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Versions: 00 01 02 draft-ietf-isis-mpls-elc

Network Working Group                                              X. Xu
Internet-Draft                                                    Huawei
Intended status: Standards Track                                 S. Kini
Expires: October 22, 2015                                       Ericsson
                                                            S. Sivabalan
                                                             C. Filsfils
                                                                   Cisco
                                                            S. Litkowski
                                                                  Orange
                                                          April 20, 2015


             Signaling Entropy Label Capability Using IS-IS
                       draft-xu-isis-mpls-elc-02

Abstract

   Multi Protocol Label Switching (MPLS) has defined a mechanism to load
   balance 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 for that tunnel.
   This draft defines a mechanism to signal that capability using IS-IS.
   This mechanism is useful when the label advertisement is also done
   via IS-IS.

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 http://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 on October 22, 2015.

Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.





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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://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
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Advertising ELC using IS-IS . . . . . . . . . . . . . . . . .   3
   4.  Advertising RLSDC using IS-IS . . . . . . . . . . . . . . . .   3
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   3
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   4
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   Multi Protocol Label Switching (MPLS) has defined a method in
   [RFC6790] to load balance 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 for
   that tunnel.  [RFC6790] defines the signaling of this capability
   (a.k.a Entropy Label Capability - ELC) via signaling protocols.
   Recently, mechanisms are being defined to signal labels via link
   state Interior Gateway Protocols (IGP) such as IS-IS
   [I-D.ietf-isis-segment-routing-extensions].  In such scenario the
   signaling mechanisms defined in [RFC6790] are inadequate.  This draft
   defines a mechanism to signal the ELC using IS-IS.  This mechanism is
   useful when the label advertisement is also done via 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 stack deepth.  This capability, referred to
   as Readable Label Stack Deepth Capability (RLSDC) can be 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 [I-D.ietf-mpls-spring-entropy-label] . Of
   course, even it has been determined that it's neccessary to insert an



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   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.

1.1.  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].

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 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.  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.

4.  Advertising RLSDC using IS-IS

   A new sub-TLV of the IS-IS Router CAPABILITY TLV, called RLSDC sub-
   TLV is defined to advertise the capability of the router to read the
   maximum label stack depth.  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 RLSDC sub-TLV.

5.  Acknowledgements

   The authors would like to thank Yimin Shen and George Swallow for
   their valuable comments on the draft.







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6.  IANA Considerations

   This memo includes a request to IANA to allocate two sub-TLV types
   within the IS-IS Router Capability TLV.

7.  Security Considerations

   This document does not introduce any new security risk.

8.  References

8.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC4971]  Vasseur, JP., Shen, N., and R. Aggarwal, "Intermediate
              System to Intermediate System (IS-IS) Extensions for
              Advertising Router Information", RFC 4971, July 2007.

   [RFC5305]  Li, T. and H. Smit, "IS-IS Extensions for Traffic
              Engineering", RFC 5305, October 2008.

8.2.  Informative References

   [I-D.ietf-isis-segment-routing-extensions]
              Previdi, S., Filsfils, C., Bashandy, A., Gredler, H.,
              Litkowski, S., Decraene, B., and J. Tantsura, "IS-IS
              Extensions for Segment Routing", draft-ietf-isis-segment-
              routing-extensions-03 (work in progress), October 2014.

   [I-D.ietf-mpls-spring-entropy-label]
              Kini, S., Kompella, K., Sivabalan, S., Litkowski, S.,
              Shakir, R., Xu, X., Henderickx, W., and J. Tantsura,
              "Entropy labels for source routed stacked tunnels", draft-
              ietf-mpls-spring-entropy-label-00 (work in progress),
              March 2015.

   [I-D.ietf-spring-segment-routing-mpls]
              Filsfils, C., Previdi, S., Bashandy, A., Decraene, B.,
              Litkowski, S., Horneffer, M., Shakir, R., Tantsura, J.,
              and E. Crabbe, "Segment Routing with MPLS data plane",
              draft-ietf-spring-segment-routing-mpls-00 (work in
              progress), December 2014.

   [RFC6790]  Kompella, K., Drake, J., Amante, S., Henderickx, W., and
              L. Yong, "The Use of Entropy Labels in MPLS Forwarding",
              RFC 6790, November 2012.



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Authors' Addresses

   Xiaohu Xu
   Huawei

   Email: xuxiaohu@huawei.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





















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