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

OSPF Working Group                                                 X. Xu
Internet-Draft                                               Alibaba Inc
Intended status: Standards Track                                 S. Kini
Expires: February 2, 2019
                                                            S. Sivabalan
                                                             C. Filsfils
                                                                   Cisco
                                                            S. Litkowski
                                                                  Orange
                                                         August 01, 2018


  Signaling Entropy Label Capability and Entropy Readable Label-stack
                            Depth Using OSPF
                      draft-ietf-ospf-mpls-elc-06

Abstract

   Multiprotocol Label Switching (MPLS) has defined a mechanism to load
   balance traffic flows using Entropy Labels (EL).  An ingress Label
   Switching Router (LSR) cannot insert ELs for packets going into a
   given tunnel unless an egress LSR has indicated via signaling that it
   has 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 and performing EL-based load-balancing, referred to
   as Entropy Readable Label Depth (ERLD), in the cases where stacked
   LSPs are used for whatever reasons.  This document defines mechanisms
   to signal these two capabilities using OSPF.  These mechanisms are
   useful when the label advertisement is also done via OSPF.  In
   addition, this document introduces the Non-IGP Functional
   Capabilities TLV for advertising OSPF router's actual non-IGP
   functional capabilities.  ELC is one of such non-IGP functional
   capabilities.

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



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   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at 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 on February 2, 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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Non-OSPF Functional Capabilities TLV  . . . . . . . . . . . .   3
   4.  Advertising ELC Using OSPF  . . . . . . . . . . . . . . . . .   4
   5.  Advertising ERLD Using OSPF . . . . . . . . . . . . . . . . .   4
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   4
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   [RFC6790] describes a method to load balance Multiprotocol Label
   Switching (MPLS) traffic flows using Entropy Labels (EL).  [RFC6790]
   introduces the concept of Entropy Label Capability (ELC) and defines
   the signalings of this capability via MPLS signaling protocols.
   Recently, mechanisms are being defined to signal labels via link-
   state Interior Gateway Protocols (IGP) such as OSPF



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   [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 [RFC6790] 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., SR-MPLS [I-D.ietf-spring-segment-routing-mpls]), it
   would be useful for ingress LSRs to know each intermediate LSR's
   capability of reading the maximum label stack depth and performing
   EL-based load-balancing.  This capability, referred to as Entropy
   Readable Label Depth (ERLD) as defined in
   [I-D.ietf-mpls-spring-entropy-label] 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].

2.  Terminology

   This memo makes use of the terms defined in [RFC6790] and [RFC7770].

3.  Non-OSPF Functional Capabilities TLV

   This document defines the Router Non-IGP Functional Capabilities TLV
   with TLV type code of TBD1 within the body of the OSPF Router
   Information LSA.  An OSPF router advertising an OSPF RI LSA MAY
   include the Router Non-IGP Functional Capabilities TLV.  If included,
   it MUST be included in the first instance of the LSA.  Additionally,
   the TLV MUST reflect the advertising OSPF router's actual non-IGP
   functional capabilities in the flooding scope of the containing OSPF
   RI LSA.

   The format of the Router Non-OSPF Functional Capabilities TLV is as
   follows:

        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             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                 Non-IGP Functional Capabilities               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
             Figure 1: Non-OSPF Functional Capabilities TLV Format

      Type: TBD1.

      Length: Indicates the length of the value portion in octets and
      will be a multiple of 4 octets dependent on the number of



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      capabilities advertised.  Initially, the length will be 4,
      denoting 4 octets of Non-IGP Functional Capabilities Bits as
      defined in [I-D.ietf-isis-mpls-elc].

      Value: contains the Non-IGP Functional Capabilities Bits as
      defined in [I-D.ietf-isis-mpls-elc].

   The Non-IGP Functional Capabilities TLV MAY be followed by optional
   TLVs that further specify a non-OSPF functional capability.  In
   contrast to the OSPF Router Functional Capabilities TLV, the non-OSPF
   functional capabilities advertised in this TLV have no impact on the
   OSPF protocol operation.  The specifications for non-IGP functional
   capabilities advertised in this TLV MUST describe protocol behavior
   and address backwards compatibility.

4.  Advertising ELC Using OSPF

   One bit of the Non-IGP Functional Capability Bits for is used to
   indicate the ELC.

   Assignment of a Non-IGP Functional Capability Bit for the ELC is
   defined in [I-D.ietf-isis-mpls-elc].

   If a router has multiple line cards, the router MUST NOT announce the
   ELC [RFC6790] unless all of its linecards are capable of processing
   ELs.

5.  Advertising ERLD Using OSPF

   A new MSD-type of the Node MSD sub-TLV
   [I-D.ietf-isis-segment-routing-msd], called ERLD is defined to
   advertise the ERLD of a given router.  The scope of the advertisement
   depends on the application.

   Assignment of a MSD-Type for ERLD is defined in
   [I-D.ietf-isis-mpls-elc].

   If a router has multiple linecards with different capabilities of
   reading the maximum label stack deepth, the router MUST advertise the
   smallest one.

6.  Acknowledgements

   The authors would like to thank Yimin Shen, George Swallow, Acee
   Lindem, Les Ginsberg, Ketan Talaulikar, Jeff Tantsura and Carlos
   Pignataro for their valuable comments.





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7.  IANA Considerations

   This document requests IANA to allocate one TLV type from the OSPF RI
   TLVs registry for the Non-IGP Functional CapabilitiesTLV.

8.  Security Considerations

   The security considerations as described in [RFC7770] is applicable
   to this document.  This document does not introduce any new security
   risk.

9.  References

9.1.  Normative References

   [I-D.ietf-isis-mpls-elc]
              Xu, X., Kini, S., Sivabalan, S., Filsfils, C., and S.
              Litkowski, "Signaling Entropy Label Capability and Entropy
              Readable Label Depth Using IS-IS", draft-ietf-isis-mpls-
              elc-05 (work in progress), July 2018.

   [I-D.ietf-isis-segment-routing-msd]
              Tantsura, J., Chunduri, U., Aldrin, S., and L. Ginsberg,
              "Signaling MSD (Maximum SID Depth) using IS-IS", draft-
              ietf-isis-segment-routing-msd-13 (work in progress), July
              2018.

   [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-25 (work in progress), April 2018.

   [I-D.ietf-spring-segment-routing-mpls]
              Bashandy, A., Filsfils, C., Previdi, S., Decraene, B.,
              Litkowski, S., and R. Shakir, "Segment Routing with MPLS
              data plane", draft-ietf-spring-segment-routing-mpls-14
              (work in progress), June 2018.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC5305]  Li, T. and H. Smit, "IS-IS Extensions for Traffic
              Engineering", RFC 5305, DOI 10.17487/RFC5305, October
              2008, <https://www.rfc-editor.org/info/rfc5305>.




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   [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,
              <https://www.rfc-editor.org/info/rfc6790>.

   [RFC7770]  Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and
              S. Shaffer, "Extensions to OSPF for Advertising Optional
              Router Capabilities", RFC 7770, DOI 10.17487/RFC7770,
              February 2016, <https://www.rfc-editor.org/info/rfc7770>.

9.2.  Informative References

   [I-D.ietf-mpls-spring-entropy-label]
              Kini, S., Kompella, K., Sivabalan, S., Litkowski, S.,
              Shakir, R., and J. Tantsura, "Entropy label for SPRING
              tunnels", draft-ietf-mpls-spring-entropy-label-12 (work in
              progress), July 2018.

Authors' Addresses

   Xiaohu Xu
   Alibaba Inc

   Email: xiaohu.xxh@alibaba-inc.com


   Sriganesh Kini

   Email: sriganeshkini@gmail.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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