ISIS Working Group X. Xu Internet-Draft Huawei Intended status: Standards Track S. Kini Expires:April 17, 2017July 7, 2018 Ericsson S. Sivabalan C. Filsfils Cisco S. Litkowski OrangeOctober 14, 2016January 3, 2018 Signaling Entropy Label Capability and Readable Label-stack Depth Using IS-ISdraft-ietf-isis-mpls-elc-02draft-ietf-isis-mpls-elc-03 AbstractMulti ProtocolMultiprotocol Label Switching (MPLS) has defined a mechanism to load balance traffic flows using Entropy Labels (EL). An ingressLSRLabel Switching Router (LSR) cannot insert ELs for packets going into a given tunnel unless an egress LSR has indicated via signaling that itcan process ELshas the capability of processing ELs, referred to as Entropy Label Capability (ELC), on that tunnel. In addition, it would be useful for ingress LSRs to know each LSR's capability of reading the maximum label stack depth, referred to as Readable Label-stack Depth (RLD), in the cases where stacked LSPs are used for whatever reasons. Thisdraftdocument definesa mechanismmechanisms to signalthat capabilitythese two capabilities usingIS-IS. This mechanism isOSPF. These mechanisms are useful when the label advertisement is also done via IS-IS. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. 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 athttp://datatracker.ietf.org/drafts/current/.https://datatracker.ietf.org/drafts/current/. 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 onApril 17, 2017.July 7, 2018. Copyright Notice Copyright (c)20162018 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(http://trustee.ietf.org/license-info)(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 . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Advertising ELC Using IS-IS . . . . . . . . . . . . . . . . . 3 4. AdvertisingRLDCRLD Using IS-IS . . . . . . . . . . . . . . . . . 3 5.Usage and Applicability . . . . . . . . . . . . . . . . . . . 4 6.Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 47.6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 48.7. Security Considerations . . . . . . . . . . . . . . . . . . . 49.8. References . . . . . . . . . . . . . . . . . . . . . . . . . 49.1.8.1. Normative References . . . . . . . . . . . . . . . . . . 49.2.8.2. Informative References . . . . . . . . . . . . . . . . .54 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 1. IntroductionMulti Protocol Label Switching (MPLS) has defined[RFC6790] describes a methodin [RFC6790]to load balance Multiprotocol Label Switching (MPLS) traffic flows using Entropy Labels (EL).An ingress LSR cannot insert ELs for packets going into a given tunnel unless an egress LSR has indicated that it can process ELs on that tunnel.[RFC6790]definesintroduces thesignalingconcept ofthis capability (a.k.a.,Entropy Label Capability- ELC)(ELC) and defines the signalings of this capability via MPLS signaling protocols. Recently, mechanisms are being defined to signal labels vialinklink- state Interior Gateway Protocols (IGP) such as IS-IS[I-D.ietf-isis-segment-routing-extensions] .[I-D.ietf-isis-segment-routing-extensions]. In suchscenarioscenario, the signaling mechanisms defined in [RFC6790] are inadequate. This draft defines a mechanism to signal the ELC [RFC6790] using IS-IS. This mechanism is useful when the label advertisement is also done viaIS-IS.IS- IS. In addition, in the cases where stacked LSPs are used for whatever reasons (e.g., SPRING-MPLS [I-D.ietf-spring-segment-routing-mpls]), it would be useful for ingress LSRs to know each LSR's capability of reading the maximum label stackdeepth.depth. This capability, referred to as ReadableLabel Deepth Capability (RLDC) canLabel- stack Depth (RLD) may be used by ingress LSRs to determine whether it's necessary to insert an EL for a given LSP of the stacked LSP tunnel in the case where there has already been at least one EL in the label stack[I-D.ietf-mpls-spring-entropy-label] . Of course, even it has been determined that it's neccessary to insert an EL for a given LSP tunnel, if the egress LSR of that LSP tunnel has not yet indicated that it can process ELs for that tunnel, the ingress LSR MUST NOT include an entropy label for that tunnel as well.[I-D.ietf-mpls-spring-entropy-label]. 2. Terminology This memo makes use of the terms defined in [RFC6790] and [RFC4971]. 3. Advertising ELC Using IS-IS The IS-IS Router CAPABILITY TLV as defined in [RFC4971] is used by IS-IS routers to announce their capabilities. A new sub-TLV of this TLV, called ELC sub-TLV is defined to advertise the capability of the router to process the ELs.ItAs shown in Figure 1, it is formatted as described in [RFC5305] with a Type code to be assigned by IANA and a Length of zero. The scope of the advertisement depends on the application but it is RECOMMENDED that it SHOULD be domain-wide. If a router has multiple linecards, the router MUST NOT advertise the ELC unless all of the linecards are capable of processing ELs. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type=TBD1 | Length=0 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: ELC sub-TLV Format 4. AdvertisingRLDCRLD Using IS-IS A new sub-TLV of the IS-IS Router CAPABILITY TLV, calledRLDCRLD sub-TLV is defined to advertise the capability of the router to read the maximum label stack depth. As shown in Figure 2, it is formatted as described in [RFC5305] with a Type code to be assigned by IANA and a Length of one. The Value field is set to the maximum readable label stack deepth in the range between 1 to 255. The scope of the advertisement depends on the application but it is RECOMMENDED that it SHOULD be domain-wide. If a router has multiple linecards with different capabilities of reading the maximum label stack deepth, the router MUST advertise the smallest one in the RLDC sub-TLV. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type=TBD2 | Length=1 | RLD | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2:RLDCRLD sub-TLV Format 5.Usage and Applicability The ELC is used by ingress LSRs to determine whether an EL could be inserted into a given LSP tunnel. The RLDC is used by ingress LSRs to determine whether it's necessary to insert an EL for a given LSP tunnel in the case where there has already been at least one EL in the label stack. This document only describes how to signal the ELC and RLDC using IS-IS. As for how to apply those capabilities when inserting EL(s) into LSP tunnel(s), it's outside the scope of this document and accordingly would be described in [I-D.ietf-mpls-spring-entropy-label]. 6.Acknowledgements The authors would like to thank Yimin Shen, George Swallow, Acee Lindem and Carlos Pignataro for their valuable comments.7.6. IANA Considerations This memo includes a request to IANA to allocate two sub-TLV types within the IS-IS Router Capability TLV.8.7. Security Considerations The security considerations as described in [RFC4971] isappliableapplicable to this document. This document does not introduce any new security risk.9.8. References9.1.8.1. 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,<http://www.rfc-editor.org/info/rfc2119>.<https://www.rfc-editor.org/info/rfc2119>. [RFC4971] Vasseur, JP., Ed., Shen, N., Ed., and R. Aggarwal, Ed., "Intermediate System to Intermediate System (IS-IS) Extensions for Advertising Router Information", RFC 4971, DOI 10.17487/RFC4971, July 2007,<http://www.rfc-editor.org/info/rfc4971>. 9.2.<https://www.rfc-editor.org/info/rfc4971>. 8.2. Informative References [I-D.ietf-isis-segment-routing-extensions] Previdi, S., Ginsberg, L., Filsfils, C., Bashandy, A., Gredler, H., Litkowski, S., Decraene, B., andj. jefftant@gmail.com,J. Tantsura, "IS-IS Extensions for Segment Routing", draft-ietf-isis-segment-routing-extensions-08segment-routing-extensions-15 (work in progress),October 2016.December 2017. [I-D.ietf-mpls-spring-entropy-label] Kini, S., Kompella, K., Sivabalan, S., Litkowski, S., Shakir, R., andj. jefftant@gmail.com,J. Tantsura, "Entropylabels for source routed tunnels withlabelstacks", draft-ietf-mpls- spring-entropy-label-04for SPRING tunnels", draft-ietf-mpls-spring-entropy-label-07 (work in progress),July 2016.October 2017. [I-D.ietf-spring-segment-routing-mpls] Filsfils, C., Previdi, S., Bashandy, A., Decraene, B., Litkowski, S.,Horneffer, M., Shakir, R., jefftant@gmail.com, j.,andE. Crabbe,R. Shakir, "Segment Routing with MPLS data plane",draft-ietf-spring-segment-routing- mpls-05draft-ietf-spring-segment-routing-mpls-11 (work in progress),July 2016.October 2017. [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic Engineering", RFC 5305, DOI 10.17487/RFC5305, October 2008,<http://www.rfc-editor.org/info/rfc5305>.<https://www.rfc-editor.org/info/rfc5305>. [RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and L. Yong, "The Use of Entropy Labels in MPLS Forwarding", RFC 6790, DOI 10.17487/RFC6790, November 2012,<http://www.rfc-editor.org/info/rfc6790>.<https://www.rfc-editor.org/info/rfc6790>. Authors' Addresses Xiaohu Xu Huawei Email:xuxiaohu@huawei.comxuxh.mail@gmail.com Sriganesh Kini Ericsson Email: sriganesh.kini@ericsson.com Siva Sivabalan Cisco Email: msiva@cisco.com Clarence Filsfils Cisco Email: cfilsfil@cisco.com Stephane Litkowski Orange Email: stephane.litkowski@orange.com