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MPLS Working Group                                             R. Raszuk
Internet-Draft                                                    NTT I3
Intended status: Standards Track                         January 2, 2014
Expires: July 6, 2014


                        MPLS Domain Wide Labels
                draft-raszuk-mpls-domain-wide-labels-01

Abstract

   This document describes a mechanism of using concept of Domain Wide
   MPLS Labels in parallel with any of the existing deployments using
   other label distribution and allocation methods where multi protocol
   label switching paradigm is used for transport.  Specifically it
   defines a new type of context label which can be used to
   differentiate lookup tables when using Domain Wide transport Labels
   from other downstream or upstream assigned transport labels.  The end
   result is creation of clean new label space in data plane allowing
   very easy and smooth migration to the number of applications choosing
   to use Domain Wide MPLS Labels.

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 July 6, 2014.

Copyright Notice

   Copyright (c) 2014 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) in effect on the date of
   publication of this document.  Please review these documents



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   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.  MPLS Domain Wide Label Indicator  . . . . . . . . . . . . . .   3
   3.  Control plane . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Data plane  . . . . . . . . . . . . . . . . . . . . . . . . .   3
   5.  Advantages  . . . . . . . . . . . . . . . . . . . . . . . . .   4
   6.  Deployment considerations . . . . . . . . . . . . . . . . . .   4
   7.  Security considerations . . . . . . . . . . . . . . . . . . .   4
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   9.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   4
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     10.1.  Normative References . . . . . . . . . . . . . . . . . .   4
     10.2.  Informative References . . . . . . . . . . . . . . . . .   5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   With the growing number of applications for Domain Wide Labels (by
   some also referred to as "global labels") there is also growing
   concern related to the ease of deployment considering various
   restrictions for available in the platform's data plane label space
   or taking into account existing deployments of LDP, RSVP-TE, BGP3107
   etc and their coexistence with the introduction of new MPLS
   signalling and mpls switching data plane paradigm.

   To list just a few examples number of related work has been already
   seen in this space: Segment Routing
   [I-D.filsfils-rtgwg-segment-routing], PCE
   [I-D.sivabalan-pce-segment-routing], RFC5331 [RFC5331], Advertising
   MPLS labels in IGP [I-D.gredler-rtgwg-igp-label-advertisement], 2547
   egress PE Fast Failure Protection
   [I-D.minto-2547-egress-node-fast-protection] etc...

   Fundamentally there are two solutions to address this problem.  One
   solution revolves around using the notion of local per node label
   pools with offset added at each node resulting in making the label
   locally assigned yet still globally significant.  While doable and
   successfully used as application labels (example: RFC4761 [RFC4761])
   authors believe that for transport the further simplification to such
   scheme is helpful.




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   The second solution described in this memo proposes an explicit
   separation of domain wide label space from any other transport or
   application label space used already today.  Such separation into
   different LFIB is accomplished with the use of new type of context
   label RFC5331 defined as MPLS Domain Wide Label Indicator.

2.  MPLS Domain Wide Label Indicator

   In order to explicitly indicate that next label in the MPLS label
   stack of each transported packet is Domain Wide Labels the new
   context label Domain Wide Label Indicator has been defined.  The
   value of the label is taken from the reserved label pool and has been
   allocated by IANA *TBD*

   The MPLS label stack entry has 4 octets where 20 bits indicate the
   label value, S bit indicates End of Stack, 3 bits indicate QoS value
   and remaining 8 bits indicate TTL field.

   In Domain Wide Label Indicator the label value determines the
   separate LFIB to be used during packet processing.  The S bit MUST be
   set to 0 and QoS bits are to be reserved.  The TTL field MAY be
   copied from the first transport label in the MPLS stack.

3.  Control plane

   The signalling of Domain Wide Labels itself is out of scope of this
   document as there are already specifications for both ISIS
   [I-D.previdi-isis-segment-routing-extensions] and OSPF
   [I-D.psenak-ospf-segment-routing-extensions] protocols describing the
   required extensions.  The existing IGP protocol specifications can be
   very easily extended with a new flag indicating support for Domain
   Wide Label Indicator.

4.  Data plane

   The processing of MPLS packets already supports the notion of context
   labels, recognizing and processing the reserved label space or both.
   Redirection for lookup to separate LFIB table has also been supported
   already by number of platforms mainly for efficient protection and
   restoration applications.

   In one of the application called Segment Routing the LER performing
   the imposition may require multiple transport labels to be imposed on
   the packet each indicating the segment to be traversed.  The LSR
   (often a PHP node, but also gateway between Domain Wide labels and
   traditional/legacy label distribution protocols) which preforms the
   POP of the last Domain Wide transport Label *as determined by the
   control plane signalling* MUST also strip Domain Wide Label Indicator



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   before passing the remaining of the label stack (possibly containing
   application labels) to other components or to other peers.

5.  Advantages

   This document provides ability to explicitly signal the notion of
   Domain Wide Labels carried in the MPLS header of the packets.  The
   main objective is to simplify forwarding planes of LSRs to perform
   lookup based forwarding without additional label swap actions
   therefore further contributing to cost reduction, and increase of
   speed and port density.  Such technique is equally applicable to
   traditional routers as well as to new class of emerging forwarding
   devices where FIBs or LFIBs are programmed remotely by centralized or
   semi-centralized entities.

   While this memo solely focuses on transport labels the notion of
   domain wide labels can also be found applicable to application
   labels.  It is however out of scope of this document.

6.  Deployment considerations

   There are no new deployment requirements introduced by this document.
   The ability to recognize support of domain wide label is to be
   embedded within the specifications defining protocol extensions used
   for signalling of domain wide labels.

7.  Security considerations

   No new security issues are introduced by this specification.  There
   is also no operator configuration or risk of misconfiguration
   introduced by this specification.

8.  IANA Considerations

   IANA is requested to allocate a new reserved space MPLS label value
   to be used as MPLS Domain Wide Label Indicator.

9.  Acknowledgments

   TBD

10.  References

10.1.  Normative References

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




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   [RFC3031]  Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
              Label Switching Architecture", RFC 3031, January 2001.

   [RFC3032]  Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y.,
              Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack
              Encoding", RFC 3032, January 2001.

   [RFC5331]  Aggarwal, R., Rekhter, Y., and E. Rosen, "MPLS Upstream
              Label Assignment and Context-Specific Label Space", RFC
              5331, August 2008.

10.2.  Informative References

   [I-D.filsfils-rtgwg-segment-routing]
              Filsfils, C., Previdi, S., Bashandy, A., Decraene, B.,
              Litkowski, S., Horneffer, M., Milojevic, I., Shakir, R.,
              Ytti, S., Henderickx, W., Tantsura, J., and E. Crabbe,
              "Segment Routing Architecture", draft-filsfils-rtgwg-
              segment-routing-01 (work in progress), October 2013.

   [I-D.gredler-rtgwg-igp-label-advertisement]
              Gredler, H., Amante, S., Scholl, T., and L. Jalil,
              "Advertising MPLS labels in IGPs", draft-gredler-rtgwg-
              igp-label-advertisement-05 (work in progress), May 2013.

   [I-D.minto-2547-egress-node-fast-protection]
              Jeganathan, J., Gredler, H., and B. Decraene, "2547 egress
              PE Fast Failure Protection", draft-minto-2547-egress-node-
              fast-protection-02 (work in progress), July 2013.

   [I-D.previdi-isis-segment-routing-extensions]
              Previdi, S., Filsfils, C., Bashandy, A., Gredler, H., and
              S. Litkowski, "IS-IS Extensions for Segment Routing",
              draft-previdi-isis-segment-routing-extensions-04 (work in
              progress), October 2013.

   [I-D.psenak-ospf-segment-routing-extensions]
              Psenak, P., Previdi, S., Filsfils, C., Gredler, H.,
              Shakir, R., and W. Henderickx, "OSPF Extensions for
              Segment Routing", draft-psenak-ospf-segment-routing-
              extensions-03 (work in progress), October 2013.

   [I-D.sivabalan-pce-segment-routing]
              Sivabalan, S., Medved, J., Filsfils, C., Crabbe, E., and
              R. Raszuk, "PCEP Extensions for Segment Routing", draft-
              sivabalan-pce-segment-routing-02 (work in progress),
              October 2013.




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   [RFC4761]  Kompella, K. and Y. Rekhter, "Virtual Private LAN Service
              (VPLS) Using BGP for Auto-Discovery and Signaling", RFC
              4761, January 2007.

Author's Address

   Robert Raszuk
   NTT I3
   101 S Ellsworth Avenue Suite 350
   San Mateo, CA  94401
   US

   Email: robert@raszuk.net






































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