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rfc:rfc7187

Internet Engineering Task Force (IETF) C. Dearlove Request for Comments: 7187 BAE Systems ATC Updates: 7181 T. Clausen Category: Standards Track LIX, Ecole Polytechnique ISSN: 2070-1721 April 2014

             Routing Multipoint Relay Optimization for
    the Optimized Link State Routing Protocol Version 2 (OLSRv2)

Abstract

 This specification updates the Optimized Link State Routing Protocol
 version 2 (OLSRv2) with an optimization to improve the selection of
 routing multipoint relays.  The optimization retains full
 interoperability between implementations of OLSRv2 with and without
 this optimization.

Status of This Memo

 This is an Internet Standards Track document.
 This document is a product of the Internet Engineering Task Force
 (IETF).  It represents the consensus of the IETF community.  It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG).  Further information on
 Internet Standards is available in Section 2 of RFC 5741.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc7187.

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
 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.

Dearlove & Clausen Standards Track [Page 1] RFC 7187 OLSRv2 Routing MPR Optimization April 2014

Table of Contents

 1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
 2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
 3.  Applicability Statement . . . . . . . . . . . . . . . . . . .   2
 4.  Routing MPR Selection . . . . . . . . . . . . . . . . . . . .   3
 5.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
 6.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   4
 7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
   7.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
   7.2.  Informative References  . . . . . . . . . . . . . . . . .   4

1. Introduction

 The Optimized Link State Routing Protocol version 2 [RFC7181] is a
 proactive link state routing protocol designed for use in mobile ad
 hoc networks (MANETs) [RFC2501].  This document improves one area of
 the OLSRv2 specification.
 One improvement included in OLSRv2, compared to its predecessor
 described in [RFC3626], is the use of link metrics, rather than
 minimum-hop routing.  A rationale for how link metrics were included
 in OLSRv2 is documented in [RFC7185].  However, one aspect of the use
 of link metrics described in [RFC7185], the removal of some
 unnecessarily selected routing multipoint relays (MPRs), was not
 included in [RFC7181].  This specification updates OLSRv2 to include
 this optimization.
 Note that this optimization does not impact interoperability:
 implementations that do and do not implement this optimization will
 interoperate seamlessly.

2. Terminology

 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
 "OPTIONAL" in this document are to be interpreted as described in
 [RFC2119].
 Additionally, this document uses the terminology of [RFC7181].

3. Applicability Statement

 This specification updates [RFC7181].  As such, it is applicable to
 all implementations of this protocol.  The optimization presented in
 this specification is simply permissive; it allows an additional
 optimization, and there is no requirement for any implementation to

Dearlove & Clausen Standards Track [Page 2] RFC 7187 OLSRv2 Routing MPR Optimization April 2014

 include it.  However, inclusion of this optimization is advised; it
 can, in some cases, create smaller and fewer messages, without ever
 having the opposite effect.
 [RFC7181] defines the properties for the selection of routing MPRs
 from among a router's symmetric 1-hop neighbors.  The properties are
 o  the selected MPRs must consist of a set of symmetric 1-hop
    neighbors that cover all the symmetric 2-hop neighbors, and
 o  the selected MPRs must do so retaining a minimum distance route
    (1-hop, if present, or 2-hop) to each symmetric 2-hop neighbor.
 The discussion in the latter part of Section 6.2 of [RFC7185]
 indicates that this requirement is overly prescriptive for routing
 MPR selection.  The update to [RFC7181] described in this
 specification permits a router to use the described optimization,
 while still being considered compliant with OLSRv2.
 Note that whether or not a router is considered compliant, a router
 that implements the optimization described in this specification will
 interoperate successfully with routers that are not implementing this
 optimization.

4. Routing MPR Selection

 A set of routing MPRs created as specified in [RFC7181] MAY be
 optimized in the following manner.  Note that this uses the notation
 of Section 18.2 of [RFC7181]:
 1.  If there is a sequence x_0, ..., x_n of elements of N1 such that:
  • x_0 is a routing MPR,
  • x_1, … , x_n have corresponding elements y_1, …, y_n of

N2, and

  • d1(x_0) + d2(x_0,y_1) + … + d2(x_m-1,y_m) < d1(x_m) for m =

1, … , n,

     then x_1 to x_n may be removed from the set of routing MPRs, if
     selected.
 Note that "corresponding elements" in N1 and N2 means that these
 elements represent the same router.  All of this information is
 available from information gathered by NHDP [RFC6130].

Dearlove & Clausen Standards Track [Page 3] RFC 7187 OLSRv2 Routing MPR Optimization April 2014

5. Security Considerations

 The update to OLSRv2 [RFC7181] does not introduce any new protocol
 signals, nor does it change the processing of any received protocol
 signals.
 This update to OLSRv2 [RFC7181] permits an implementation that is
 compliant with OLSRv2 to (potentially) eliminate some unneeded
 routers from the routing MPR sets generated as described in
 [RFC7181], which also eliminates the need to include the
 corresponding information in generated Topology Control (TC)
 messages.  Because this information is not used when included, this
 update to OLSRv2 [RFC7181] does not present any additional security
 considerations, beyond those described in [RFC7181].

6. Acknowledgments

 The authors would like to gratefully acknowledge Philippe Jacquet
 (Alcatel-Lucent) for intense technical discussions and comments.

7. References

7.1. Normative References

 [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
            Requirement Levels", BCP 14, RFC 2119, March 1997.
 [RFC6130]  Clausen, T., Dean, J., and C. Dearlove, "Mobile Ad Hoc
            Network (MANET) Neighborhood Discovery Protocol (NHDP)",
            RFC 6130, April 2011.
 [RFC7181]  Clausen, T., Dearlove, C., Jacquet, P., and U. Herberg,
            "The Optimized Link State Routing Protocol Version 2", RFC
            7181, April 2014.

7.2. Informative References

 [RFC2501]  Macker, J. and S. Corson, "Mobile Ad hoc Networking
            (MANET): Routing Protocol Performance Issues and
            Evaluation Considerations", RFC 2501, January 1999.
 [RFC3626]  Clausen, T. and P. Jacquet, "The Optimized Link State
            Routing Protocol", RFC 3626, October 2003.
 [RFC7185]  Clausen, T., Dearlove, C., and P. Jacquet, "Rationale for
            the Use of Link Metrics in the Optimized Link State
            Routing Protocol Version 2 (OLSRv2)", RFC 7185, April
            2014.

Dearlove & Clausen Standards Track [Page 4] RFC 7187 OLSRv2 Routing MPR Optimization April 2014

Authors' Addresses

 Christopher Dearlove
 BAE Systems Advanced Technology Centre
 West Hanningfield Road
 Great Baddow, Chelmsford
 United Kingdom
 Phone: +44 1245 242194
 EMail: chris.dearlove@baesystems.com
 URI:   http://www.baesystems.com/
 Thomas Heide Clausen
 LIX, Ecole Polytechnique
 Phone: +33 6 6058 9349
 EMail: T.Clausen@computer.org
 URI:   http://www.ThomasClausen.org/

Dearlove & Clausen Standards Track [Page 5]

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