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Versions: (draft-clausen-manet-olsrv2) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 19 RFC 7181

Mobile Ad hoc Networking (MANET)                              T. Clausen
Internet-Draft                          LIX, Ecole Polytechnique, France
Expires: September 7, 2006                                   C. Dearlove
                                         BAE Systems Advanced Technology
                                                                  Centre
                                                  The OLSRv2 Design Team
                                                     MANET Working Group
                                                           March 6, 2006


          The Optimized Link-State Routing Protocol version 2
                       draft-ietf-manet-olsrv2-01

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Copyright Notice

   Copyright (C) The Internet Society (2006).

Abstract

   This document describes version 2 of the Optimized Link State Routing
   (OLSRv2) protocol for mobile ad hoc networks.  The protocol is an
   optimization of the classical link state algorithm tailored to the
   requirements of a mobile wireless LAN.



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   The key optimization of OLSRv2 is that of multipoint relays,
   providing an efficient mechanism for network-wide broadcast of link-
   state information.  A secondary optimization is, that OLSRv2 employs
   partial link-state information: each node maintains information of
   all destinations, but only a subset of links.  This allows that only
   select nodes diffuse link-state advertisements (i.e. reduces the
   number of network-wide broadcasts) and that these advertisements
   contain only a subset of links (i.e. reduces the size of each
   network-wide broadcast).  The partial link-state information thus
   obtained allows each OLSRv2 node to at all times maintain optimal (in
   terms of number of hops) routes to all destinations in the network.

   OLSRv2 imposes minimum requirements to the network by not requiring
   sequenced or reliable transmission of control traffic.  Furthermore,
   the only interaction between OLSRv2 and the IP stack is routing table
   management.

   OLSRv2 is particularly suitable for large and dense networks as the
   technique of MPRs works well in this context.
































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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  5
     1.1   Terminology  . . . . . . . . . . . . . . . . . . . . . . .  6
     1.2   Applicability Statement  . . . . . . . . . . . . . . . . .  7
   2.  Protocol Overview and Functioning  . . . . . . . . . . . . . .  9
     2.1   Protocol Extensibility . . . . . . . . . . . . . . . . . . 11
   3.  Processing and Forwarding Repositories . . . . . . . . . . . . 13
     3.1   Received Message Set . . . . . . . . . . . . . . . . . . . 13
     3.2   Fragment Set . . . . . . . . . . . . . . . . . . . . . . . 13
     3.3   Processed Set  . . . . . . . . . . . . . . . . . . . . . . 14
     3.4   Forwarded Set  . . . . . . . . . . . . . . . . . . . . . . 14
     3.5   Relay Set  . . . . . . . . . . . . . . . . . . . . . . . . 14
   4.  Packet Processing and Message Forwarding . . . . . . . . . . . 16
     4.1   Actions when Receiving an OLSRv2 Packet  . . . . . . . . . 16
     4.2   Actions when Receiving an OLSRv2 Message . . . . . . . . . 16
     4.3   Message Considered for Processing  . . . . . . . . . . . . 16
     4.4   Message Considered for Forwarding  . . . . . . . . . . . . 18
   5.  Information Repositories . . . . . . . . . . . . . . . . . . . 21
     5.1   Neighborhood Information Base  . . . . . . . . . . . . . . 21
       5.1.1   Link Set . . . . . . . . . . . . . . . . . . . . . . . 21
       5.1.2   2-Hop Neighbor Set . . . . . . . . . . . . . . . . . . 22
       5.1.3   Neighborhood Address Association Set . . . . . . . . . 23
       5.1.4   MPR Set  . . . . . . . . . . . . . . . . . . . . . . . 23
       5.1.5   MPR Selector Set . . . . . . . . . . . . . . . . . . . 23
       5.1.6   Advertised Neighbor Set  . . . . . . . . . . . . . . . 23
     5.2   Topology Information Base  . . . . . . . . . . . . . . . . 24
       5.2.1   Topology Set . . . . . . . . . . . . . . . . . . . . . 24
       5.2.2   Attached Network Set . . . . . . . . . . . . . . . . . 24
       5.2.3   Routing Set  . . . . . . . . . . . . . . . . . . . . . 25
   6.  OLSRv2 Control Message Structures  . . . . . . . . . . . . . . 26
     6.1   General OLSRv2 Message TLVs  . . . . . . . . . . . . . . . 26
       6.1.1   VALIDITY_TIME TLV  . . . . . . . . . . . . . . . . . . 26
       6.1.2   INTERVAL_TIME TLV  . . . . . . . . . . . . . . . . . . 27
     6.2   Local Interface Blocks . . . . . . . . . . . . . . . . . . 28
     6.3   HELLO Messages . . . . . . . . . . . . . . . . . . . . . . 28
       6.3.1   HELLO Message: Message TLVs  . . . . . . . . . . . . . 29
       6.3.2   HELLO Message: Address Blocks TLVs . . . . . . . . . . 29
     6.4   TC Messages  . . . . . . . . . . . . . . . . . . . . . . . 30
   7.  HELLO Message Generation . . . . . . . . . . . . . . . . . . . 31
     7.1   HELLO Message: Transmission  . . . . . . . . . . . . . . . 33
   8.  HELLO Message Processing . . . . . . . . . . . . . . . . . . . 34
     8.1   Populating the Link Set  . . . . . . . . . . . . . . . . . 34
     8.2   Populating the 2-Hop Neighbor Set  . . . . . . . . . . . . 36
     8.3   Populating the MPR Selector Set  . . . . . . . . . . . . . 37
     8.4   Neighborhood and 2-Hop Neighborhood Changes  . . . . . . . 38
   9.  TC Message Generation  . . . . . . . . . . . . . . . . . . . . 40
     9.1   TC Message: Transmission . . . . . . . . . . . . . . . . . 41



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   10.   TC Message Processing  . . . . . . . . . . . . . . . . . . . 42
     10.1  Checking Freshness & Validity of a TC message  . . . . . . 42
     10.2  Updating the Topology Set  . . . . . . . . . . . . . . . . 43
     10.3  Purging Old Entries from the Topology Set  . . . . . . . . 44
     10.4  Updating the Attached Networks Set . . . . . . . . . . . . 44
     10.5  Purging Old Entries from the Attached Network Set  . . . . 45
     10.6  Processing Unfragmented TC Messages  . . . . . . . . . . . 45
     10.7  Processing Partially or Wholly Self-Contained
           Fragmented TC Messagess  . . . . . . . . . . . . . . . . . 45
   11.   Populating the MPR Set . . . . . . . . . . . . . . . . . . . 47
   12.   Populating Derived Sets  . . . . . . . . . . . . . . . . . . 48
     12.1  Populating the Relay Set . . . . . . . . . . . . . . . . . 48
     12.2  Populating the Advertised Neighbor Set . . . . . . . . . . 48
   13.   Populating the Neighborhood Address Association Set  . . . . 49
   14.   Routing Table Calculation  . . . . . . . . . . . . . . . . . 50
   15.   Proposed Values for Constants  . . . . . . . . . . . . . . . 53
     15.1  Message Intervals  . . . . . . . . . . . . . . . . . . . . 53
     15.2  Holding Times  . . . . . . . . . . . . . . . . . . . . . . 53
     15.3  Willingness  . . . . . . . . . . . . . . . . . . . . . . . 53
     15.4  Time . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
   16.   Representing Time  . . . . . . . . . . . . . . . . . . . . . 55
   17.   IANA Considerations  . . . . . . . . . . . . . . . . . . . . 56
     17.1  Multicast Addresses  . . . . . . . . . . . . . . . . . . . 56
     17.2  Message Types  . . . . . . . . . . . . . . . . . . . . . . 56
     17.3  TLV Types  . . . . . . . . . . . . . . . . . . . . . . . . 56
   18.   References . . . . . . . . . . . . . . . . . . . . . . . . . 57
       Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 58
   A.  Example Heuristic for Calculating MPRs . . . . . . . . . . . . 59
   B.  Example Algorithms for Generating Control Traffic  . . . . . . 62
     B.1   Example Algorithm for Generating HELLO messages  . . . . . 62
     B.2   Example Algorithm for Generating TC messages . . . . . . . 63
   C.  Protocol and Port Number . . . . . . . . . . . . . . . . . . . 65
   D.  Packet and Message Layout  . . . . . . . . . . . . . . . . . . 66
     D.1   OLSRv2 Packet Format . . . . . . . . . . . . . . . . . . . 66
   E.  Node Configuration . . . . . . . . . . . . . . . . . . . . . . 73
   F.  Security Considerations  . . . . . . . . . . . . . . . . . . . 74
     F.1   Confidentiality  . . . . . . . . . . . . . . . . . . . . . 74
     F.2   Integrity  . . . . . . . . . . . . . . . . . . . . . . . . 74
     F.3   Interaction with External Routing Domains  . . . . . . . . 75
     F.4   Node Identity  . . . . . . . . . . . . . . . . . . . . . . 76
   G.  Flow and Congestion Control  . . . . . . . . . . . . . . . . . 77
   H.  Sequence Numbers . . . . . . . . . . . . . . . . . . . . . . . 78
   I.  Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 79
   J.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 80
       Intellectual Property and Copyright Statements . . . . . . . . 81






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1.  Introduction

   The Optimized Link State Routing Protocol version 2 (OLSRv2) is an
   update to OLSRv1 as published in RFC3626 [1].  Compared to RFC3626,
   OLSRv2 retains the same basic mechanisms and algorithms, while
   providing an even more flexible signaling framework and some
   simplification of the messages being exchanged.  Also, OLSRv2 takes
   care to accomodate both IPv4 and IPv6 addresses in a compact fashion.

   OLSRv2 is developed for mobile ad hoc networks.  It operates as a
   table driven, proactive protocol, i.e. it exchanges topology
   information with other nodes of the network regularly.  Each node
   selects a set of its neighbor nodes as "MultiPoint Relays" (MPRs).
   In OLSRv2, only nodes that are selected as such MPRs are then
   responsible for forwarding control traffic intended for diffusion
   into the entire network.  MPRs provide an efficient mechanism for
   flooding control traffic by reducing the number of transmissions
   required.

   Nodes selected as MPRs also have a special responsibility when
   declaring link state information in the network.  Indeed, the only
   requirement for OLSRv2 to provide shortest path routes to all
   destinations is that MPR nodes declare link-state information for
   their MPR selectors.  Additional available link-state information may
   be utilized, e.g., for redundancy.

   Nodes which have been selected as multipoint relays by some neighbor
   node(s) announce this information periodically in their control
   messages.  Thereby a node announces to the network that it has
   reachability to the nodes which have selected it as an MPR.  Thus, as
   well as being used to facilitate efficient flooding, MPRs are also
   used for route calculation from any given node to any destination in
   the network.

   A node selects MPRs from among its one hop neighbors with
   "symmetric", i.e., bi-directional, linkages.  Therefore, selecting
   the route through MPRs automatically avoids the problems associated
   with data packet transfer over uni-directional links (such as the
   problem of not getting link-layer acknowledgments for data packets at
   each hop, for link-layers employing this technique for unicast
   traffic).

   OLSRv2 is developed to work independently from other protocols.
   Likewise, OLSRv2 makes no assumptions about the underlying link-
   layer.  However, OLSRv2 may use link-layer information and
   notifications when available and applicable.

   OLSRv2, as OLSRv1, inherits the concept of forwarding and relaying



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   from HIPERLAN (a MAC layer protocol) which is standardized by ETSI
   [5].

1.1  Terminology

   The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC2119 [2].

   Additionally, this document uses the following terminology:

   node - a MANET router which implements the Optimized Link State
      Routing protocol as specified in this document.

   OLSRv2 interface - A network device participating in a MANET running
      OLSRv2.  A node may have several OLSRv2 interfaces, each interface
      assigned one or more IP addresses.

   neighbor - A node X is a neighbor of node Y if node Y can hear node X
      (i.e., a link exists from an OLSRv2 interface on node X to an
      OLSRv2 interface on node Y).  A neighbor may also be called a
      1-hop neighbor.

   2-hop neighbor - A node X is a 2-hop neighbor of node Y if node X is
      a neighbor of a neighbor of node Y, but is not node Y itself.

   strict 2-hop neighbor - a 2-hop neighbor which is not a neighbor of
      the node, and is not a 2-hop neighbor only through a neighbor with
      willingness WILL_NEVER.

   multipoint relay (MPR) - A node which is selected by its 1-hop
      neighbor, node X, to "re-transmit" all the broadcast messages that
      it receives from node X, provided that the message is not a
      duplicate, and that the time to live field of the message is
      greater than one.

   multipoint relay selector (MPR selector, MS) - A node which has
      selected its 1-hop neighbor, node X, as one of its multipoint
      relays, will be called an MPR selector of node X.

   link - A link is a pair of OLSRv2 interfaces from two different
      nodes, where at least one interface is able to hear (i.e. receive
      traffic from) the other.

   symmetric link - A link where both interfaces are able to hear (i.e.
      receive messages from) the other.





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   asymmetric link - A link which is not symmetric.

   symmetric 1-hop neighborhood - The symmetric 1-hop neighborhood of
      any node X is the set of nodes which have at least one symmetric
      link to node X.

   symmetric 2-hop neighborhood - The symmetric 2-hop neighborhood of
      node X is the set of nodes, excluding node X itself, which have a
      symmetric link to the symmetric 1-hop neighborhood of X.

   symmetric strict 2-hop neighborhood - The symmetric strict 2-hop
      neighborhood of node X is the set of nodes in its symmetric 2-hop
      neighborhood that are neither in its symmetric 1-hop neighborhood
      nor reachable only through a symmetric 1-hop neighbor of node X
      with willingness WILL_NEVER.


1.2  Applicability Statement

   OLSRv2 is a proactive routing protocol for mobile ad hoc networks
   (MANETs) [6], [7].  It is well suited to large and dense networks of
   mobile nodes, as the optimization achieved using the MPRs works well
   in this context.  The larger and more dense a network, the more
   optimization can be achieved as compared to the classic link state
   algorithm.  OLSRv2 uses hop-by-hop routing, i.e., each node uses its
   local information to route packets.

   As OLSRv2 continuously maintains routes to all destinations in the
   network, the protocol is beneficial for traffic patterns where the
   traffic is random and sporadic between a large subset of nodes, and
   where the [source, destination] pairs are changing over time: no
   additional control traffic need be generated in this situation since
   routes are maintained for all known destinations at all times.  Also,
   since routes are maintained continously, traffic is subject to no
   delays due to buffering/route-discovery.  This continued route
   maintenance may be done using periodic message exchange, as detailed
   in this specification, or triggered by external events if available.

   OLSRv2 supports nodes which have multiple interfaces which
   participate in the MANET.  OLSRv2, additionally, supports nodes which
   have non-MANET interfaces which can serve as (if configured to do so)
   gateways towards other networks.

   The message exchange format, contained in previous versions of this
   specification, has been factored out to an independant specification
   [4], which is used for carrying OLSRv2 control signals.  OLSRv2 is
   thereby able to accommodate for extensions via "external" and
   "internal" extensibility.  External extensibility implies that a



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   protocol extension may specify and exchange new message types which
   can be forwarded and delivered correctly according to [4].  Internal
   extensibility implies, that a protocol extension may define
   additional attributes to be carried embedded in the OLSRv2 control
   messages, detailed in this specification, while these OLSRv2 control
   messages with additional attributes can still be correctly understood
   by all OLSRv2 nodes.












































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2.  Protocol Overview and Functioning

   OLSRv2 is a proactive routing protocol for mobile ad hoc networks.
   The protocol inherits the stability of a link state algorithm and has
   the advantage of having routes immediately available when needed due
   to its proactive nature.  OLSRv2 is an optimization over the
   classical link state protocol, tailored for mobile ad hoc networks.
   The main tailoring and optimizations of OLSRv2 are:

   o  periodic, unacknowledged transmission of all control messages;

   o  optimized flooding for global link-state information diffusion;

   o  partial topology maintenance -- each node will know of all
      destinations and a subset of links in the network.

   More specifically, OLSRv2 consists of the following main components:

   o  A general and flexible signaling framework, allowing for
      information exchange between OLSRv2 nodes.  This framework allows
      for both local information exchange (between neighboring nodes)
      and global information exchange using an optimized flooding
      mechanism denoted "MPR flooding".

   o  A specification of local signaling, denoted HELLO messages.  HELLO
      messages in OLSRv2 serve to:

      *  discover links to adjacent OLSR nodes;

      *  perform bidirectionality check on the discovered links;

      *  advertise neighbors and hence discover 2-hop neighbors;

      *  signal MPR selection.

      HELLO messages are emitted periodically, thereby allowing nodes to
      continuously track changes in their local neighborhoods.

   o  A specification of global signaling, denoted TC messages.  TC
      messages in OLSRv2 serve to:

      *  inject link-state information into the entire network.

      *  inject addresses of hosts and networks for which they may serve
         as a gateway into the entire network.

      *  allow nodes with multiple interface addresses to ensure that
         nodes within two hops can associate these addresses with a



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         single node for efficient MPR Set determination.

      TC messages are emitted periodically, thereby allowing nodes to
      continuously track global changes in the network.

   Thus, through periodic exchange of HELLO messages, a node is able to
   acquire and maintain information about its immediate neighborhood.
   This includes information about immediate neighbors, as well as nodes
   which are two hops away.  By HELLO messages being exchanged
   periodically, a node learns about changes in the neighborhood (new
   nodes emerging, old nodes disappearing) without requiring explicit
   mechanisms for doing so.

   Based on the local topology information, acquired through the
   periodic exchange of HELLO messages, an OLSRv2 node is able to make
   provisions for ensuring optimized flooding, denoted "MPR flooding",
   as well as injection of link-state information into the network.
   This is done through the notion of Multipoint Relays.

   The idea of multipoint relays is to minimize the overhead of flooding
   messages in the network by reducing redundant retransmissions in the
   same region.  Each node in the network selects a set of nodes in its
   symmetric 1-hop neighborhood which may retransmit its messages.  This
   set of selected neighbor nodes is called the "Multipoint Relay" (MPR)
   Set of that node.  The neighbors of node N which are *NOT* in its MPR
   set, receive and process broadcast messages but do not retransmit
   broadcast messages received from node N. The MPR Set of a node is
   selected such that it covers (in terms of radio range) all symmetric
   strict 2-hop nodes.  The MPR Set of N, denoted as MPR(N), is then an
   arbitrary subset of the symmetric 1-hop neighborhood of N which
   satisfies the following condition: every node in the symmetric strict
   2-hop neighborhood of N MUST have a symmetric link towards MPR(N).
   The smaller a MPR Set, the less control traffic overhead results from
   the routing protocol. [7] gives an analysis and example of MPR
   selection algorithms.  Notice, that as long as the condition above is
   satisfied, any algorithm selecting MPR Sets is acceptable in terms of
   implementation interoperability.

   Each node maintains information about the set of neighbors that have
   selected it as MPR.  This set is called the "Multipoint Relay
   Selector Set" (MPR Selector Set) of a node.  A node obtains this
   information from periodic HELLO messages received from the neighbors.
   Each node also maintains a Relay Set, which is the set of nodes for
   which a node is to relay broadcast traffic.  The Relay Set is derived
   from the MPR Selector Set in that the Relay Set MUST contain all the
   nodes in the MPR Selector set and MAY contain additional nodes.

   A broadcast message, intended to be diffused in the whole network,



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   coming from any of the nodes in the Relay Set of node N is assumed to
   be retransmitted by node N, if N has not received it yet.  This set
   can change over time (e.g., when a node selects another MPR Set) and
   is indicated by the selector nodes in their HELLO messages.

   Using the MPR flooding mechanism, link-state information can be
   injected into the network.  For this purpose, a node maintains an
   Advertised Neighbor Set which MUST contain all the nodes in the MPR
   selector set and MAY contain additional nodes.  If the Advertised
   Neighbor Set of a node is non-empty, TC messages, containing the
   links between the node and the nodes in the Advertised Neighbor Set,
   are not generated, unless needed for gateway reporting or multiple
   interface address association (if the latter case only, with minimal
   scope).

   OLSRv2 is designed to work in a completely distributed manner and
   does not depend on any central entity.  The protocol does not require
   reliable transmission of control messages: each node sends control
   messages periodically, and can therefore sustain a reasonable loss of
   some such messages.  Such losses occur frequently in radio networks
   due to collisions or other transmission problems.

   Also, OLSRv2 does not require sequenced delivery of messages.  Each
   control message contains a sequence number which is incremented for
   each message.  Thus the recipient of a control message can, if
   required, easily identify which information is more recent - even if
   messages have been re-ordered while in transmission.  Furthermore,
   OLSRv2 provides support for protocol extensions such as sleep mode
   operation, multicast-routing etc.  Such extensions may be introduced
   as additions to the protocol without breaking backwards compatibility
   with earlier versions.

   OLSRv2 does not require any changes to the format of IP packets.
   Thus any existing IP stack can be used as is: OLSRv2 only interacts
   with routing table management.  OLSR sends its own control messages
   using UDP.

2.1  Protocol Extensibility

   This specification defines and uses two OLSRv2 message types, HELLO
   and TC.  As for OLSRv1 [1] extensions to OLSRv2 may define new
   message types to carry additional information.  This may be
   considered as "external" extensibility.  New message types are
   divided into two ranges, those which may be added by standards
   actions (with types up to 127) and those made available for private/
   local use (with types 128 to 255).

   All new messages must be syntactically OLSRv2 messages, as defined in



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   [4].  (Some additional constraints to that specification are added
   for OLSRv2 packets and messages, requiring full packet and message
   headers.)  Note that if it is required to include one or more blocks
   of unstructured data in such a message (possibly as its only content)
   this may be achieved by including each block as a single message TLV
   block, with an appropriately defined message TLV.  (Like message
   types, TLV types are divided into those up to 127 which may be added
   by standards action, and those from 128 to 255 available for private/
   local use.)

   A network may contain nodes both aware of, and unaware of, any new
   message types.  The originator of a message can control whether a
   message flooded through the network is forwarded by nodes which are
   unaware of the message type, thus reaching all nodes in the network,
   or is only flooded by nodes which recognise the message type.

   OLSRv2 also supports an alternative, and more powerful, extension
   mechanism which was not supported by OLSRv1, that of adding new
   information to an already defined message type, whilst still leaving
   the predefined information unchanged and usable, including by a node
   which does not recognise the new information.  This may be considered
   to be "internal" extensibility of a message.

   The mechanism for this extensibility is the use of TLV (type-length-
   value) structures in the message format defined in [4] to carry
   information associated with either the message as a whole, or with
   one or more addresses carried in the message.  The messages defined
   in this specification carry two types of addresses, those of the
   originating node's own interfaces participating in OLSRv2, and those
   of neighbouring nodes or networks to which it has a route.  (New
   message types may define other relationships to addresses which they
   carry.)  All information associated with these addresses, or the
   message as a whole, in messages defined in this specification is in
   TLV format; additional TLVs may be defined and added to these
   messages.

   Those nodes which do not recognise newly defined TLV types ignore the
   added TLVs.  (This is facilitated by that the TLVs defined in this
   specification, or in [4], have the lowest type numbers and that TLVs
   must be included in type order, as specified in [4].)  It is
   important that newly defined TLV types permit this behaviour.










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3.  Processing and Forwarding Repositories

   The following data-structures are employed in order to ensure that a
   message is processed at most once and is forwarded at most once per
   interface of a node, and that fragmented content is treated
   correctly.

3.1  Received Message Set

   Each node maintains, for each OLSRv2 interface it possesses, a set of
   signatures of messages, which have been received over that interface,
   in the form of "Received Tuples":

      (RX_type, RX_addr, RX_seq_number, RX_time)

   where:

   RX_type is the received message type, or zero if the received message
      sequence number is not type-specific.

   RX_addr is the originator address of the received message;

   RX_seq_number is the message sequence number of the received message;

   RX_time specifies the time at which this record expires and *MUST* be
      removed.

   In a node, this is denoted the "Received Message Set" for that
   interface.

3.2   Fragment Set

   Each node stores messages containing fragmented content until all
   fragments are received and the message processing can be completed,
   in the form of "Fragment Tuples":

      (FG_message, FG_time)

   where:

   FG_message is the message containing fragmented content;

   FG_time specifies the time at which this record expires and MUST be
      removed.

   In a node, this is denoted the "Fragment Set".





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3.3  Processed Set

   Each node maintains a set of signatures of messages which have been
   processed by the node, in the form of "Processed Tuples":

      (P_type, P_addr, P_seq_number, P_time)

   where:

   P_type is the processed message type, or zero if the processed
      message sequence number is not type-specific.

   P_addr is the originator address of the processed message;

   P_seq_number is the message sequence number of the processed message;

   P_time specifies the time at which this record expires and *MUST* be
      removed.

   In a node, this is denoted the "Processed Set".

3.4  Forwarded Set

   Each node maintains a set of signatures of messages which have been
   retransmitted/forwarded by the node, in the form of "Forwarded
   Tuples":

      (FW_type, FW_addr, FW_seq_number, FW_time)

   where:

   FW_type is the forwarded message type, or zero if the forwarded
      message sequence number is not type-specific.

   FW_addr is the originator address of the forwarded message;

   FW_seq_number is the message sequence number of the forwarded
      message;

   FW_time specifies the time at which this record expires and *MUST* be
      removed.

   In a node, this is denoted the "Forwarded Set".

3.5  Relay Set

   Each node maintains a set of neighbor interface addresses for which
   it is to relay flooded messages, in the form of "Relay Tuples":



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      (RY_if_addr)

   where:

   RY_if_addr is the address of a neighbor interface for which the node
      SHOULD relay flooded messages.

   In a node, this is denoted the "Relay Set".











































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4.  Packet Processing and Message Forwarding

   Upon receiving a basic packet, a node examines each of the message
   headers.  If the message type is known to the node, the message is
   processed locally according to the specifications for that message
   type.  The message is also independently evaluated for forwarding.

4.1  Actions when Receiving an OLSRv2 Packet

   Upon receiving a packet, a node MUST perform the following task:

   1.  If the packet contains no messages (i.e. the packet length is
       less than or equal to the size of the packet header) or if the
       packet cannot be parsed into messages, the packet MUST be
       silently discarded.

   2.  Otherwise, each message in the packet is treated according to
       Section 4.2.


4.2  Actions when Receiving an OLSRv2 Message

   A node MUST perform the following tasks for each received OLSRv2
   message:

   1.  If the received OLSRv2 message header cannot be correctly parsed
       according to the specification in [4], or if the originator
       address of the message is an interface address of the receiving
       node then the message MUST be silently discarded;

   2.  Otherwise:

       1.  If the message is of a known type then the message is
           considered for processing according to Section 4.3;

       2.  If for the received message TTL > 0, and if either the
           message is of a known type, or bit 3 of the message semantics
           octet in the message header is clear, as indicated in [4],
           then the message is considered for forwarding according to
           Section 4.4.


4.3  Message Considered for Processing

   If a message is considered for processing, the following tasks MUST
   be performed:





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   1.  If an entry exists in the Processed Set where:

       *  P_type == the message type, or 0 if bit 2 of the message
          semantics octet (in the message header) is clear, AND;

       *  P_addr == the originator address of the message, AND;

       *  P_seq_number == the sequence number of the message.

       then the message MUST NOT be processed.

   2.  Otherwise:

       1.  Create an entry in the Processed Set with:

           +  P_type = the message type, or 0 if bit 2 of the message
              semantics octet (in the message header) is clear;

           +  P_addr = originator address of the message;

           +  P_seq_number = sequence number of the message;

           +  P_time = current time + P_HOLD_TIME.

       2.  If the message does not contain a message TLV of type
           Fragment (or if it does and the indicated number of fragments
           is one) then process the message fully according to its type.

       3.  Otherwise:

           1.  If the message is "wholly or partially self-contained" as
               indicated by its Fragment TLV then process the current
               message as far as possible according to its type;

           2.  If the Fragment Set includes any messages with the same
               originator address and content sequence number as the
               current message, and either the same fragment number or a
               different number of fragments, then remove these messages
               are from the Fragment Set;

           3.  If the Fragment Set includes messages containing all the
               remaining fragments of the same overall message as the
               current message (i.e. if the number of messages in the
               Fragment Set with the same originator address and content
               sequence number as the current message is equal to the
               current message's number of fragments, less one) then all
               of these messages are removed from the Fragment Set and
               processed according to their type (taking account of any



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               previous processing if any or all were wholly or
               partially self-contained);

           4.  Otherwise, the current message is added to the Fragment
               Set with a FG_time of FG_HOLD_TIME (possibly replacing an
               identical and previous received instance of the same
               fragment of the same content).


4.4  Message Considered for Forwarding

   If a message is considered for forwarding then if it is either of a
   message type defined in this document, or of an unknown message type
   it MUST use the following algorithm.  A message type not defined in
   this document may specify the use of this, or another algorithm.
   (Such an other algorithm MAY use the Received Set for the receiving
   interface, it SHOULD use the Forwarded Set similarly to the following
   algorithm.)

   If a message is considered for forwarding according to this
   algorithm, the following tasks MUST be performed:

   1.  If there is no symmetric link in the Link Set between the
       receiving interface and the sending interface (as indicated by
       the source interface of the IP datagram containing the message)
       then the message MUST be silently discarded.

   2.  Otherwise:

       1.  If an entry exists in the Received Set for the receiving
           interface, where:

           +  RX_type == the message type, or 0 if bit 2 of the message
              semantics octet (in the message header) is clear, AND;

           +  RX_addr == the originator address of the received message,
              AND;

           +  RX_seq_number == the sequence number of the received
              message.

           then the message MUST be silently discarded.

       2.  Otherwise:

           1.  Create an entry in the Received Set for the receiving
               interface with:




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               -  RX_type = the message type, or 0 if bit 2 of the
                  message semantics octet (in the message header) is
                  clear;

               -  RX_addr = originator address of the message;

               -  RX_seq_number = sequence number of the message;

               -  RX_time = current time + RX_HOLD_TIME.

           2.  If an entry exists in the Forwarded Set where:

               -  FW_type == the message type, or 0 if bit 2 of the
                  message semantics octet (in the message header) is
                  clear;

               -  FW_addr == the originator address of the received
                  message, AND;

               -  FW_seq_number == the sequence number of the received
                  message.

               then the message MUST be silently discarded.

           3.  Otherwise if an entry exists in the Relay Set, where
               RY_if_addr == source address of the message (as indicated
               by the source interface of the IP datagram containing the
               message):

               1.  Create an entry in the Forwarded Set with:

                   o  FW_type = the message type, or 0 if bit 2 of the
                      message semantics octet (in the message header) is
                      clear;

                   o  FW_addr = originator address of the message;

                   o  FW_seq_number = sequence number of the message;

                   o  FW_time = current time + FW_HOLD_TIME.

               2.  The message header is modified as follows:

                   o  Decrement the message TTL by 1;

                   o  Increment the message hop count by 1;





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               3.  Transmit the message on all OLSRv2 interfaces of the
                   node.

   Messages are retransmitted in the format specified by [4] with the
   All-OLSRv2-Multicast address (see Section 17.1) as destination IP
   address.













































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5.  Information Repositories

   The purpose of OLSRv2 is to determine the Routing Set, which may be
   used to update IP's Routing Table, providing "next hop" routing
   information for IP datagrams.  In order to accomplish this, OLSRv2
   maintains a number of protocol sets, the information repository of
   the protocol.  These sets are updated, directly or indirectly, by the
   exchange of messages between nodes in the network.  In turn the
   contents of these messages are largely determined by the contents of
   a part of the information repositories, the Neighbourhood Information
   Base, which contains information about the 1- and 2- hop
   neighbourhoods of the node.  The remaining part of the information
   repository, the Topology Information Base (including the Routing Set)
   contains information about the network which is not constrained to
   the node's neighbourhood.  The Topology Information Base is updated
   by the OLSRv2 messages defined in this document, it is not used to
   define their contents.  The process of information exchange which
   leads to the population of the Neighbourhood Information Base and the
   Topology Information Base is started using only the node's own OLSRv2
   interface addresses and host and network associated addresses.  These
   are not affected by the exchange of the OLSRv2 messages defined in
   this document.

5.1  Neighborhood Information Base

   The neighborhood information base stores information about links
   between local interfaces and interfaces on adjacent nodes.

5.1.1  Link Set

   A node records a set of "Link Tuples":

     (L_local_iface_addr, L_neighbor_iface_addr,
      L_SYM_time, L_ASYM_time, L_willingness, L_time).

   where:

   L_local_iface_addr is the interface address of the local node;

   L_neighbor_iface_addr is the interface address of the neighbor node;

   L_SYM_time is the time until which the link is considered symmetric;

   L_ASYM_time is the time until which the neighbor interface is
      considered heard;






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   L_willingness is the nodes willingness to be selected as MPR;

   L_time specifies when this record expires and *MUST* be removed.

              +-------------+-------------+--------------+
              | L_SYM_time  | L_ASYM_time | L_STATUS     |
              +-------------+-------------+--------------+
              | Expired     | Expired     | LOST         |
              |             |             |              |
              | Not Expired | Expired     | SYMMETRIC    |
              |             |             |              |
              | Not Expired | Not Expired | SYMMETRIC    |
              |             |             |              |
              | Expired     | Not Expired | ASYMMETRIC   |
              +-------------+-------------+--------------+

                                  Table 1

   The status of the link, denoted L_STATUS, can be derived based on the
   fields L_SYM_time and L_ASYM_time as defined in Table 1.

   In a node, the set of Link Tuples is denoted the "Link Set".

5.1.2  2-Hop Neighbor Set

   A node records a set of "2-Hop Neighbor Tuples"

    (N2_local_iface_addr, N2_neighbor_iface_addr, N2_2hop_iface_addr, N2_time)

   describing symmetric links between its neighbors and the symmetric
   2-hop neighborhood.

   N2_local_iface_addr is the address of the local interface over which
      the information was received;

   N2_neighbor_iface_addr is the interface address of a neighbor;

   N2_2hop_iface_addr is the interface address of a 2-hop neighbor with
      a symmetric link to the node with interface address
      N_neighbor_iface_addr;

   N2_time specifies the time at which the tuple expires and *MUST* be
      removed.

   In a node, the set of 2-Hop Neighbor Tuples is denoted the "2-Hop
   Neighbor Set".





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5.1.3  Neighborhood Address Association Set

   A node maintains, for each 1-hop and 2-hop neighbor with multiple
   addresses participating in the OLSRv2 network, a "Neighborhood
   Address Association Tuple", representing that "these addresses belong
   to the same node".

       (NA_neighbor_addr_list, NA_time)

   NA_neighbor_iface_addr_list is the list of interface addresses of the
      1-hop or 2-hop neighbor node;

   NA_time specifies the time at which the tuple expires and *MUST* be
      removed.

   In a node, the set of Neighborhood Address Association Tuples is
   denoted the "Neighborhood Address Association Set".

5.1.4  MPR Set

   A node maintains a set of neighbors which are selected as MPRs.
   Their interface addresses are listed in the MPR Set.

5.1.5  MPR Selector Set

   A node maintains, for each interface of an 1-hop neighbor which has
   selected it as MPR, an "MPR Selector Tuple", representing the an
   interface of the neighbor node which have selected it as an MPR.

       (MS_neighbor_if_addr, MS_time)

   MS_neighbor_if_addr specifies the interface address of a 1-hop
      neighbor, which has selected the node as MPR;

   MS_time specifies the time at which the tuple expires and *MUST* be
      removed.

   Notice that if a MPR selector node has multiple interface addresses,
   the MPR Selector Set will contain one tuple for each interface
   address of the MPR selector.

5.1.6  Advertised Neighbor Set

   A node maintains a set of neighbor interface addresses, which are to
   be advertised through TC messages:

           (A_neighbor_iface_addr)




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   For this set, an Advertised Neighbor Set Sequence Number (ASSN) is
   maintained.  Each time the Advertised Neighbor Set is updated, the
   ASSN MUST be incremented.

5.2  Topology Information Base

   The Topology Information Base stores topological information
   describing the network beyond the nodes neighborhood (i.e. beyond the
   Neighborhood Information Base of the node).

5.2.1  Topology Set

   Each node in the network maintains topology information about the
   network.

   For each destination in the network, at least one "Topology Tuple"

       (T_dest_iface_addr, T_last_iface_addr, T_seq, T_time)

   is recorded.

   T_dest_iface_addr is the interface address of a node, which may be
      reached in one hop from the node with the interface address
      T_last_iface_addr;

   T_last_iface_addr is, conversely, the last hop towards
      T_dest_iface_addr.  Typically, T_last_iface_addr is a MPR of
      T_dest_iface_addr;

   T_seq is a sequence number, and

   T_time specifies the time at which this tuple expires and *MUST* be
      removed.

   In a node, the set of Topology Tuples are denoted the "Topology Set".

5.2.2  Attached Network Set

   Each node in the network maintains information about attached
   networks.

   For each attached network, at least one "Attached Network Tuple"

       (AN_net_addr, AN_prefix_lenght, AN_gw_addr, AN_seq_no, AN_time)

   is recorded.





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   AN_net_addr is the network address (prefix) of a network, which may
      be reached via the node with the OLSRv2 interface address
      AN_gw_addr;

   AN_prefix_length is the length of the prefix of the network address
      AN_net_addr;

   AN_gw_addr is the address of an OLSRv2 interface of a node which can
      act as gateway to the network identified by the AD_net_addr/
      AD_prefix_length;

   AN_seq_no is a sequence number, and;

   AN_time specifies the time at which this tuple expires and *MUST* be
      removed.

   In a node, the set of Topology Tuples are denoted the "Topology Set".

5.2.3  Routing Set

   A node records a set of "Routing Tuples":

      (R_dest_iface_addr, R_next_iface_addr, R_dist, R_iface_addr)

   describing the next hop and distance of the path to each destination
   in the network for which a route is known.

   R_dest_iface_addr is the interface address of the destination node;

   R_next_iface_addr is the interface address of the "next hop" on the
      path towards R_dest_iface_addr;

   R_dist is the number of hops on the path to R_dest_iface_addr;

   R_iface_addr is the address of the local interface over which a
      packet MUST be sent to reach R_next_iface_addr.

   In a node, the set of Routing Tuples is denoted the "Routing Set".













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6.  OLSRv2 Control Message Structures

   Nodes using OLSRv2 exchange information through messages.  One or
   more messages sent by a node at the same time are combined into a
   packet.  These messages may have originated at the sending node, or
   have originated at another node and forwarded by the sending node.
   Messages with different originators may be combined in the same
   packet.

   The packet and message format used by OLSRv2 is defined in [4].
   However this specification contains some options which are not used
   by OLSRv2.  In particular (using the syntactical elements defined in
   the packet format specification):

   o  All OLSRv2 packets include a <packet-header>.

   o  All OLSRv2 messages, not limited to those defined in this
      document, include a full <msg-header> and hence have bits 0 and 1
      of <msg-semantics> cleared.

   o  All OLSRv2 message defined in this document have all remaining
      bits of <msg-semantics> cleared.

   Other options defined in [4] may be freely used, in particular any
   values of <tlv-semantics> consistent with its specification.  An
   implementation of OLSRv2 MAY take full advantage of the features of
   the message specification in [4] allowing decisions relating to
   whether a message should be forwarded and/or processed to be taken
   parsing only the message header (plus, if a message is to be
   processed but may be fragmented, only the first octets of the message
   body).

   OLSRv2 messages are sent using UDP, see Appendix C.

   The remainder of this section defines, within the framework of [4],
   message types and TLVs specific to OLSRv2.

6.1  General OLSRv2 Message TLVs

   This document specifies two message TLVs, which can be applied to any
   OLSRv2 control message, VALIDITY_TIME and INTERVAL_TIME, detailed in
   this section.

6.1.1  VALIDITY_TIME TLV

   All OLSRv2 messages specified in this specification MUST include a
   VALIDITY_TIME TLV, specifying for how long a node may, upon receiving
   a message, consider the message content to be valid.  The validity



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   time of a message MAY be specified to depend on the distance from the
   originator (i.e. the <hop-count> field in the message header as
   defined in [4]).  Thus, the VALIDITY_TIME TLV contains a sequence of
   pairs (time, hop-limit) in increasing hop-limit order, followed by a
   default value.

   Thus, an instance of a VALIDITY_TIME TLV could have the following
   value:

     <t_1><hl_1><t_2><hl_2> ... <t_i><hl_i> ....  <t_n><hl_n><t_default>

   Which would mean that the message, carrying this VALIDITY_TIME TLV,
   would have the following validity times:

   o  <t_1> in the interval from 0 (exclusive) to <hl_1> (inclusive)
      hops away from the originator;

   o  <t_i> in the interval from <hl_(i-1)> (exclusive) to <hl_i>
      (inclusive) hops away from the originator; and

   o  <t_default> in the interval from <hl_n> (exclusive) to 255>
      (inclusive) hops away from the originator.

   The VALIDITY_TIME message TLV specification is given in Table 2.

   VALIDITY_TIME message TLV specification overview

   +----------------+--------+-------------------+---------------------+
   |      Name      |  Type  |       Length      | Value               |
   +----------------+--------+-------------------+---------------------+
   |  VALIDITY_TIME |   TBD  |  (2*n+1) * 8 bits | {<time><hoplimit>}* |
   |                |        |                   | <t_default>         |
   +----------------+--------+-------------------+---------------------+

                                  Table 2

   where <n> is the number of (time, hop_limit) pairs in the TLV, and
   where <time> and <t_default> are represented as specified in section
   Section 16.

6.1.2  INTERVAL_TIME TLV

   OLSRv2 messages of a given type MAY include an INTERVAL_TIME message
   TLV, specifying the interval at which messages of this type are being
   generated by the originator node.

   The INTERVAL_TIME message TLV specification is given in Table 3.




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   INTERVAL_TIME TLV specification overview

   +----------------+--------+-------------------+---------------------+
   |      Name      |  Type  |       Length      | Value               |
   +----------------+--------+-------------------+---------------------+
   |  INTERVAL_TIME |   TBD  |       8 bits      | <time>              |
   +----------------+--------+-------------------+---------------------+

                                  Table 3

   where <time> is the time between two successive emissions of messages
   of the type, represented as specified in section Section 16.

6.2  Local Interface Blocks

   The first address block, plus following TLV block in a HELLO or TC
   message is known as a Local Interface Block.  A Local Interface Block
   is not distinguished in any way other than by being the first address
   block in the message.

   A Local Interface Block contains the addresses of all of the
   interfaces of the originating node that support OLSRv2 and
   participate in the MANET, using the standard <address-block> syntax
   from [4].  In a TC message this is sufficient; in a HELLO message,
   those addresses, if any, which correspond to interfaces other than
   that on which the HELLO message is sent must have a corresponding
   OTHER_IF TLV.  In this case (only) this OTHER_IF TLV SHALL NOT have a
   <value> field.

   Note that a Local Interface Block may include more than one address
   for each interface, and hence in a HELLO message may contain more
   than one address without an OTHER_IF TLV.

6.3  HELLO Messages

   A HELLO message MUST contain:

   o  a message TLV VALIDITY_TIME Section 6.1.1

   o  one or more address blocks with associated address block TLVs

   The first (mandatory) address block is a Local Interface Block, as
   specified in Section 6.2.  Other (optional) address blocks contain
   1-hop neighbors' interface addresses.

   A HELLO message MAY optionally contain:





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   o  a message TLV INTERVAL_TIME as specified in Section 6.1.2

   o  a message TLV WILLINGNESS, as specified in Section 6.3.1


6.3.1  HELLO Message: Message TLVs

   In a HELLO message, a node MAY include a message TLV as specified in
   Table 4.

   VALIDITY_TIME message TLV specification overview

   +----------------+--------+-------------------+---------------------+
   |      Name      |  Type  |       Length      | Value               |
   +----------------+--------+-------------------+---------------------+
   |   WILLINGNESS  |   TBD  |       8 bits      | <The node's         |
   |                |        |                   | willingness to be   |
   |                |        |                   | selected as MPR>    |
   +----------------+--------+-------------------+---------------------+

                                  Table 4

   A node's willingness to be selected as MPR ranges from WILL_NEVER
   (indicating that a node MUST NOT be selected as MPR by any node) to
   WILL_ALWAYS (indicating that a node MUST always be selected as MPR.

   If a node does not advertise a Willingness TLV in HELLO messages, the
   node MUST be assumed to have a willingness of WILL_DEFAULT.

6.3.2  HELLO Message: Address Blocks TLVs

   HELLO message address block TLV specification overview

   +----------------+--------+-------------------+---------------------+
   |      Name      |  Type  |       Length      | Value               |
   +----------------+--------+-------------------+---------------------+
   |   LINK_STATUS  |   TBD  |       8 bits      | One of HEARD,       |
   |                |        |                   | SYMMETRIC, LOST.    |
   |                |        |                   |                     |
   |       MPR      |   TBD  |       0 bits      | No value, i.e.      |
   |                |        |                   | novalue bit (see    |
   |                |        |                   | [4]) set            |
   |                |        |                   |                     |








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   |    OTHER_IF    |   TBD  |    0 or 8 bits    | In a Local          |
   |                |        |                   | Interface Block     |
   |                |        |                   | none, otherwise     |
   |                |        |                   | either of SYMMETRIC |
   |                |        |                   | or LOST             |
   +----------------+--------+-------------------+---------------------+

                                  Table 5


6.4  TC Messages

   A TC message MUST contain:

   o  a message TLV VALIDITY_TIME Section 6.1.1

   o  a message TLV CONTENT_SEQUENCE_NUMBER [4]

   o  one or more address blocks with associated address block TLVs.

   The first (mandatory) address block is a Local Interface Block, as
   specified in Section 6.2.  Other (optional) address blocks contain
   1-hop neighbors' interface addresses and/or host or network addresses
   for which this node may act as a gateway.  In the latter case they
   may use PREFIX_LENGTH TLV(s) as specified in [4].

   A TC message MAY optionally contain:

   o  a message TLV INTERVAL_TIME as specified in Section 6.1.2






















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7.  HELLO Message Generation

   An OLSRv2 HELLO message is composed of a set of message TLVs,
   describing general properties of the message and the node emitting
   the HELLO, and a set of address blocks (with associated TLV sets),
   describing the links and their associated properties.

   OLSRv2 HELLO messages are generated and transmitted per interface,
   i.e. different HELLO messages are generated and transmitted per
   OLSRv2 interface of a node.

   OLSRv2 HELLO messages are generated and transmitted periodically,
   with a default interval between two consecutive HELLO emissions on
   the same interface of HELLO_INTERVAL.

   This section specifies the requirements, which HELLO message
   generation MUST fulfill.  An example algorithm is proposed in
   Appendix B.1.

   For each OLSRv2 interface a node MUST generate a HELLO message with a
   Local Interface Block as the first address block, as specified in
   Section 6.2, followed by address blocks and address TLVs according to
   Table 6.

   +---------------------------+---------------------------------------+
   | The set of neighbor       | TLV(s) (Type = Value)                 |
   | interfaces which are ...  |                                       |
   +---------------------------+---------------------------------------+
   | HEARD, but not SYMMETRIC  | LINK_STATUS=HEARD                     |
   | over the interface over   |                                       |
   | which the HELLO message   |                                       |
   | is being transmitted      |                                       |
   |                           |                                       |
   | SYMMETRIC over the        | LINK_STATUS=SYMMETRIC                 |
   | interface over which the  |                                       |
   | HELLO message is being    |                                       |
   | transmitted               |                                       |
   |                           |                                       |
   | LOST over the interface   | LINK_STATUS=LOST                      |
   | over which the HELLO      |                                       |
   | message is being          |                                       |
   | transmitted               |                                       |
   |                           |                                       |








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   | Not SYMMETRIC over the    | OTHER_IF=SYMMETRIC                    |
   | interface over which the  |                                       |
   | HELLO message is being    |                                       |
   | transmitted, but          |                                       |
   | SYMMETRIC over one or     |                                       |
   | more other interfaces of  |                                       |
   | the node                  |                                       |
   |                           |                                       |
   | Not SYMMETRIC over any    | OTHER_IF=LOST                         |
   | interface or LOST over    |                                       |
   | the interface over which  |                                       |
   | the HELLO message is      |                                       |
   | being transmitted, but    |                                       |
   | previously reported as    |                                       |
   | OTHER_IF=SYMMETRIC and    |                                       |
   | still HEARD or LOST over  |                                       |
   | one or more interfaces of |                                       |
   | the node other than the   |                                       |
   | interface over which the  |                                       |
   | HELLO message is being    |                                       |
   | transmitted               |                                       |
   |                           |                                       |
   | Selected as MPR for the   | MPR                                   |
   | interface over which the  |                                       |
   | HELLO message is          |                                       |
   | transmitted               |                                       |
   +---------------------------+---------------------------------------+

                                  Table 6

   In order that an address can be reported as OTHER_IF=LOST by a node
   with more than one interface participating in the MANET, such a node
   MAY maintain an Other Interface Set of addresses for each interface.
   The Other Interface Set for an interface is updated when a HELLO
   message is to be transmitted over that interface, and used to
   determine which addresses are reported as OTHER_IF=LOST in that
   message.  The Other Interface Set of addresses is updated and used as
   follows:

   1.  Each address that the HELLO message is to include with a
       corresponding TLV with Type=LINK_STATUS and Value=SYMMETRIC is
       removed from the set.

   2.  Each address that the HELLO message is to include with a
       corresponding TLV with Type=OTHER_IF and Value=SYMMETRIC is added
       to the set if not already present.





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   3.  Each other address in the set (not included in the HELLO message
       with a corresponding TLV with Type=OTHER_IF and Value=SYMMETRIC)

       1.  Is removed if the HELLO message is to include it with a
           corresponding TLV with Type=LINK_STATUS and Value=LOST.

       2.  Is removed if it is not HEARD or LOST over an interface other
           than the interface over which the HELLO message is to be
           transmitted.

       3.  Otherwise is included in the HELLO message with a TLV with
           Type=OTHER_IF and Value=LOST.  (Note that the address may
           also have a corresponding TLV with Type=LINK_STATUS and
           Value=HEARD if appropriate.)


7.1  HELLO Message: Transmission

   Messages are retransmitted in the packet/message format specified by
   [4] with the All-OLSRv2-Multicast address as destination IP address
   and with a TTL=1.






























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8.  HELLO Message Processing

   Upon receiving a HELLO message, a node will update its local link
   information base according to the specification given in this
   section.

   For the purpose of this section, please notice the following:

   o  the "validity time" of a message is calculated from the VALIDITY-
      TIME TLV of the message as specified in Section 6.1.1;

   o  the "Source Address" is the source address as indicated by the
      source interface of the IP datagram containing the message;

   o  a HELLO message MUST neither be forwarded nor be recorded in the
      Processing and Forwarding Repositories;

   o  the address blocks considered exclude the Local Interface Block,
      unless explicitly specified;

   o  a HELLO message is only valid when, for each address listed in the
      address blocks:

      *  the address is associated with a TLV with Type=Link Status OR a
         TLV with Type=Other Interface Status OR both, the latter either
         when the TLV with Type=Link Status has Value=HEARD, or when the
         the TLV with Type=Link Status has Value=LOST and the TLV with
         Type=Other Interface Status has Value=SYMMETRIC, AND

      *  if the address is associated with a TLV with Type=MPR, then it
         MUST also be associated with a TLV with Type=Link Status and
         Value=SYMMETRIC.

      Invalid HELLO messages are not processed.


8.1  Populating the Link Set

   Upon receiving a HELLO message, a node SHOULD update its Link Set
   with the information contained in the HELLO.  Thus, for the Local
   Interface Block (see Section 6.2) the Neighbor Address Association
   Set is updated as specified by Section 13.  For each address, listed
   in the subsequent HELLO message address blocks (see Section 6):

   1.  if there exists no link tuple with:

       *  L_neighbor_iface_addr == Source Address




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       a new tuple is created with

       *  L_neighbor_iface_addr = Source Address;

       *  L_local_iface_addr    = Address of the interface which
          received the HELLO message;

       *  L_SYM_time            = current time - 1 (expired);

       *  L_time                = current time + validity time.

   2.  The tuple (existing or new) with L_neighbor_iface_addr == Source
       Address is then modified as follows:

       1.  if the node finds the address of the interface, which
           received the HELLO message, in one of the address blocks
           included in message, then the tuple is modified as follows:

           1.  if the occurrence of L_local_iface_addr in the HELLO
               message is:

               -  associated with a TLV with (Type == "LINK_STATUS",
                  Value == LOST)

               then

               -  L_SYM_time = current time - 1 (i.e., expired)

           2.  else if the occurrence of L_local_iface_addr in the HELLO
               message:

               -  is associated with:

                  o  a TLV with (Type == "LINK_STATUS", Value ==
                     SYMMETRIC);

                  OR;

                  o  a TLV with (Type == "LINK_STATUS", Value == HEARD);

               then

               -  L_SYM_time = current time + validity time,

               -  L_time     = L_SYM_time + L_HOLD_TIME.






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       2.  L_ASYM_time = current time + validity time;

       3.  L_time = max(L_time, L_ASYM_time)

   3.  Additionally, the willingness field is updated as follows:

          If a TLV with Type=="WILLINGNESS" is present in the message
          TLVs, then:

          +  L_willingness = Value of the TLV

          otherwise:

          +  L_willingness = WILL_DEFAULT

   The rule for setting L_time is the following: a link losing its
   symmetry SHOULD still be advertised in HELLOs (with the remaining
   status as defined by Table 1) during at least the duration of the
   "validity time".  This  allows neighbors to detect the link breakage.
   Thus, the Local Link Set must maintain information, also about LOST
   links, until the link would otherwise expire.

8.2  Populating the 2-Hop Neighbor Set

   Upon receiving a HELLO message from a symmetric neighbor interface, a
   node SHOULD update its 2-hop Neighbor Set.

   If the Source Address is the L_local_iface_addr from a link tuple
   included in the Link Set with L_STATUS equal to SYMMETRIC (in other
   words: if the Source Address is a symmetric neighbor interface) then
   the 2-hop Neighbor Set SHOULD be updated as follows:

   1.  for each address (henceforth: 2-hop neighbor address), listed in
       the HELLO message:

       1.  if the 2-hop neighbor address is an interface address of the
           receiving node silently discard the 2-hop neighbor address
           (in other words: a node is not its own 2-hop neighbor).

       2.  else if the 2-hop neighbor address has a TLV with:

           +  (Type=LINK_STATUS, Value == SYMMETRIC); OR

           +  (Type=OTHER_IF, Value=SYMMETRIC);

           a 2-hop tuple is created with:





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           +  N2_local_iface_addr    = address of the interface over
              which the HELLO message was received;

           +  N2_neighbor_iface_addr = source address of the message;

           +  N2_2hop_iface_addr     = 2-hop neighbor address;

           +  N2_time                = current time + validity time.

           This tuple may replace an older similar tuple with the same
           N2_local_iface_addr, N2_neighbor_iface_addr and
           N2_2hop_iface_addr values.

       3.  else if the 2-hop neighbor address has a TLV with:

           +  (Type == LINK_STATUS, Value == LOST); OR

           +  (Type == OTHER_IF, Value == LOST),

           then any 2-hop tuple with:

           +  N2_local_iface_addr equal to the address of the interface
              over which the HELLO message was received; AND

           +  N2_neighbor_iface_addr equal to the source address of the
              message; AND

           +  and N2_2hop_iface_addr equal to the 2-hop neighbour
              address

           MUST be deleted.


8.3  Populating the MPR Selector Set

   Upon receiving a HELLO message, if a node finds one of its own
   interface addresses, listed with an MPR TLV (indicating that the
   originator node has selected one of the receiving node's interfaces
   as MPR), the MPR Selector Set SHOULD be updated as follows:

   For each address in the Local Interface Block of the received
   message:

   1.  If there exists no MPR Selector tuple with:

       *  MS_if_addr   == that address

       then a new tuple is created with:



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       *  MS_if_addr   =  that address

   2.  The tuple (new or otherwise) with:

       *  MS_if_addr   == that address

       is then modified as follows:

       *  MS_time       =  current time + validity time.

   MPR Selector tuples are removed upon expiration of MS_time, or upon
   link breakage as described in Section 8.4.

8.4  Neighborhood and 2-Hop Neighborhood Changes

   A change in the neighborhood is detected when:

   o  Link Loss: the L_SYM_time field of a link tuple expires (either
      due to time out, or as a result of processing a TLV (Type ==
      LINK_STATUS, Value == LOST)).

   o  Link Acquisition: a new link tuple is inserted in the Link Set
      with a non expired L_SYM_time or a tuple with expired L_SYM_time
      is modified so that L_SYM_time becomes non-expired.  This is
      considered as a link acquisition if there was previously no such
      link tuple.

   o  Neighbor Loss: all links to a neighbor node have have been lost.

   A change in the 2-hop neighborhood is detected when a 2-Hop Neighbor
   Tuple expires or is deleted according to section Section 8.2.

   The following processing occurs when changes in the neighborhood or
   the 2-hop neighborhood are detected:

   o  In case of link loss, all 2-Hop Neighbor Tuples with

      *  N2_local_iface_addr == interface address of the node where the
         link was lost

      *  N2_neighbor_iface_addr == interface address of the neighbor

      MUST be deleted.

   o  In case of neighbor loss, all MPR Selector tuples associated with
      that neighbor are deleted.  More precisely:





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      *  all MPR selector tuples with MS_iface_addr == interface address
         of the neighbor MUST be deleted, along with any interface
         addresses associated in the Neighbor Address Association Set.

   o  The MPR Set MUST be re-calculated when a link acquisition or loss
      is detected, or when a change in the 2-hop neighborhood is
      detected.

   o  An additional HELLO message MAY be sent when the MPR Set or the
      neighborhood changes.

   Additionally, proper update of the sets describing local topology
   should be made when a Neighbor Association Address Tuple has a list
   of addresses which is modified.





































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9.  TC Message Generation

   TC messages are, in OLSRv2, transmitted with the purpose of
   populating the Topology Set, the Attached Network Set and the
   Neighborhood Address Association Set:

   o  Topology Discovery: ensure that information is present in each
      node describing all destinations and a sufficient subset of links
      in order to provide least-hop paths to all destinations.

   o  Multiple Interface Declaration: ensure that nodes, up to two hops
      away from the originator, are aware of the interface configuration
      of the originator node.

   Thus, nodes with a non-empty Advertised Neighbor Set, or which are
   specifically reporting an empty Advertised Neighbor Set (for a period
   of T_HOLD_TIME following reporting a non-empty Advertised Neighbor
   Set) or with more than one interface which supports OLSRv2 and
   participates in the MANET, MUST generate TC messages, according to
   the following:

   1.  The node includes, in its first address block of the TC message,
       a Local Interface Block as specified in Section 6.2

   2.  If the node has a non-empty Advertised Neighbor Set or is
       specifically reporting an empty Advertised Neighbor Set, or it
       has a one or more attached non-OLSRv2 networks, to which it
       wishes to advertise routes to the network, it furthermore:

       1.  includes a message TLV (Type = CONTENT_SEQ_NUMBER TLV, Value
           = the Advertised Neighbor Set Sequence Number);

       2.  includes address blocks, containing its Advertised Neighbor
           Set (if non-empty);

       3.  includes address blocks and PREFIX_LENGTH TLVs, describing
           attached non-OLSRv2 networks;

       4.  sets the TTL of the message to the network diameter.

   3.  Otherwise, the node:

       1.  sets the TTL of the message to 2.

   OLSRv2 TC messages are generated and transmitted periodically, with a
   default interval between two consecutive TC emissions by the same
   node of TC_INTERVAL.




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9.1  TC Message: Transmission

   Messages are retransmitted in the packet/message format specified by
   [4] with the All-OLSRv2-Multicast address as destination IP address
   and is forwarded according to the specification in section
   Section 4.4.  If fragmentation is necessary, a FRAGMENTATION TLV MUST
   be included, and each fragment SHOULD be flagged as partially or
   wholly self contained as specified in [4].











































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10.  TC Message Processing

   Upon receiving a TC message, a node MUST update its topology
   information base according to the specification given in this
   section.

   For the purpose of this section, note the following:

   o  the "validity time" of a message is calculated from the
      VALIDITY_TIME message TLV according to the specification in
      Section 16;

   o  the "originator address" refers to the address, contained in the
      "originator address" field of the OLSRv2 message header specified
      in [4];

   o  the ASSN of the node, originating the TC message, is recovered as
      the value of the CONTENT_SEQ_NO message TLV in the TC message, if
      any.


10.1  Checking Freshness & Validity of a TC message

   In order to be able to ensure that only valid and fresh information
   is recorded in the Topology Set, each node maintains an ASSN History
   Set, recording the highest ASSN received from each node in the
   network, in the form of a "ASSN History Tuples":

       (AS_Address, AS_seq, AS_time)

   AS_Address is the originator address of a received TC message;

   AS_seq is the highest received ASSN seen in a TC message from
      AS_Address;

   AS_time is the time at which this tuple expires and MUST be removed.

   Upon receiving a TC message, a node MUST check if the TC message is
   fresh and valid as follows:

   1.  If the TC message has more than one address block (i.e. not just
       a Local Interface Block) and does not contain a message-TLV of
       type CONTENT_SEQ_NO. then the message MUST be discarded;

   2.  otherwise, if the ASSN History Set contains a tuple where:

       *  AS_Address == Originator Address of the TC message; AND




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       *  AS_seq > the ASSN recovered from the TC message,

       then the TC message MUST be discarded;

   3.  otherwise a tuple is inserted in the ASSN History Set with:

       *  AS_Address = Originator Address in the message;

       *  AS_seq = The ASSN, extracted from the message;

       *  AS_time = current time + AS_HOLD_TIME.

       possibly replacing an existing tuple with the same AS_Address.


10.2  Updating the Topology Set

   A node SHOULD update its Topology Set as follows:

   1.  For each address, LocAddr, from the Local Interface Block in the
       TC message:

       1.  For each advertised neighbor address, listed in an address
           block other than the Local Interface Block in the TC message,
           which does NOT have an associated PREFIX_LENGTH TLV:

           1.  if there exists a tuple in the Topology Set where:

               T_dest_iface_addr == advertised neighbor address; AND

               T_last_iface_addr == LocAddr.

               then the tuple is updated as follows:

               T_time = current time + validity time

               T_seq = ASSN

           2.  Otherwise, a new topology tuple is created with:

               T_dest_iface_addr = advertised neighbor address, AND

               T_last_iface_addr = LocAddr; AND

               T_seq = ASSN.






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10.3  Purging Old Entries from the Topology Set

   Old entries from the Topology Set MUST be purged as follows:

   1.  For each address, LocAddr, from the Local Interface Block in the
       TC message:

       1.  all tuples in the Topology Set where:

           T_last_iface_addr == LocAddr AND

           T_seq < ASSN

           MUST be removed.


10.4  Updating the Attached Networks Set

   A node SHOULD update its Attached Networks Set as follows:

   1.  For each address, LocAddr, from the Local Interface Block in the
       TC message:

       1.  For each advertised neighbor address, listed in an address
           block other than the Local Interface Block in the TC message,
           which does have an associated PREFIX_LENGTH TLV:

           1.  if there exists a tuple in the Attached Networks Set
               where:

               AN_net_addr == advertised neighbor address; AND

               AN_prefix_length == the prefix length as recoveredf from
                  the PREFIX_LENGTH TLV; AND

               AN_gw_addr == LocAddr.

               then the tuple is updated as follows:

               AN_time = current time + validity time

               AN_seq = ASSN

           2.  Otherwise, a new topology tuple is created with:







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               AN_net_addr == advertised neighbor address; AND

               AN_prefix_length == the prefix length as recoveredf from
                  the PREFIX_LENGTH TLV; AND

               AN_gw_addr == LocAddr.

               AN_time = current time + validity time

               AN_seq = ASSN


10.5  Purging Old Entries from the Attached Network Set

   TBD

10.6  Processing Unfragmented TC Messages

   If an unfragmented TC message, i.e. a TC message without a
   FRAGMENTATION message TLV, is received, it MUST be processed as
   follows:

   1.  Verify freshness and validity of the TC message (see
       Section 10.1).  If the message is not discarded, then continue;

   2.  Update the Topology Set (see Section 10.2);

   3.  Purge old entries from the Topology Set (see Section 10.3);

   4.  Update the Attached Networks Set (see Section 10.4;

   5.  Purge old entries from the Attached Networks Set (see
       Section 10.5);

   6.  Update the Neighborhood Address Association Set (see Section 13).


10.7  Processing Partially or Wholly Self-Contained Fragmented TC
      Messagess

   If a TC message contains a FRAGMENTATION message TLV which indicates
   that the fragment is a partially or wholly self-contained message,
   then the following processing SHOULD be carried out immediately upon
   receipt of each received fragment (if not then it MUST be carried out
   for each fragment once all fragments have been received):

   1.  Verify freshness and validity of the TC message (see
       Section 10.1).  If the message is not discarded, then continue;



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   2.  Update the Topology Set (see Section 10.2);

   3.  Update the Neighborhood Address Association Set (see Section 13).

   4.  Update the Attached Networks Set (see Section 10.4;

   Once all fragments have been received, the following processing MUST
   be carried out once:

   1.  Purge old entries from the Topology Set (see Section 10.3);

   2.  Purge old entries from the Attached Networks Set (see
       Section 10.5);






































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11.  Populating the MPR Set

   Each node MUST select, from among its one-hop neighbors, a subset of
   nodes as MPRs.  This subset MUST be selected such that a message
   transmitted by the node, and retransmitted by all its MPR nodes, will
   be received by all nodes 2 hops away.

   Each node selects its MPR Set individually, utilizing the information
   in the Link Set, 2-Hop Neighbor Set and Neighborhood Address
   Association Set. Initially these sets will be empty, as will be the
   MPR Set. A node SHOULD recalculate its MPR Set when a relevant change
   is made to the Link Set, 2-Hop Neighbor Set or Neighborhood Address
   Association Set.

   More specifically, a node MUST calculate MPRs per interface, the
   union of the MPR Sets of each interface make up the MPR Set for the
   node.

   MPRs are used to flood control messages from a node into the network
   while reducing the number of retransmissions that will occur in a
   region.  Thus, the concept of MPR is an optimization of a classical
   flooding mechanism.  While it is not essential that the MPR Set is
   minimal, it is essential that all strict 2-hop neighbors can be
   reached through the selected MPR nodes.  A node MUST select an MPR
   Set such that any strict 2-hop neighbor is covered by at least one
   MPR node.  A node MAY select additional MPRs beyond the minimum set.
   Keeping the MPR Set small ensures that the overhead of OLSRv2 is kept
   at a minimum.

   Appendix A contains an example heuristic for selecting MPRs.





















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12.  Populating Derived Sets

   The Relay Set and the Advertised Neighbor Set of OLSRv2 are denoted
   derived sets, since updates to these sets are not directly a function
   of message exchanges, but rather are derived from updates to other
   sets, in particular the MPR Selector Set.

12.1  Populating the Relay Set

   The Relay Set contains the set of neighbor addresses, for which a
   node is supposed to relay broadcast traffic.  This set SHOULD at
   least contain the addresses of the MPR Selector set (i.e. all
   addresses, associated with a MPR selector through the Neighborhood
   Address Association Set).  This set MAY contain additional neighbor
   addresses.

12.2  Populating the Advertised Neighbor Set

   The Advertised Neighbor Set contains the set of neighbor addresses,
   to which a node advertises links through TC messages.  This set
   SHOULD at least contain the addresses of the MPR Selector Set (i.e.
   all addresses, associated with a MPR selector through the
   Neighborhood Address Association Set).  This set MAY contain
   additional neighbor addresses.

   Each time an address is removed from the Advertised Neighbor Set, the
   ASSN MUST be incremented.  When an address is added to the Advertised
   Neighbor Set, the ASSN MUST be incremented.























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13.  Populating the Neighborhood Address Association Set

   All OLSRv2 messages containing a Local Interface Block (including
   HELLO and TC messages) SHOULD be used to update the Neighborhood
   Address Association Set as follows:

   1.  If there is a Neighborhood Address Association Tuple, any of
       whose addresses are in the Local Interface Block being processed,
       then discard that tuple.

   2.  A tuple is added to the Neighborhood Address Association Set,
       where:

       *  NA_neighbor_addr_list = all addresses from the Local Interface
          Block;

       *  NA_time = current time + NA_HOLD_TIME.


































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14.  Routing Table Calculation

   The Routing Set is updated when a change (an entry appearing/
   disappearing) is detected in:

   o  the Link Set,

   o  the Neighbor Address Association Set,

   o  the 2-hop Neighbor Set,

   o  the Topology Set,

   Updates to the Routing Set does not generate or trigger any messages
   to be transmitted.  The state of the Routing Set SHOULD, however, be
   reflected in the IP routing table by adding and removing entries from
   the routing table as appropriate.

   To construct the Routing Set of node X, a shortest path algorithm is
   run on the directed graph containing the arcs X -> Y where Y is any
   symmetric neighbor of X (with Link Type equal to SYM), the arcs Y ->
   Z where Y is a neighbor node with willingness different of WILL_NEVER
   and there exists an entry in the 2-hop Neighbor Set with Y as
   N2_neighbor_iface_addr and Z as N2_2hop_iface_addr, and the arcs U ->
   V, where there exists an entry in the Topology Set with V as
   T_dest_iface_addr and U as T_last_iface_addr.  The graph is
   complemented with the arcs W0 -> W1 where W0 and W1 are two addresses
   of interfaces of a same neighbor (in a neighbor address association
   tuple).

   The following procedure is given as an example for (re-)calculating
   the Routing Set (with a breadth-first algorithm):

   1.  All the tuples from the Routing Set are removed.

   2.  The new routing tuples are added starting with the symmetric
       neighbors (h=1) as the destinations.  Thus, for each tuple in the
       Link Set where:

       *  L_STATUS           == SYMMETRIC (L_STATUS is calculated as
          indicated in Table 1)

       a new routing tuple is recorded in the Routing Set with:

       *  R_dest_iface_addr  = L_neighbor_iface_addr, of the link tuple;

       *  R_next_iface_addr  = L_neighbor_iface_addr, of the link tuple;




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       *  R_dist             = 1;

       *  R_iface_addr       = L_local_iface_addr of the link tuple.

   3.  for each neighbor address association tuple, for which two
       addresses A1 and A2 exist in I_neighbor_iface_addr_list where:

       *  there exists a routing tuple with:

          +  R_dest_iface_addr == A1

       *  there is no routing tuple with:

          +  R_dest_iface_addr == A2

       then a tuple in the Routing Set is created with:

       *  R_dest_iface_addr = A2;

       *  R_next_iface_addr = R_next_iface_addr of the route tuple of
          A1;

       *  R_dist            = R_dist of the route tuple of A1 (e.g. 1);

       *  R_iface_addr      = R_iface_addr of the route tuple of A1.

   4.  for each symmetric strict 2-hop neighbor where the
       N2_neighbor_iface_addr has a willingness different from
       WILL_NEVER a tuple in the Routing Set is created with:

       *  R_dest_iface_addr = N2_2hop_iface_addr of the 2-hop neighbor;

       *  R_next_iface_addr = the R_next_iface_addr of the route tuple
          with:

          +  R_dest_iface_addr == N2_neighbor_iface_addr of the 2-hop
             tuple;

       *  R_dist            = 2;

       *  R_iface_addr      = the R_iface_addr of the route tuple with:

          +  R_dest_iface_addr == N2_neighbor_iface_addr of the 2-hop
             tuple;

   5.  The new route tuples for the destination nodes h+1 hops away are
       recorded in the routing table.  The following procedure MUST be
       executed for each value of h, starting with h=2 and incrementing



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       by 1 for each iteration.  The execution will stop if no new tuple
       is recorded in an iteration.

       1.  For each topology tuple in the Topology Set, if its
           T_dest_iface_addr does not correspond to R_dest_iface_addr of
           any route tuple in the Routing Set AND its T_last_iface_addr
           corresponds to R_dest_iface_addr of a route tuple whose
           R_dist is equal to h, then a new route tuple MUST be recorded
           in the Routing Set (if it does not already exist) where:

           +  R_dest_iface_addr = T_dest_iface_addr;

           +  R_next_iface_addr = R_next_iface_addr of the route tuple
              where:

              -  R_dest_iface_addr == T_last_iface_addr

           +  R_dist           = h+1; and

           +  R_iface_addr     = R_iface_addr of the route tuple where:

              -  R_dest_iface_addr == T_last_iface_addr.

       2.  Several topology tuples may be used to select a next hop
           R_next_iface_addr for reaching the node R_dest_iface_addr.
           When h==1, ties should be broken such that nodes with highest
           willingness and MPR selectors are preferred as next hop.
























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15.  Proposed Values for Constants

   This section list the values for the constants used in the
   description of the protocol.

15.1  Message Intervals

   o  HELLO_INTERVAL        = 2 seconds

   o  REFRESH_INTERVAL      = 2 seconds

   o  TC_INTERVAL           = 5 seconds


15.2  Holding Times

   o  L_HOLD_TIME           = 3 x HELLO_INTERVAL

   o  N2_HOLD_TIME          = 3 x REFRESH_INTERVAL

   o  NA_HOLD_TIME          = 3 x TC_INTERVAL

   o  T_HOLD_TIME           = 3 x TC_INTERVAL

   o  RX_HOLD_TIME          = 30 seconds

   o  FW_HOLD_TIME          = 30 seconds

   o  P_HOLD_TIME           = 30 seconds

   o  FG_HOLD_TIME          = 30 seconds


15.3  Willingness

   o  WILL_NEVER            = 0

   o  WILL_LOW              = 1

   o  WILL_DEFAULT          = 3

   o  WILL_HIGH             = 6

   o  WILL_ALWAYS           = 7







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15.4  Time

   o  C                 = 0.0625 seconds (1/16 second)
















































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16.  Representing Time

   OLSRv2 specifies several TLVs, where time, in seconds, is to be
   represented via an 8 bit field.

   Of these 8 bits, the highest four bits represent the mantissa (a) and
   the four lowest bits represent the exponent (b), yielding that:

   o  time = C*(1+a/16)* 2^b  [in seconds]

   where a is the integer represented by the four highest bits of the
   time field and b the integer represented by the four lowest bits of
   the time field.  The proposed value of the scaling factor C is
   specified in Section 15.  All nodes in the network MUST use the same
   value of C.




































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17.  IANA Considerations

17.1  Multicast Addresses

   A well-known multicast address, All-OLSRv2-Multicast, must be
   registered and defined for both IPv6 and IPv4.  The addressing scope
   is link-local, i.e. this address is similar to the all nodes/routers
   multicast address of IPv6 in that it targets all OLSRv2 capable nodes
   adjacent to the originator of an IP datagram.

17.2  Message Types

   OLSRv2 defines two message types, which must be allocated from the
   "Assigned Message Types" repository of [4]

   +--------------------+--------+-------------------------------------+
   |      Mnemonic      |  Value | Description                         |
   +--------------------+--------+-------------------------------------+
   |       HELLOv2      |   TBD  | Local Signaling                     |
   |                    |        |                                     |
   |        TCv2        |   TBD  | Global Signaling                    |
   +--------------------+--------+-------------------------------------+

                                  Table 7


17.3  TLV Types

   OLSRv2 defines three Message TLV types, which must be allocated from
   the "Assigned message TLV Types" repository of [4]

   +--------------------+--------+-------------------------------------+
   |      Mnemonic      |  Value | Description                         |
   +--------------------+--------+-------------------------------------+
   |    VALIDITY_TIME   |   TBD  | The time (in seconds) from receipt  |
   |                    |        | of the message during which the     |
   |                    |        | information contained in a message  |
   |                    |        | is to be valid                      |
   |                    |        |                                     |
   |    INTERVAL_TIME   |   TBD  | The time (in seconds) between two   |
   |                    |        | successive transmissions of         |
   |                    |        | messages of a given type            |
   |                    |        |                                     |
   |     WILLINGNESS    |   TBD  | Specifies a node's willingness      |
   |                    |        | [0-7] to act as a relay and to      |
   |                    |        | partake in network formation        |
   +--------------------+--------+-------------------------------------+




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                                  Table 8

   OLSRv2 defines three Address Block TLV types, which must be allocated
   from the "Assigned address block TLV Types" repository of [4]

   +--------------------+--------+-------------------------------------+
   |      Mnemonic      |  Value | Description                         |
   +--------------------+--------+-------------------------------------+
   |      OTHER_IF      |   TBD  | Specifies that an address is        |
   |                    |        | associated to an interface other    |
   |                    |        | than the one where the message is   |
   |                    |        | transmitted, and may specify its    |
   |                    |        | status (verified bidirectional or   |
   |                    |        | lost)                               |
   |                    |        |                                     |
   |     LINK_STATUS    |   TBD  | Specifies a given link's status     |
   |                    |        | (asymmetric, verified               |
   |                    |        | bidirectional, lost)                |
   |                    |        |                                     |
   |         MPR        |   TBD  | Specifies that a given address is   |
   |                    |        | selected as MPR                     |
   +--------------------+--------+-------------------------------------+

                                  Table 9


18.  References

   [1]  Clausen, T., "The Optimized Link State Routing Protocol",
        RFC 3626, October 2003.

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

   [3]  Atkins, D., Stallings, W., and P. Zimmermann, "PGP Message
        Exchange Formats", RFC 1991, August 1996.

   [4]  Clausen, T., Dean, J., and C. Dearlove, "Generalized MANET
        Packet/Message Format", Work In
        Progress draft-ietf-manet-packetbb-00.txt, February 2006.

   [5]  ETSI, "ETSI STC-RES10 Committee.  Radio equipment and systems:
        HIPERLAN type 1, functional specifications ETS 300-652",
        June 1996.

   [6]  Jacquet, P., Minet, P., Muhlethaler, P., and N. Rivierre,
        "Increasing reliability in cable free radio LANs: Low level
        forwarding in HIPERLAN.", 1996.



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   [7]  Qayuum, A., Viennot, L., and A. Laouiti, "Multipoint relaying:
        An efficient technique for flooding in mobile wireless
        networks.", 2001.


Authors' Addresses

   Thomas Heide Clausen
   LIX, Ecole Polytechnique, France

   Phone: +33 6 6058 9349
   Email: T.Clausen@computer.org
   URI:   http://www.lix.polytechnique.fr/Labo/Thomas.Clausen/


   Christopher M. Dearlove
   BAE Systems Advanced Technology Centre

   Phone: +44 1245 242194
   Email: chris.dearlove@baesystems.com


   The OLSRv2 Design Team
   MANET Working Group



























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Appendix A.  Example Heuristic for Calculating MPRs

   The following specifies a proposed heuristic for selection of MPRs.

   In graph theory terms, MPR computation is a "set cover" problem,
   which is a difficult optimization problem, but for which an easy and
   efficient heuristics exist: the so-called "Greedy Heuristic", a
   variant of which is described here.  In simple terms, MPR computation
   constructs an MPR Set that enables a node to reach any 2-hop
   interfaces by relaying through an MPR node.

   There are several peripheral issues that the algorithm need to
   address.  The first one is that some nodes have some willingness
   WILL_NEVER.  The second one is that some nodes may have several
   interfaces.

   The algorithm hence need to be precised in the following way:

   o  All neighbor nodes with willingness equal to WILL_NEVER MUST
      ignored in the following algorithm: they are not considered as
      neighbors (hence not used as MPRs), nor as 2-hop neighbors (hence
      no attempt to cover them is made).

   o  Because link sensing is performed by interface, the local network
      topology, is best described in terms of links: hence the algorithm
      is considering neighbor interfaces, and 2-hop neighbor interfaces
      (and their addresses).  Additionally, asymmetric links are
      ignored.  This is reflected in the definitions below.

   o  MPR computation is performed on each interface of the node: on
      each interface I, the node MUST select some neighbor interfaces,
      so that all 2-hop interfaces are reached.

   From now on, MPR calculation will be described for one interface I on
   the node, and the following terminology will be used in describing
   the heuristics:

   neighbor interface (of I) - An interface of a neighbor to which there
      exist a symmetrical link on interface I.

   N  - the set of such neighbor interfaces

   2-hop neighbor interface (of I) An interface of a symmetric strict
      2-hop neighbor and which can be reached from a neighbor interface
      for I.






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   N2 - the set of such 2-hop neighbor interfaces

   D(y): - the degree of a 1-hop neighbor interface y (where y is a
      member of N), is defined as the number of symmetric neighbor
      interfaces of node y which are in N2

   MPR Set - the set of the neighbor interfaces selected as MPRs.

   The proposed heuristic selects iteratively some interfaces from N as
   MPRs in order to cover 2-hop neighbor interfaces from N2, as follows:

   1.  Start with an MPR Set made of all members of N with N_willingness
       equal to WILL_ALWAYS

   2.  Calculate D(y), where y is a member of N, for all interfaces in
       N.

   3.  Add to the MPR Set those interfaces in N, which are the *only*
       nodes to provide reachability to an interface in N2.  For
       example, if interface B in N2 can be reached only through a
       symmetric link to interface A in N, then add interface B to the
       MPR Set. Remove the interfaces from N2 which are now covered by a
       interface in the MPR Set.

   4.  While there exist interfaces in N2 which are not covered by at
       least one interface in the MPR Set:

       1.  For each interface in N, calculate the reachability, i.e.,
           the number of interfaces in N2 which are not yet covered by
           at least one node in the MPR Set, and which are reachable
           through this neighbor interface;

       2.  Select as an MPR the interface with highest N_willingness
           among the interfaces in N with non-zero reachability.  In
           case of multiple choice select the interface which provides
           reachability to the maximum number of interfaces in N2.  In
           case of multiple interfaces providing the same amount of
           reachability, select the interface as MPR whose D(y) is
           greater.  Remove the interfaces from N2 which are now covered
           by an interface in the MPR Set.

   Other algorithms, as well as improvements over this algorithm, are
   possible.  For example:

   o  Some 2-hop neighbors may have several interfaces.  The described
      algorithm attempts to reach every such interface of the nodes.
      However, whenever information that several 2-hop interfaces are,
      in fact, interfaces of the same 2-hop neighbor, is available, it



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      can be used: only one of the interfaces of the 2-hop neighbor
      needs to be covered.  This information is provided in the
      Neighborhood Address Association Set.

   o  Assume that in a multiple interface scenario there exists more
      than one link between nodes 'a' and 'b'.  If node 'a' has selected
      node 'b' as MPR for one of its interfaces, then node 'b' can be
      selected as MPR with minimal performance loss by any other
      interfaces on node 'a'.

   o  In a multiple interface scenario MPRs are selected for each
      interface of the selecting node, providing full coverage of all
      2-hop nodes accessible through that interface.  The overall MPR
      Set is then the union of these sets.  These sets do not however
      have to be selected independently, if a node is selected as an MPR
      for one interface it may be automatically added to the MPR
      selection for other interfaces.


































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Appendix B.  Example Algorithms for Generating Control Traffic

   The proposed generation of the control messages proceeds in four
   steps.  HELLO messages and TC messages both essentially consist of a
   list of advertised addresses of neighbors (some part of the
   topology).

   Hence, a first step is to collect the set of relevant addresses which
   are to be advertised.  Because there are a number of TLVs which can
   be associated with each address (including mandatory ones), this step
   results in a list of addresses, each associated with a certain number
   of TLVs.

   The second step is then to regroup the addresses which share exactly
   the same TLVs (same Type and same Value), into an address block which
   will be associated with a list of TLVs.

   The third step is to pack the message header and message TLVs into a
   sequence of octets.

   The fourth step consists of packing every address block obtained in
   the second step by finding the longest common prefix of the addresses
   in the address block (the head), then, packing the list of the tails
   of the addresses into a sequence of octets, followed by the TLVs of
   the address block.

   This generation method can be used for TC generation and HELLO
   generation: in each case, all what need to be specified is the
   message headers, message TLVs, and the list of each address with its
   associated TLVs.

   The Local Interface Block MUST include all of the participating
   interface addresses of the node (including the one of chosen as the
   node's originator address and included in the message header).

Appendix B.1  Example Algorithm for Generating HELLO messages

   This section proposes an algorithm for generating HELLO messages.
   Periodically, on each interface I, the node generates a HELLO message
   specific to that interface, as follows:

   1.  First, the list of the links of the interface is collected.  It
       is the list of the Link Tuples where:

       *  L_local_iface_addr == address of the interface

       Each corresponding address L_neighbor_iface_addr is then
       advertised with the following TLVs:



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       *  Type="LINK-STATUS", Value=L_STATUS, the status of the link
          (see Section 5.1.1);

       *  Type="OTHER_IF", if and only if as specified in Section 7);

       *  Type="MPR", if and only of the address L_neighbor_iface_addr
          is an interface address in the MPR Set.

   2.  Second, if the node has more than one interface, for each address
       which was not previously advertised and for which there exists a
       Link Tuple on another interface where:

       *  L_local_iface_addr is different from address of the interface
          I; AND

       *  L_STATUS == SYMMETRIC

       the corresponding address L_neighbor_iface_addr is advertised
       with the following TLV:

       *  Type="OTHER_IF", Value=SYMMETRIC.

   3.  Third, if the node has more than one interface, for each
       interface address which is to be reported as LOST as specified in
       Section 7) the interface address is advertised with the following
       TLV:

       *  Type="OTHER_IF", Value=LOST.

   4.  Then a HELLO message is generated using the previous method, with
       the specified headers and TLVs:

       *  a message TLV with Type="VALIDITY_TIME" and Value=encoding of
          L_HOLD_TIME, SHALL be added

       *  a message TLV with Type="INTERVAL_TIME" and Value=encoding of
          HELLO_INTERVAL, SHOULD be added

       *  a message TLV with Type="WILLINGNESS" and Value=the
          willingness of the node.  This SHOULD NOT be included if this
          value is WILL_DEFAULT, it SHALL be included otherwise.


Appendix B.2  Example Algorithm for Generating TC messages

   Periodically, the node generates TC messages, broadcast on all the
   interfaces of the node, as follows:




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   1.  Each A_iface_addr in the Advertised Neighbor Set, SHALL be
       included in the TC message.

   2.  The TC message is generated with the proper headers, and (except
       where the Advertised Neighbor Set is empty and the TC message is
       not specifically reporting this, see Section 9) including the
       message TLV, Type="CONTENT_SEQUENCE_NUMBER", Value=the current
       ASSN of the node.











































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Appendix C.  Protocol and Port Number

   Packets in OLSRv2 are communicated using UDP.  Port 698 has been
   assigned by IANA for exclusive usage by the OLSR (v1 and v2)
   protocol.














































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Appendix D.  Packet and Message Layout

   This section specifies the translation from the abstract descriptions
   of packets employed in the protocol specification, and the bit-layout
   packets actually exchanged between the nodes.

Appendix D.1  OLSRv2 Packet Format

   The basic layout of an OLSRv2 packet is as described in [4].  However
   the following points should be noted.

   OLSRv2 uses only packets with a packet header.  Thus all OLSRv2
   packets have the following layout.




      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

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |0 0 0 0 0 0 0 0|   Reserved    |    Packet Sequence Number     |

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |                                                               |

     |                            Message                            |

     |                                                               |

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |                                                               |

     :                              ...                              :

     |                                                               |

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |                                                               |

     |                            Message                            |

     |                                                               |



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     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+




   All reserved bits are also unset (zero).

   OLSRv2 uses only packets with a complete message header.  Thus all
   OLSRv2 messages have the following layout.




      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

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |  Message Type | Resv  |U|N|0|0|         Message Size          |

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |                      Originator Address                       |

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |  Time To Live |   Hop Count   |    Message Sequence Number    |

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |                                                               |

     |                    Message Body + Padding                     |

     |                                                               |

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+




   In standard OLSRv2 messages (HELLO and TC) the U and N bits are also
   unset(zero).  In all OLSRv2 messages the reserved bits marked Resv
   above are also unset (zero).

   The layouts of the message body, address block, TLV block and TLV are
   as in [4], allowing all options.  Standard (HELLO and TC) messages



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   contain a first address block which contains local interface
   addresses, all other address blocks contain information specific to
   the message type.  Except by being first, the local interface address
   block is not distinguished in any way.

   An example HELLO message, using IPv4 (four octet) addresses is as
   follows.  The overall message length is 56 octets (it does not need
   padding).  The message has a TTL of 1 and a hop count of 0, as sent
   by its originator.

   The message has a message TLV block with content length 12 octets
   containing three message TLVs.  These TLVs represent message validity
   time, message interval time and willingness.  Each uses a TLV with
   semantics value 4, indicating no start and stop indexes are included,
   and each has a value length of 1 octet.

   The first address block contains a single local interface address,
   with head length 4; thus although 1 tail is indicated, no tail octets
   are included.  This address block has no TLVs (TLV block content
   length 0 octets).

   The second, and last, address block reports 4 neighbour interface
   addresses, with address head length 3 octets.  The following TLV
   block (content length 11 octets) includes two TLVs.

   The first of these TLVs reports the link status of all four
   neighbours in a single multivalue TLV, the first two addresses are
   HEARD, the last two addresses are SYMMETRIC.  The TLV semantics value
   of 12 indicates, in addition to that this is a multivalue TLV, that
   no start index and stop index are included, since values for all
   addresses are included.  The TLV value length of 4 octets indicates
   one octet per value per address.

   The second of these TLV indicates that the last address (start index
   3, stop index 3) is an MPR.  This TLV has no value, or value length,
   fields, as indicated by its semantics octet being equal to 1.




      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

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |     HELLO     |0 0 0 0 0 0 0 0|0 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0|




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     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |                      Originator Address                       |

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |0 0 0 0 0 0 0 1|0 0 0 0 0 0 0 0|    Message Sequence Number    |

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0| VALIDITY-TIME |0 0 0 0 0 1 0 0|

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |0 0 0 0 0 0 0 1|     Value     | INTERVAL-TIME |0 0 0 0 0 1 0 0|

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |0 0 0 0 0 0 0 1|     Value     |  WILLINGNESS  |0 0 0 0 0 1 0 0|

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |0 0 0 0 0 0 0 1|     Value     |0 0 0 0 0 1 0 0|     Head      |

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |                  Head (cont)                  |0 0 0 0 0 0 0 1|

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0|0 0 0 0 0 0 1 1|     Head      |

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |          Head (cont)          |0 0 0 0 0 1 0 0|     Tail      |

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |     Tail      |     Tail      |     Tail      |0 0 0 0 0 0 0 0|

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |0 0 0 0 1 0 1 1|  LINK-STATUS  |0 0 0 0 1 1 0 0|0 0 0 0 0 1 0 0|

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |     HEARD     |     HEARD     |   SYMMETRIC   |   SYMMETRIC   |




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     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |      MPR      |0 0 0 0 0 0 0 1|0 0 0 0 0 0 1 1|0 0 0 0 0 0 1 1|

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+




   An example TC message, using IPv4 (four octet) addresses, is as
   follows.  The overall message length is 67 octets, the final octet is
   padding.

   The message has a message TLV block with content length 13 octets
   containing three TLVs.  The first TLV is a content sequence number
   TLV used to carry the 2 octet ANSN.  The semantics value is 4
   indicating that no index fields are included.  The other two TLVs are
   validity and interval times as for the HELLO message above.

   The message has three address blocks.  The first address block
   contains 3 local interface addresses (with common head length 2
   octets) and has a TLV block with content length 4 octets containing a
   single TLV with semantics value 1, indicating that the TLV has no
   value field, or length thereof.  This TLV indicates that the second
   and third of these addresses (indexes 1 to 2) are for other
   interfaces than the one on which this TC message is transmitted.

   The other two address blocks contain neighbour interface addresses,
   with head lengths 2 and 4 respectively.  The first of these, with 3
   addresses, has an empty TLV block (content length 0 octets).  The
   second, which contains 1 address, has a TLV block (content length 4
   octets) with a single TLV (semantics value 4 indicating no indexes
   needed) indicating that this is a network address with the given
   prefix length (itself with length 1 octet).




      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

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |      TC       |0 0 0 0 0 0 0 0|0 0 0 0 0 0 0 0 0 1 0 0 0 0 1 1|

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+




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     |                      Originator Address                       |

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     | Time to Live  |   Hop Count   |    Message Sequence Number    |

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 1| CONT_SEQ_NUM  |0 0 0 0 0 1 0 0|

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |0 0 0 0 0 0 1 0|         Value (ASSN)          | VALIDITY_TIME |

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |0 0 0 0 0 1 0 0|0 0 0 0 0 0 0 1|     Value     | INTERVAL_TIME |

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |0 0 0 0 0 1 0 0|0 0 0 0 0 0 0 1|     Value     |0 0 0 0 0 0 1 0|

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |             Head              |0 0 0 0 0 0 1 1|     Tail      |

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |  Tail (cont)  |             Tail              |     Tail      |

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |  Tail (cont)  |0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0|   OTHER_IF    |

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |0 0 0 0 0 0 0 1|0 0 0 0 0 0 0 1|0 0 0 0 0 0 1 0|0 0 0 0 0 0 1 0|

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |             Head              |0 0 0 0 0 0 1 1|     Tail      |

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |  Tail (cont)  |             Tail              |     Tail      |

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+




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     |  Tail (cont)  |0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0|0 0 0 0 0 1 0 0|

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |                             Head                              |

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |0 0 0 0 0 0 0 1|0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0| PREFIX-LENGTH |

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |0 0 0 0 0 1 0 0|0 0 0 0 0 0 0 1|Value (Length) |0 0 0 0 0 0 0 0|

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+




































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Appendix E.  Node Configuration

   OLSRv2 does not make any assumption about node addresses, other than
   that each node is assumed to have at least one a unique and routable
   IP address for each interface that it has which participates in the
   MANET.

   When applicable, a recommended way of connecting an OLSRv2 network to
   an existing IP routing domain is to assign an IP prefix (under the
   authority of the nodes/gateways connecting the MANET with the routing
   domain) exclusively to the OLSRv2 area, and to configure the gateways
   statically to advertise routes to that IP sequence to nodes in the
   existing routing domain.






































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Appendix F.  Security Considerations

   Currently, OLSRv2 does not specify any special security measures.  As
   a proactive routing protocol, OLSRv2 makes a target for various
   attacks.  The various possible vulnerabilities are discussed in this
   section.

Appendix F.1  Confidentiality

   Being a proactive protocol, OLSRv2 periodically diffuses topological
   information.  Hence, if used in an unprotected wireless network, the
   network topology is revealed to anyone who listens to OLSRv2 control
   messages.

   In situations where the confidentiality of the network topology is of
   importance, regular cryptographic techniques, such as exchange of
   OLSRv2 control traffic messages encrypted by PGP [3] or encrypted by
   some shared secret key, can be applied to ensure that control traffic
   can be read and interpreted by only those authorized to do so.

Appendix F.2  Integrity

   In OLSRv2, each node is injecting topological information into the
   network through transmitting HELLO messages and, for some nodes, TC
   messages.  If some nodes for some reason, malicious or malfunction,
   inject invalid control traffic, network integrity may be compromised.
   Therefore, message authentication is recommended.

   Different such situations may occur, for instance:

   1.  a node generates TC messages, advertising links to non-neighbor
       nodes;

   2.  a node generates TC messages, pretending to be another node;

   3.  a node generates HELLO messages, advertising non-neighbor nodes;

   4.  a node generates HELLO messages, pretending to be another node;

   5.  a node forwards altered control messages;

   6.  a node does not forward control messages;

   7.  a node does not select multipoint relays correctly;

   8.  a node forwards broadcast control messages unaltered, but does
       not forward unicast data traffic;




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   9.  a node "replays" previously recorded control traffic from another
       node.

   Authentication of the originator node for control messages (for
   situations 2, 4 and 5) and on the individual links announced in the
   control messages (for situations 1 and 3) may be used as a
   countermeasure.  However to prevent nodes from repeating old (and
   correctly authenticated) information (situation 9) temporal
   information is required, allowing a node to positively identify such
   delayed messages.

   In general, digital signatures and other required security
   information may be transmitted as a separate OLSRv2 message type,
   thereby allowing that "secured" and "unsecured" nodes can coexist in
   the same network, if desired, or signatures and security information
   may be transmitted within the OLSRv2 HELLO and TC messages, using the
   TLV mechanism.

   Specifically, the authenticity of entire OLSRv2 control messages can
   be established through employing IPsec authentication headers,
   whereas authenticity of individual links (situations 1 and 3) require
   additional security information to be distributed.

   An important consideration is, that all control messages in OLSRv2
   are transmitted either to all nodes in the neighborhood (HELLO
   messages) or broadcast to all nodes in the network (TC messages).

   For example, a control message in OLSRv2 is always a point-to-
   multipoint transmission.  It is therefore important that the
   authentication mechanism employed permits that any receiving node can
   validate the authenticity of a message.  As an analogy, given a block
   of text, signed by a PGP private key, then anyone with the
   corresponding public key can verify the authenticity of the text.

Appendix F.3  Interaction with External Routing Domains

   OLSRv2 does, through the use of TC messages, provide a basic
   mechanism for injecting external routing information to the OLSRv2
   domain.  Appendix E also specifies that routing information can be
   extracted from the topology table or the routing table of OLSRv2 and,
   potentially, injected into an external domain if the routing protocol
   governing that domain permits.

   Other than as described in Appendix E, when operating nodes,
   connecting OLSRv2 to an external routing domain, care MUST be taken
   not to allow potentially insecure and untrustworthy information to be
   injected from the OLSRv2 domain to external routing domains.  Care
   MUST be taken to validate the correctness of information prior to it



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   being injected as to avoid polluting routing tables with invalid
   information.

   A recommended way of extending connectivity from an existing routing
   domain to an OLSRv2 routed MANET is to assign an IP prefix (under the
   authority of the nodes/gateways connecting the MANET with the exiting
   routing domain) exclusively to the OLSRv2 MANET area, and to
   configure the gateways statically to advertise routes to that IP
   sequence to nodes in the existing routing domain.

Appendix F.4  Node Identity

   OLSRv2 does not make any assumption about node addresses, other than
   that each node is assumed to have at least one a unique and routable
   IP address for each interface that it has which participates in the
   MANET.



































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Appendix G.  Flow and Congestion Control

   TBD
















































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Appendix H.  Sequence Numbers

   Sequence numbers are used in OLSR with the purpose of discarding
   "old" information, i.e., messages received out of order.  However
   with a limited number of bits for representing sequence numbers,
   wrap-around (that the sequence number is incremented from the maximum
   possible value to zero) will occur.  To prevent this from interfering
   with the operation of OLSRv2, the following MUST be observed.

   The term MAXVALUE designates in the following the largest possible
   value for a sequence number.

   The sequence number S1 is said to be "greater than" the sequence
   number S2 if:

   o  S1 > S2 AND S1 - S2 <= MAXVALUE/2 OR

   o  S2 > S1 AND S2 - S1 > MAXVALUE/2

   Thus when comparing two messages, it is possible - even in the
   presence of wrap-around - to determine which message contains the
   most recent information.





























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Appendix I.  Contributors

   This specification is the result of the joint efforts of the
   following contributers -- listed alphabetically.

   o  Cedric Adjih, INRIA, France, <Cedric.Adjih@inria.fr>

   o  Emmanuel Baccelli, Hitachi Labs Europe, France,
      <Emmanuel.Baccelli@inria.fr>

   o  Thomas Heide Clausen, PCRI, France<T.Clausen@computer.org>

   o  Justin Dean, NRL, USA<jdean@itd.nrl.navy.mil>

   o  Christopher Dearlove, BAE Systems, UK,
      <Chris.Dearlove@baesystems.com>

   o  Satoh Hiroki, Hitachi SDL, Japan, <h-satoh@sdl.hitachi.co.jp>

   o  Philippe Jacquet, INRIA, France, <Philippe.Jacquet@inria.fr>

   o  Monden Kazuya, Hitachi SDL, Japan, <monden@sdl.hitachi.co.jp>

   o  Kenichi Mase, University, Japan, <mase@ie.niigata-u.ac.jp>

   o  Ryuji Wakikawa, KEIO University, Japan, <ryuji@sfc.wide.ad.jp>

























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Appendix J.  Acknowledgements

   The authors would like to acknowledge the team behind OLSRv1,
   specified in RFC3626, including Anis Laouiti, Pascale Minet, Laurent
   Viennot (all at INRIA, France), and Amir Qayuum (Center for Advanced
   Research in Engineering) for their contributions.

   The authors would like to gratefully acknowledge the following people
   for intense technical discussions, early reviews and comments on the
   specification and its components: Kenichi Mase (Niigata University),
   Li Li (CRC), Louise Lamont (CRC), Joe Macker (NRL), Alan Cullen (BAE
   Systems), Philippe Jacquet (INRIA), Khaldoun Al Agha (LRI), Richard
   Ogier (?), Song-Yean Cho (Samsung Software Center), Shubhranshu Singh
   (Samsung AIT) and the entire IETF MANET working group.





































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