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Versions: (draft-xu-ospf-mpls-elc) 00 01 02 03 04 05 06 07 08 09 10 11 12

Network Working Group                                              X. Xu
Internet-Draft                                                    Huawei
Intended status: Standards Track                                 S. Kini
Expires: November 4, 2016                                       Ericsson
                                                            S. Sivabalan
                                                             C. Filsfils
                                                                   Cisco
                                                            S. Litkowski
                                                                  Orange
                                                             May 3, 2016


             Signaling Entropy Label Capability Using OSPF
                      draft-ietf-ospf-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 via signaling that it can process ELs on
   that tunnel.  This draft defines a mechanism to signal that
   capability using OSPF.  This mechanism is useful when the label
   advertisement is also done via OSPF.

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
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   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   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 November 4, 2016.

Copyright Notice

   Copyright (c) 2016 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
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   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 OSPF  . . . . . . . . . . . . . . . . .   3
   4.  Advertising RLDC Using OSPF . . . . . . . . . . . . . . . . .   3
   5.  Usage and Applicability . . . . . . . . . . . . . . . . . . .   4
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   4
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   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 on
   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 OSPF
   [I-D.ietf-ospf-segment-routing-extensions] . In such scenario the
   signaling mechanisms defined in [RFC6790] are inadequate.  This draft
   defines a mechanism to signal the ELC using OSPF.  This mechanism is
   useful when the label advertisement is also done via OSPF.  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 Deepth Capability (RLDC) 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,



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   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.

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 [RFC4970].

3.  Advertising ELC Using OSPF

   The OSPF Router Information (RI) Opaque LSA defined in [RFC4970] is
   used by OSPF routers to announce their capabilities.  A new TLV
   within the body of this LSA, called ELC TLV is defined to advertise
   the capability of the router to process the ELs.  As showed in
   Figure 1, it is formatted as described in Section 2.1 of [RFC4970].
   The Type for the ELC TLV needs to be assigned by IANA and it has a
   Length of zero.  The scope of the advertisement depends on the
   application but it is recommended that it SHOULD be AS-scoped.  If a
   router has multiple linecards, the router MUST NOT announce the ELC
   unless all of its linecards are capable of processing ELs.  This TLV
   is applicable to both OSPFv2 and OSPFv3.

      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 TLV Format.

4.  Advertising RLDC Using OSPF

   A new TLV within the body of the OSPF RI LSA, called RLDC TLV is
   defined to advertise the capability of the router to read the maximum
   label stack depth.  As showed in Figure 2, it is formatted as
   described in Section 2.1 of [RFC4970] 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 depth 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




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   deepth, the router MUST advertise the smallest one in the RLDC TLV.
   This TLV is applicable to both OSPFv2 and OSPFv3.

      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             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |     RLD       |
     +-+-+-+-+-+-+-+-+
                        Figure 2: RLDC TLV Format

5.  Usage and Applicability

   The EL capability is used by ingress LSRs to determine whether an EL
   could be inserted into a given LSP tunnel.  The RLD capability 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 EL capability and RLD capability using OSPF.  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.  IANA Considerations

   This memo includes a request to IANA to allocate two TLV types from
   the OSPF RI TLVs registry.

8.  Security Considerations

   The security considerations as described in [RFC4970] is appliable to
   this document.  This document does not introduce any new security
   risk.

9.  References

9.1.  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>.



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   [RFC4970]  Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and
              S. Shaffer, "Extensions to OSPF for Advertising Optional
              Router Capabilities", RFC 4970, DOI 10.17487/RFC4970, July
              2007, <http://www.rfc-editor.org/info/rfc4970>.

9.2.  Informative References

   [I-D.ietf-mpls-spring-entropy-label]
              Kini, S., Kompella, K., Sivabalan, S., Litkowski, S.,
              Shakir, R., and j. jefftant@gmail.com, "Entropy labels for
              source routed tunnels with label stacks", draft-ietf-mpls-
              spring-entropy-label-03 (work in progress), April 2016.

   [I-D.ietf-ospf-segment-routing-extensions]
              Psenak, P., Previdi, S., Filsfils, C., Gredler, H.,
              Shakir, R., Henderickx, W., and J. Tantsura, "OSPF
              Extensions for Segment Routing", draft-ietf-ospf-segment-
              routing-extensions-08 (work in progress), April 2016.

   [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-04 (work in
              progress), March 2016.

   [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>.

Authors' Addresses

   Xiaohu Xu
   Huawei

   Email: xuxiaohu@huawei.com


   Sriganesh Kini
   Ericsson

   Email: sriganesh.kini@ericsson.com








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   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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