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Versions: 00 01 02 draft-ietf-manet-olsrv2-multipath

Network Working Group                                              J. Yi
Internet-Draft                                  LIX, Ecole Polytechnique
Intended status: Experimental                                 B. Parrein
Expires: January 30, 2015                           University of Nantes
                                                           July 29, 2014


   Multi-path Extension for the Optimized Link State Routing Protocol
                           version 2 (OLSRv2)
                   draft-yi-manet-olsrv2-multipath-02

Abstract

   This document specifies a multi-path extension to the Optimized Link
   State Routing Protocol version 2 (OLSRv2) to discover multiple
   disjoint paths, so as to improve reliability of the OLSRv2 protocol.
   The interoperability with OLSRv2 is retained.

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
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   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 January 30, 2015.

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
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   (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



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   described in the Simplified BSD License.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Motivation and Experiments to Be Conducted . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  5
   3.  Applicability Statement  . . . . . . . . . . . . . . . . . . .  5
   4.  Protocol Overview and Functioning  . . . . . . . . . . . . . .  6
   5.  Parameters and Constants . . . . . . . . . . . . . . . . . . .  6
     5.1.  Router Parameters  . . . . . . . . . . . . . . . . . . . .  6
   6.  Packets and Messages . . . . . . . . . . . . . . . . . . . . .  7
     6.1.  HELLO and TC messages  . . . . . . . . . . . . . . . . . .  7
       6.1.1.  MP_OLSRv2 TLV  . . . . . . . . . . . . . . . . . . . .  7
     6.2.  Datagram . . . . . . . . . . . . . . . . . . . . . . . . .  7
       6.2.1.  Source Routing Header in IPv4  . . . . . . . . . . . .  7
       6.2.2.  Source Routing Header in IPv6  . . . . . . . . . . . .  8
   7.  Information Bases  . . . . . . . . . . . . . . . . . . . . . .  8
     7.1.  MP-OLSRv2 Router Set . . . . . . . . . . . . . . . . . . .  8
     7.2.  Multi-path Routing Set . . . . . . . . . . . . . . . . . .  8
   8.  Protocol Details . . . . . . . . . . . . . . . . . . . . . . .  9
     8.1.  HELLO and TC Message Generation  . . . . . . . . . . . . .  9
     8.2.  HELLO and TC Message Processing  . . . . . . . . . . . . .  9
     8.3.  Datagram Processing at the MP-OLSRv2 Originator  . . . . . 10
     8.4.  Multi-path Dijkstra Algorithm  . . . . . . . . . . . . . . 10
     8.5.  Datagram Forwarding  . . . . . . . . . . . . . . . . . . . 11
   9.  Configuration Parameters . . . . . . . . . . . . . . . . . . . 12
   10. Implementation Status  . . . . . . . . . . . . . . . . . . . . 12
     10.1. Multi-path extension based on nOLSRv2  . . . . . . . . . . 13
     10.2. Multi-path extension based on olsrd  . . . . . . . . . . . 13
     10.3. Multi-path extension based on umOLSR . . . . . . . . . . . 13
   11. Security Considerations  . . . . . . . . . . . . . . . . . . . 14
   12. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 14
     12.1. HELLO Message-Type-Specific TLV Type Registries  . . . . . 14
     12.2. TC Message-Type-Specific TLV Type Registries . . . . . . . 14
   13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15
     13.1. Normative References . . . . . . . . . . . . . . . . . . . 15
     13.2. Informative References . . . . . . . . . . . . . . . . . . 15
   Appendix A.  An example of Multi-path Dijkstra Algorithm . . . . . 16
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17










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1.  Introduction

   The Optimized Link State Routing Protocol version 2 (OLSRv2)
   [RFC7181] is a proactive link state protocol designed for use in
   mobile ad hoc networks (MANETs).  It generates routing messages
   periodically to create and maintain a Routing Set, which contains
   routing information to all the possible destinations in the routing
   domain.  For each destination, there exists an unique Routing Tuple,
   which indicates the next hop to reach the destination.

   This document specifies an extension of the OLSRv2 protocol
   [RFC7181], to provide multiple disjoint paths for a source-
   destination pair.  Because of the characteristics of MANETs
   [RFC2501], especially the dynamic topology, having multiple paths is
   helpful for increasing network throughput, improving transmission
   reliability and load balancing.

   The Multi-path OLSRv2 (MP-OLSRv2) specified in this document uses
   multi-path Dijkstra algorithm to explore multiple disjoint paths from
   source to the destination based on the topology information obtained
   through OLSRv2, and forward the datagrams in a load-balancing manner
   using source routing.  MP-OLSRv2 is designed to be interoperable with
   OLSRv2.

1.1.  Motivation and Experiments to Be Conducted

   This document is an experimental extension of OLSRv2 that can
   increase the data forwarding reliability in dynamic and high-load
   MANET scenarios by transmitting packet over multiple disjoint paths
   using source routing.  This mechanism is used because:

   o  Disjoint paths can avoid single route failure.

   o  By having control of that paths at the source, the delay can be
      provisioned.

   o  Certain scenarios require some routers must (or must not) be used.

   o  An very important application of this extension is combination
      with Forward Error Correction coding.  This requires disjoint
      paths.  The single path routing is not adapted because the packet
      drop is normally continuous, in which forward correction coding is
      not helpful.

   While existed deployments, running code and simulations have proven
   the interest of multipath extension for OLSRv2 in certain networks,
   more experiments and experiences are still needed to understand the
   mechanisms of the protocol.  The multipath extension for OLSRv2 is



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   expected to be revised and improved to the Standard Track, once
   sufficient operational experience is obtained.  Other than the
   general experiences including the protocol specification,
   interoperability with original OLSRv2 implementations, the
   experiences in the following aspects are highly appreciated:

   o  Optimal values for the number of multiple paths (NUMBER_OF_PATHS)
      to be used.  This depends on the network topology and router
      density.

   o  Optimal values for the cost functions.  Cost functions are applied
      to punish the costs of used links and nodes so as to obtain
      disjoint paths.  What kind of disjointness is desired (node-
      disjoint or link-disjoint) may depends on the layer 2 protocol
      used, and can be achieved by setting different sets of cost
      functions.

   o  Optimal choice of "key" routers for loose source routing.  In some
      cases, loose source routing is use to reduce overhead or for
      interoperability with OLSRv2.  Other than the basic rules defined
      in the following of this document, optimal choices of routers to
      put in the source routing header can be further studied.

   o  Use of other metric other than hop-count.  This multipath
      extension can be used not only for hop-count metric type, but
      other metric types that meet the requirement of OLSRv2, such as
      [I-D.ietf-manet-olsrv2-dat-metric].  The metric type used has also
      co-relation with the choice of cost functions as indicated in the
      previous bullet.

   o  The impacts to the delay variation due to multi-path routing.
      [RFC2991] brings out some concerns of multi-path routing,
      especially variable latencies.  Although current experiments
      result show that multi-path routing can reduce the jitter in
      dynamic scenarios, some transport protocols or applications may be
      sensitive to the packet re-ordering.

   o  The disjoint multiple path protocol has interesting application
      with Forward Error Correction (FEC) Coding, especially for
      services like video/audio streaming.  The combination of FEC
      coding mechanisms and this extension is thus encouraged.

   o  In addition to IP source routing based approach, it can be
      interesting to try multi-path routing in MANET using label-
      switched flow in the future.

   o  The usage of multi-topology information.  By using
      [I-D.ietf-manet-olsrv2-multitopology], multiple topologies using



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      different metric types can be obtained.  It is encouraged to
      experiment the use of multiple metrics for building multiple paths
      also.


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].

   This document uses the terminology and notation defined in [RFC5444],
   [RFC6130], [RFC7181].  Additionally, it defines the following
   terminology:

   OLSRv2 Routing Process -  The routing process based on [RFC7181],
      without multi-path extension specified in this document.

   MP-OLSRv2 Routing Process -  The routing process based on this
      specification as an extension to [RFC7181].


3.  Applicability Statement

   As an extension of OLSRv2, this specification is applicable to MANETs
   for which OLSRv2 is applicable (see [RFC7181]).  It can operate on
   single, or multiple interfaces, to discover multiple disjoint paths
   from a source router to a destination router.

   MP-OLSRv2 is specially designed for networks with dynamic topology
   and slow data rate links.  By providing multiple paths, higher
   aggregated bandwidth can be obtained, and the routing process is more
   robust to packet loss.

   In a router supporting MP-OLSRv2, MP-OLSRv2 does not necessarily
   replace OLSRv2 completely.  The extension can be applied for certain
   applications that are suitable for multi-path routing (mainly video
   or audio streams), based on the information such as DiifServ Code
   Point [RFC2474].

   Compared to OLSRv2, this extension does not introduce new message
   type in the air, and is interoperable with OLSRv2 implementations
   that do not have this extension.







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4.  Protocol Overview and Functioning

   This specification requires OLSRv2 [RFC7181] to:

   o  Identify all the reachable routers in the network.

   o  Identify a sufficient subset of links in the networks, so that
      routes can be calculated to all reachable destinations.

   o  Provide a Routing Set containing shortest routes from this router
      to all destinations.

   Based on the above information acquired by OLSRv2, the MP-OLSRv2
   Routing Process is able to calculate multiple paths to certain
   destinations based on multi-path Dijkstra algorithm: the Dijkstra
   algorithm is performed multiple times .  In each iteration, the cost
   of used links are increased (i.e., punished), so that they can be
   avoided to be chosen in the next iteration.  The multi-path Dijkstra
   algorithm can generate multiple disjoint paths from a source to a
   destination , and such information is kept in Multi-path Routing Set.
   The algorithm is invoked on demand, i.e., only when there is data
   traffic to be sent from the source to the destination, and there is
   no available routing tuples in the Multi-path Routing Set.

   The datagram is forwarded based on source routing.  When there is a
   datagram to be sent to a destination, the source router acquires a
   path from the Multi-path Routing Set (in Round-Robin fashion here) .
   The path information is stored in the datagram header as source
   routing header.  The intermediate routers listed in the source
   routing header (SRH) read the SRH and forward the datagram to the
   next hop indicated in the SRH.


5.  Parameters and Constants

   In addition to the parameters and constants defined in [RFC7181],
   this specification uses the parameters and constants described in
   this section.

5.1.  Router Parameters

   NUMBER_OF_PATHS   The number of paths desired by the router.

   MAX_SRC_HOPS   The maximum number of hops allowed to put in the
      source routing header.






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   fp   Incremental function of multi-path Dijkstra algorithm.  It is
      used to increase costs of links belonging to the previously
      computed path.

   fe   Incremental function of multi-path Dijkstra algorithm.  It is
      used to increase costs of links who lead to routers of the
      previous computed path.

   MR_HOLD_TIME  It is the minimal time that a Multi-path Routing Tuple
      SHOULD be kept in the Multi-path Routing Set.

   MP_OLSR_HOLD_TIME  It is the minimal time that a MP-OLSRv2 Router
      Tuple SHOULD be kept in the MP-OLSRv2 Router Set.


6.  Packets and Messages

   This extension employs the routing control messages HELLO and TC
   (Topology Control) as defined in OLSRv2 [RFC7181].  To support source
   routing, a source routing header is added to each datagram routed by
   this extension.  Depending on the IP version used, the source routing
   header is defined in following of this section.

6.1.  HELLO and TC messages

   HELLO and TC messages used by MP-OLSRv2 Routing Process share the
   same format as defined in [RFC7181].  In addition, one Message TLV is
   defined, to identify the originator of the HELLO or TC message is
   running MP-OLSRv2.

6.1.1.  MP_OLSRv2 TLV

   An MP_OLSRv2 TLV is a Message TLV that signals the message is
   generated by an MP-OLSRv2 Routing Process.  It does not include any
   value.

   Every HELLO or TC message generated by MP-OLSRv2 Routing Process MUST
   has one MP_OLSRv2 TLV.

6.2.  Datagram

6.2.1.  Source Routing Header in IPv4

   In IPv4 [RFC0791] networks, the MP-OLSRv2 routing process employs
   loose source routing, as defined in [RFC0791].  It exists as an
   option header, with option class 0, and option number 3.

   The source route information is kept in the "route data" field of the



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   loss source route header.

6.2.2.  Source Routing Header in IPv6

   In IPv6 [RFC2460] networks, the MP-OLSRv2 routing process employs the
   source routing header as defined in [RFC6554], with IPv6 Routing Type
   3.

   The source route information is kept in the "Addresses" field of the
   routing header.


7.  Information Bases

   Each MP-OLSRv2 routing process maintains the information bases as
   defined in [RFC7181].  Additionally, two more information bases are
   defined for this specification.

7.1.  MP-OLSRv2 Router Set

   The MP-OLSRv2 Router Set recordes the routers running the MP-OLSRv2
   Routing Process.  It consists of MP-OLSRv2 Router Tuples:

   (MP_OLSR_addr, MP_OLSR_valid_time)

   where:

   MP_OLSR_addr -   it is the network address of the router that runs
      MP-OLSRv2 Routing Process;

   MP_OLSR_valid_time -   it is the time until which the MP-OLSRv2
      Router Tuples is considered valid.

7.2.  Multi-path Routing Set

   The Multi-path Routing Set records the full path information of
   different paths to the destination.  It consists of Multi-path
   Routing Tuples:

   (MR_dest_addr, MR_valid_time, MR_path_set)

   where:

   MR_dest_addr -   it is the network address of the destination, either
      the network address of an interface of a destination router or the
      network address of an attached network;





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   MR_valid_time -   it is the time until which the Multi-path Routing
      Tuples is considered valid;

   MP_path_set -   it contains the multiple paths to the destination.
      It consists of Path Tuples.

   Each Path Tuple is defined as:

   (PT_cost, PT_address[1], PT_address[2], ..., PT_address[n])

   where:

   PT_cost -   the cost of the path to the destination;

   PT_address[1...n] -   the addresses of intermediate router to be
      visited numbered from 1 to n.


8.  Protocol Details

   This protocol is based on OLSRv2, and extended to discover multiple
   disjoint paths from the source to the destination router.  It retains
   the basic routing control packets formats and processing of OLSRv2 to
   obtain topology information of the network.  The main differences
   between OLSRv2 routing process is the datagram processing at the
   source router and datagram forwarding.

8.1.  HELLO and TC Message Generation

   HELLO and TC messages are generated according to the section 15.1 or
   section 16.1 of [RFC7181].

   A single Message-Type-Specific TLV with Type := MP_OLSRv2 is added to
   the message.

8.2.  HELLO and TC Message Processing

   HELLO and TC messages are processed according to the section 15.3 and
   16.3 of [RFC7181].

   For every HELLO or TC message received, if there exists a TLV with
   Type := MP_OLSRv2, create or update (if the tuple exists already) the
   MP-OLSR Router Tuple with

   o  MP_OLSR_addr = originator of the HELLO or TC message

   and set the MP_OLSR_valid_time := current_time + MP_OLSR_HOLD_TIME.




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8.3.  Datagram Processing at the MP-OLSRv2 Originator

   When the MP-OLSRv2 routing process receives a datagram from upper
   layers or interfaces connecting other routing domains, find the
   Multi-path Routing Tuple where:

   o  MR_dest_addr = destination of the datagram, and

   o  MR_valid_time < current_time.

   If a matching Multi-path Routing Tuple is found, a Path Tuple is
   chosen from the MR_path_set in Round-robin fashion (if there are
   multiple datagrams to be sent).  Or else, the Multi-path Dijkstra
   Algorithm defined in Section 8.4 is invoked, to generate the desired
   Multi-path Routing Tuple.

   The addresses in PT_address[1...n] of the chosen Path Tuple are thus
   added to the datagram header in order as source routing header,
   following the rules:

   o  Only the addresses exist in MP-OLSR Router Set can be added to the
      source routing header.

   o  If the length of the path (n) is greater than MAX_SRC_HOPS, only
      the key routers in the path are kept.  By default, the key routers
      are uniformly chosen in the path.

   o  The routers with higher priority (such as higher willingness of
      routing) are preferred.

   o  The routers that are considered not appropriate for forwarding
      indicated by external policies should be avoided.

8.4.  Multi-path Dijkstra Algorithm

   The Multi-path Dijkstra Algorithm is invoked when there is no
   available Multi-path Routing Tuple to a desired destination d.  The
   general principle of the algorithm is at step i to look for the
   shortest path Pi to the destination d.  Based on Dijkstra algorithm,
   the main modification consists in adding two cost functions namely
   incremental functions fp and fe in order to prevent the next steps to
   use similar path. fp is used to increase costs of arcs belonging to
   the previously path Pi (or which opposite arcs belong to it).  This
   encourages future paths to use different arcs but not different
   vertices. fe is used to increase costs of the arcs who lead to
   vertices of the previous path Pi.  It is possible to choose different
   fp and fe to get link-disjoint path or node-disjoint routes as
   necessary.  A recommendation of configuration of fp and fe is given



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   in Section 5.

   To get NUMBER_OF_PATHS distinct paths, for each path Pi (i = 1, ...,
   NUMBER_OF_PATHS) do:

   1.  Run Dijkstra algorithm to get the shortest path Pi for the
       destination d.

   2.  Apply cost function fp to the links in Pi.

   3.  Apply cost function fe to the links who lead to routers used in
       P.

   A simple example of Multi-path Dijkstra Algorithm is illustrated in
   Appendix A.

   By invoking the algorithm depicted above, NUMBER_OF_PATHS distinct
   paths is obtained, and added to the Multi-path Routing Set, by
   creating a Multi-path Routing Tuple with:

   o  MR_dest_addr := destination d

   o  MR_valid_time := current time + MR_HOLD_TIME

   o  Each Path Tuple in the MP_path_set corresponds to a path obtained
      in multi-path Dijkstra algorithm, with PT_cost := cost of the path
      to the destination d.

8.5.  Datagram Forwarding

   On receiving a datagram with source routing header, the Destination
   Address field of the IP header is first compared to the addresses of
   the local interfaces.  If no matching address is found, the datagram
   is forwarded according OLSRv2 routing process.  If a matching local
   address if found, the datagram is processed as follows:

   1.  Obtain the next source address Address[i] in the source route
       header.  How to obtain the next source address depends on the IP
       version used.  In IPv4, the position of the next source address
       is indicated by the "pointer" field of the source routing header
       [RFC0791].  In IPv6, the position is indicated by "Segments Left"
       field of the source routing header.  If no next source address is
       found, the forwarding process is finished.

   2.  Swap Address[i] and destination address in the IP header.

   3.  Forward the datagram to the destination address according to the
       OLSRv2 Routing Tuple information through R_local_iface_addr where



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       *  R_dest_addr = destination address in the IP header


9.  Configuration Parameters

   This section gives default values and guideline for setting
   parameters defined in Section 5.  Network administrator may wish to
   change certain, or all the parameters for different network
   scenarios.  As an experimental track protocol, the users of this
   protocol are also encouraged to explore different parameter setting
   in various network environments, and provide feedback.

   o  NUMBER_OF_PATHS = 3.  This parameter defines the number of
      parallel paths used in datagram forwarding.  Setting it to one
      makes the specification identical to OLSRv2.  Setting it to too
      big value can lead to unnecessary computational overhead and
      inferior paths.

   o  MAX_SRC_HOPS = 10.

   o  MR_HOLD_TIME = 10 seconds.

   o  fp(c) = 4*c, where c is the original cost of the link.

   o  fe(c) = 2*c, where c is the original cost of the link.

   The setting of cost functions fp and fc defines the preference of
   obtained multiple disjoint paths.  If id is the identity functions, 3
   cases are possible:

   o  if id=fe<fp paths tend to be link disjoint;

   o  if id<fe=fp paths tend to be node-disjoint;

   o  if id<fe<fp paths also tend to be node-disjoint, but when is not
      possible they tend to be arc disjoint.


10.  Implementation Status

   This section records the status of known implementations of the
   protocol defined by this specification at the time of posting of this
   Internet-Draft, and based on a proposal described in [RFC6982].  The
   description of implementations in this section is intended to assist
   the IETF in its decision processes in progressing drafts to RFCs.
   Please note that the listing of any individual implementation here
   does not imply endorsement by the IETF.  Furthermore, no effort has
   been spent to verify the information presented here that was supplied



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   by IETF contributors.  This is not intended as, and must not be
   construed to be, a catalog of available implementations or their
   features.  Readers are advised to note that other implementations may
   exist.

   According to [RFC6982], "this will allow reviewers and working groups
   to assign due consideration to documents that have the benefit of
   running code, which may serve as evidence of valuable experimentation
   and feedback that have made the implemented protocols more mature.
   It is up to the individual working groups to use this information as
   they see fit".

   Until April 2014, there are 3 open source implementations of the
   protocol specified in this document, for both testbed and simulation
   use.

10.1.  Multi-path extension based on nOLSRv2

   The implementation is conducted by University of Nantes, France, and
   is based on Niigata University's nOLSRv2 implementation.  It is an
   open source implementation.  The code is available at
   http://jiaziyi.com/index.php/research-projects/mp-olsr .

   It can be used for Qualnet simulations, and be exported to run in
   testbed.  All the specification is implemented in this
   implementation.

   Implementation experience and test data can be found at [ADHOC11].

10.2.  Multi-path extension based on olsrd

   The implementation is conducted under SEREADMO (Securite des Reseaux
   Ad Hoc & Mojette) project, and supported by French research agency
   (RNRT2803).  It is based on olsrd (http://www.olsr.org/)
   implementation, and is open sourced.  The code is available at
   http://jiaziyi.com/index.php/research-projects/sereadmo .

   The implementation is for testing the specification in the field.
   All the specification is implemented in this implementation.

   Implementation experience and test data can be found at [ADHOC11].

10.3.  Multi-path extension based on umOLSR

   The implementation is conducted by University of Nantes, France, and
   is based on um-olsr implementation
   (http://masimum.inf.um.es/fjrm/development/um-olsr/).  The code is
   available at http://jiaziyi.com/index.php/research-projects/mp-olsr



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   under GNU GPL license.

   The implementation is just for network simulation for NS2 network
   simulator.  All the specification is implemented in this
   implementation.

   Implementation experience and test data can be found at [WCNC08].


11.  Security Considerations

   This document does currently not specify any security
   considerations....


12.  IANA Considerations

   This specification defines two Message TLV Types, which must be
   allocated from the Message TLV Types repository of [RFC5444].

12.1.  HELLO Message-Type-Specific TLV Type Registries

   IANA is requested to create a registry for Message-Type-Specific
   Message TLV for HELLO messages, in accordance with Section 6.2.1 of
   [RFC5444], and with initial assignments and allocation policies as
   specified in Table 1.

               +---------+-------------+-------------------+
               |   Type  | Description | Allocation Policy |
               +---------+-------------+-------------------+
               |   128   | MP_OLSRv2   |                   |
               | 129-223 | Unassigned  | Expert Review     |
               +---------+-------------+-------------------+

          Table 1: HELLO Message-Type-specific Message TLV Types

12.2.  TC Message-Type-Specific TLV Type Registries

   IANA is requested to create a registry for Message-Type-Specific
   Message TLV for TC messages, in accordance with Section 6.2.1 of
   [RFC5444], and with initial assignments and allocation policies as
   specified in Table 2.









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               +---------+-------------+-------------------+
               |   Type  | Description | Allocation Policy |
               +---------+-------------+-------------------+
               |   128   | MP_OLSRv2   |                   |
               | 129-223 | Unassigned  | Expert Review     |
               +---------+-------------+-------------------+

            Table 2: TC Message-Type-specific Message TLV Types


13.  References

13.1.  Normative References

   [RFC0791]  Postel, J., "Internet Protocol", STD 5, RFC 791,
              September 1981.

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

   [RFC5444]  Clausen, T., Dearlove, C., Dean, J., and C. Adjih,
              "Generalized Mobile Ad Hoc Network (MANET) Packet/Message
              Format", RFC 5444, February 2009.

   [RFC6130]  Clausen, T., Dearlove, C., and J. Dean, "Mobile Ad Hoc
              Network (MANET) Neighborhood Discovery Protocol (NHDP)",
              RFC 6130, April 2011.

   [RFC6554]  Hui, J., Vasseur, JP., Culler, D., and V. Manral, "An IPv6
              Routing Header for Source Routes with the Routing Protocol
              for Low-Power and Lossy Networks (RPL)", RFC 6554,
              March 2012.

   [RFC7181]  Clausen, T., Dearlove, C., Jacquet, P., and U. Herberg,
              "The Optimized Link State Routing Protocol Version 2",
              RFC 7181, April 2014.

13.2.  Informative References

   [ADHOC11]  Yi, J., Adnane, A-H., David, S., and B. Parrein,
              "Multipath optimized link state routing for mobile ad hoc
              networks", In Elsevier Ad Hoc Journal, vol.9, n. 1, 28-47,
              January, 2011.

   [I-D.ietf-manet-olsrv2-dat-metric]
              Rogge, H. and E. Baccelli, "Packet Sequence Number based
              directional airtime metric for OLSRv2",
              draft-ietf-manet-olsrv2-dat-metric-01 (work in progress),



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              July 2014.

   [I-D.ietf-manet-olsrv2-multitopology]
              Dearlove, C. and T. Clausen, "Multi-Topology Extension for
              the Optimized Link State Routing Protocol version 2
              (OLSRv2)", draft-ietf-manet-olsrv2-multitopology-04 (work
              in progress), July 2014.

   [RFC2460]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", RFC 2460, December 1998.

   [RFC2474]  Nichols, K., Blake, S., Baker, F., and D. Black,
              "Definition of the Differentiated Services Field (DS
              Field) in the IPv4 and IPv6 Headers", RFC 2474,
              December 1998.

   [RFC2501]  Corson, M. and J. Macker, "Mobile Ad hoc Networking
              (MANET): Routing Protocol Performance Issues and
              Evaluation Considerations", RFC 2501, January 1999.

   [RFC2991]  Thaler, D. and C. Hopps, "Multipath Issues in Unicast and
              Multicast Next-Hop Selection", RFC 2991, November 2000.

   [RFC6982]  Sheffer, Y. and A. Farrel, "Improving Awareness of Running
              Code: The Implementation Status Section", RFC 6982,
              July 2013.

   [WCNC08]   Yi, J., Cizeron, E., Hamma, S., and B. Parrein,
              "Simulation and performance analysis of MP-OLSR for mobile
              ad hoc networks", In Proceeding of IEEE Wireless
              Communications and Networking Conference, 2008.


Appendix A.  An example of Multi-path Dijkstra Algorithm

   This appendix gives an example of multi-path Dijkstra algorithm.  The
   network topology is depicted in Figure 1.

                               .-----2-----.
                              /     / \     \
                             /     /   \     \
                            1     /     \     5
                             \   /       \   /
                              \ /         \ /
                               3-----------4


           Figure 1: Network Topology for the on-demand example



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   The initial cost of all the links is set to 1.  The incremental
   functions fp and fe are defined as fp(c)=4c and fe(c)=2c in this
   example.  Two routes from node 1 to node 5 are demanded.

   On the first run of the Dijkstra algorithm, the shortest path 1->2->5
   with cost 2 is obtained.

   The incremental function fp is applied to increase the cost of the
   link 1-2 and 2-5, from 1 to 4. fe is applied to increase the cost of
   the link 1-3, 2-3, 2-4, 4-5, from 1 to 2.

   On the second run of the Dijkstra algorithm, the second path
   1->3->4->5 with cost 5 is obtained.


Authors' Addresses

   Jiazi Yi
   LIX, Ecole Polytechnique
   91128 Palaiseau Cedex,
   France

   Phone: +33 1 77 57 80 85
   Email: jiazi@jiaziyi.com
   URI:   http://www.jiaziyi.com/


   Benoit Parrein
   University of Nantes
   IRCCyN lab - IVC team
   Polytech Nantes, rue Christian Pauc, BP50609
   44306 Nantes cedex 3
   France

   Phone: +33 (0) 240 683 050
   Email: Benoit.Parrein@polytech.univ-nantes.fr
   URI:   http://www.irccyn.ec-nantes.fr/~parrein














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