectional Delay Variation 36 Unidirectional Link Loss 37 Unidirectional Residual Bandwidth 38 Unidirectional Available Bandwidth 39 Unidirectional Utilized Bandwidth 40-255 Unassigned This document requests a new IANA registry be created, under the category of "Interior Gateway Protocol (IGP) Parameters", to control the assignment of application bit identifiers. The suggested name of the new registry is "Link Attribute Applications". The registration policy for this registry is "Standards Action" ([RFC8126] and [RFC7120]). The following assignments are made by this document: Bit # Name --------------------------------------------------------- 0 RSVP-TE (R-bit) 1 Segment Routing Traffic Engineering (S-bit) 2 Loop Free Alternate (F-bit) 3 Flex Algorithm (X-bit) This document requests a new IANA registry be created to control the assignment of sub-TLV types for the application specific SRLG TLV. The suggested name of the new registry is "Sub-TLVs for TLV 238". The registration procedure is "Expert Review" as defined in [RFC8126]. The following assignments are made by this document: Ginsberg, et al. Expires April 20, 2019 [Page 14] Internet-Draft draft-ietf-isis-te-app October 2018 Value Description --------------------------------------------------------- 0-3 Unassigned 4 Link Local/Remote Identifiers (see [RFC5307]) 5 Unassigned 6 IPv4 interface address (see [RFC5305]) 7 Unassigned 8 IPv4 neighbor address (see [RFC5305]) 9-11 Unassigned 12 IPv6 Interface Address (see [RFC6119]) 13 IPv6 Neighbor Address (see [RFC6119]) 14-255 Unassigned 9. Security Considerations Security concerns for IS-IS are addressed in [ISO10589, [RFC5304], and [RFC5310]. 10. Acknowledgements The authors would like to thank Eric Rosen and Acee Lindem for their careful review and content suggestions. 11. References 11.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC5304] Li, T. and R. Atkinson, "IS-IS Cryptographic Authentication", RFC 5304, DOI 10.17487/RFC5304, October 2008, . [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic Engineering", RFC 5305, DOI 10.17487/RFC5305, October 2008, . [RFC5307] Kompella, K., Ed. and Y. Rekhter, Ed., "IS-IS Extensions in Support of Generalized Multi-Protocol Label Switching (GMPLS)", RFC 5307, DOI 10.17487/RFC5307, October 2008, . Ginsberg, et al. Expires April 20, 2019 [Page 15] Internet-Draft draft-ietf-isis-te-app October 2018 [RFC5310] Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R., and M. Fanto, "IS-IS Generic Cryptographic Authentication", RFC 5310, DOI 10.17487/RFC5310, February 2009, . [RFC6119] Harrison, J., Berger, J., and M. Bartlett, "IPv6 Traffic Engineering in IS-IS", RFC 6119, DOI 10.17487/RFC6119, February 2011, . [RFC7120] Cotton, M., "Early IANA Allocation of Standards Track Code Points", BCP 100, RFC 7120, DOI 10.17487/RFC7120, January 2014, . [RFC7810] Previdi, S., Ed., Giacalone, S., Ward, D., Drake, J., and Q. Wu, "IS-IS Traffic Engineering (TE) Metric Extensions", RFC 7810, DOI 10.17487/RFC7810, May 2016, . [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 8126, DOI 10.17487/RFC8126, June 2017, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . 11.2. Informative References [I-D.filsfils-spring-segment-routing-policy] Filsfils, C., Sivabalan, S., Hegde, S., daniel.voyer@bell.ca, d., Lin, S., bogdanov@google.com, b., Krol, P., Horneffer, M., Steinberg, D., Decraene, B., Litkowski, S., Mattes, P., Ali, Z., Talaulikar, K., Liste, J., Clad, F., and K. Raza, "Segment Routing Policy Architecture", draft-filsfils-spring-segment-routing- policy-06 (work in progress), May 2018. [I-D.hegdeppsenak-isis-sr-flex-algo] Psenak, P., Hegde, S., Filsfils, C., and A. Gulko, "ISIS Segment Routing Flexible Algorithm", draft-hegdeppsenak- isis-sr-flex-algo-02 (work in progress), February 2018. [RFC7855] Previdi, S., Ed., Filsfils, C., Ed., Decraene, B., Litkowski, S., Horneffer, M., and R. Shakir, "Source Packet Routing in Networking (SPRING) Problem Statement and Requirements", RFC 7855, DOI 10.17487/RFC7855, May 2016, . Ginsberg, et al. Expires April 20, 2019 [Page 16] Internet-Draft draft-ietf-isis-te-app October 2018 Authors' Addresses Les Ginsberg Cisco Systems 821 Alder Drive Milpitas, CA 95035 USA Email: ginsberg@cisco.com Peter Psenak Cisco Systems Apollo Business Center Mlynske nivy 43 Bratislava 821 09 Slovakia Email: ppsenak@cisco.com Stefano Previdi Huawei Email: stefano@previdi.net Wim Henderickx Nokia Copernicuslaan 50 Antwerp 2018 94089 Belgium Email: wim.henderickx@nokia.com John Drake Juniper Networks Email: jdrake@juniper.net Ginsberg, et al. Expires April 20, 2019 [Page 17]