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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
Intended status: Standards Track                             C. Dearlove
Expires: October 22, 2010                                BAE Systems ATC
                                                              P. Jacquet
                                                 Project Hipercom, INRIA
                                                  The OLSRv2 Design Team
                                                     MANET Working Group
                                                          April 20, 2010


          The Optimized Link State Routing Protocol version 2
                       draft-ietf-manet-olsrv2-11

Abstract

   This document describes version 2 of the Optimized Link State Routing
   (OLSRv2) protocol for Mobile Ad hoc NETworks (MANETs).

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on October 22, 2010.

Copyright Notice

   Copyright (c) 2010 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   publication of this document.  Please review these documents
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   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of



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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
   10, 2008.  The person(s) controlling the copyright in some of this
   material may not have granted the IETF Trust the right to allow
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   it for publication as an RFC or to translate it into languages other
   than English.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  5
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  6
   3.  Applicability Statement  . . . . . . . . . . . . . . . . . . .  8
   4.  Protocol Overview and Functioning  . . . . . . . . . . . . . .  9
     4.1.  Overview . . . . . . . . . . . . . . . . . . . . . . . . .  9
     4.2.  Routers and Interfaces . . . . . . . . . . . . . . . . . . 11
     4.3.  Information Base Overview  . . . . . . . . . . . . . . . . 12
       4.3.1.  Local Information Base . . . . . . . . . . . . . . . . 12
       4.3.2.  Interface Information Bases  . . . . . . . . . . . . . 13
       4.3.3.  Neighbor Information Base  . . . . . . . . . . . . . . 13
       4.3.4.  Topology Information Base  . . . . . . . . . . . . . . 13
       4.3.5.  Received Message Information Base  . . . . . . . . . . 14
     4.4.  Signaling Overview . . . . . . . . . . . . . . . . . . . . 15
     4.5.  Routing Set  . . . . . . . . . . . . . . . . . . . . . . . 16
   5.  Protocol Parameters and Constants  . . . . . . . . . . . . . . 16
     5.1.  Protocol and Port Numbers  . . . . . . . . . . . . . . . . 17
     5.2.  Multicast Address  . . . . . . . . . . . . . . . . . . . . 17
     5.3.  Local History Times  . . . . . . . . . . . . . . . . . . . 17
     5.4.  Message Intervals  . . . . . . . . . . . . . . . . . . . . 17
     5.5.  Advertised Information Validity Times  . . . . . . . . . . 18
     5.6.  Received Message Validity Times  . . . . . . . . . . . . . 19
     5.7.  Jitter . . . . . . . . . . . . . . . . . . . . . . . . . . 20
     5.8.  Hop Limit Parameter  . . . . . . . . . . . . . . . . . . . 20
     5.9.  Willingness  . . . . . . . . . . . . . . . . . . . . . . . 21
     5.10. Parameter Change Constraints . . . . . . . . . . . . . . . 21
   6.  Local Information Base . . . . . . . . . . . . . . . . . . . . 22
     6.1.  Originator Set . . . . . . . . . . . . . . . . . . . . . . 23
     6.2.  Local Attached Network Set . . . . . . . . . . . . . . . . 23
   7.  Interface Information Base . . . . . . . . . . . . . . . . . . 24
   8.  Neighbor Information Base  . . . . . . . . . . . . . . . . . . 24
   9.  Topology Information Base  . . . . . . . . . . . . . . . . . . 25



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     9.1.  Advertising Remote Router Set  . . . . . . . . . . . . . . 25
     9.2.  Router Topology Set  . . . . . . . . . . . . . . . . . . . 26
     9.3.  Routable Address Topology Set  . . . . . . . . . . . . . . 26
     9.4.  Attached Network Set . . . . . . . . . . . . . . . . . . . 27
     9.5.  Routing Set  . . . . . . . . . . . . . . . . . . . . . . . 28
   10. Received Message Information Base  . . . . . . . . . . . . . . 28
     10.1. Received Set . . . . . . . . . . . . . . . . . . . . . . . 28
     10.2. Processed Set  . . . . . . . . . . . . . . . . . . . . . . 29
     10.3. Forwarded Set  . . . . . . . . . . . . . . . . . . . . . . 29
   11. Updating Information Bases . . . . . . . . . . . . . . . . . . 30
   12. Packets and Messages . . . . . . . . . . . . . . . . . . . . . 31
   13. Message Processing and Forwarding  . . . . . . . . . . . . . . 32
     13.1. Actions when Receiving a Message . . . . . . . . . . . . . 33
     13.2. Message Considered for Processing  . . . . . . . . . . . . 33
     13.3. Message Considered for Forwarding  . . . . . . . . . . . . 34
   14. HELLO messages . . . . . . . . . . . . . . . . . . . . . . . . 36
     14.1. HELLO Message Generation . . . . . . . . . . . . . . . . . 36
     14.2. HELLO Message TLVs . . . . . . . . . . . . . . . . . . . . 37
       14.2.1. Message TLVs . . . . . . . . . . . . . . . . . . . . . 37
       14.2.2. Address Block TLVs . . . . . . . . . . . . . . . . . . 38
     14.3. HELLO Message Transmission . . . . . . . . . . . . . . . . 38
     14.4. HELLO Message Processing . . . . . . . . . . . . . . . . . 38
       14.4.1. HELLO Message Discarding . . . . . . . . . . . . . . . 38
       14.4.2. HELLO Message Usage  . . . . . . . . . . . . . . . . . 39
   15. TC Messages  . . . . . . . . . . . . . . . . . . . . . . . . . 40
     15.1. TC Message Generation  . . . . . . . . . . . . . . . . . . 40
     15.2. TC Message TLVs  . . . . . . . . . . . . . . . . . . . . . 42
       15.2.1. Message TLVs . . . . . . . . . . . . . . . . . . . . . 42
       15.2.2. Address Block TLVs . . . . . . . . . . . . . . . . . . 42
     15.3. TC Message Transmission  . . . . . . . . . . . . . . . . . 43
     15.4. TC Message Processing  . . . . . . . . . . . . . . . . . . 44
       15.4.1. Invalid Message  . . . . . . . . . . . . . . . . . . . 45
       15.4.2. TC Message Processing Definitions  . . . . . . . . . . 46
       15.4.3. Initial TC Message Processing  . . . . . . . . . . . . 46
       15.4.4. Completing TC Message Processing . . . . . . . . . . . 49
   16. Information Base Changes . . . . . . . . . . . . . . . . . . . 50
     16.1. Originator Address Changes . . . . . . . . . . . . . . . . 50
     16.2. Neighbor State Changes . . . . . . . . . . . . . . . . . . 51
     16.3. Advertised Neighbor Changes  . . . . . . . . . . . . . . . 51
     16.4. Advertising Remote Router Tuple Expires  . . . . . . . . . 51
     16.5. Neighborhood Changes and MPR Updates . . . . . . . . . . . 52
     16.6. Routing Set Updates  . . . . . . . . . . . . . . . . . . . 53
   17. Selecting MPRs . . . . . . . . . . . . . . . . . . . . . . . . 54
   18. Routing Set Calculation  . . . . . . . . . . . . . . . . . . . 55
     18.1. Network Topology Graph . . . . . . . . . . . . . . . . . . 56
     18.2. Populating the Routing Set . . . . . . . . . . . . . . . . 58
   19. Proposed Values for Parameters and Constants . . . . . . . . . 59
     19.1. Local History Time Parameters  . . . . . . . . . . . . . . 59



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     19.2. Message Interval Parameters  . . . . . . . . . . . . . . . 59
     19.3. Advertised Information Validity Time Parameters  . . . . . 59
     19.4. Received Message Validity Time Parameters  . . . . . . . . 59
     19.5. Jitter Time Parameters . . . . . . . . . . . . . . . . . . 59
     19.6. Hop Limit Parameter  . . . . . . . . . . . . . . . . . . . 59
     19.7. Willingness Parameter and Constants  . . . . . . . . . . . 60
   20. Sequence Numbers . . . . . . . . . . . . . . . . . . . . . . . 60
   21. Extensions . . . . . . . . . . . . . . . . . . . . . . . . . . 60
   22. Security Considerations  . . . . . . . . . . . . . . . . . . . 61
     22.1. Confidentiality  . . . . . . . . . . . . . . . . . . . . . 61
     22.2. Integrity  . . . . . . . . . . . . . . . . . . . . . . . . 62
     22.3. Interaction with External Routing Domains  . . . . . . . . 63
   23. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 63
     23.1. Expert Review: Evaluation Guidelines . . . . . . . . . . . 64
     23.2. Message Types  . . . . . . . . . . . . . . . . . . . . . . 64
     23.3. Message-Type-specific TLV Type Registries  . . . . . . . . 64
     23.4. Message TLV Types  . . . . . . . . . . . . . . . . . . . . 65
     23.5. Address Block TLV Types  . . . . . . . . . . . . . . . . . 66
     23.6. NBR_ADDR_TYPE Values . . . . . . . . . . . . . . . . . . . 68
   24. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 68
   25. Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 68
   26. References . . . . . . . . . . . . . . . . . . . . . . . . . . 69
     26.1. Normative References . . . . . . . . . . . . . . . . . . . 69
     26.2. Informative References . . . . . . . . . . . . . . . . . . 69
   Appendix A.  Example Algorithm for Calculating MPRs  . . . . . . . 70
     A.1.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . 71
     A.2.  MPR Selection Algorithm for each OLSRv2 Interface  . . . . 71
   Appendix B.  Example Algorithm for Calculating the Routing Set . . 72
     B.1.  Local Interfaces and Neighbors . . . . . . . . . . . . . . 72
     B.2.  Add Neighbor Routers . . . . . . . . . . . . . . . . . . . 73
     B.3.  Add Remote Routers . . . . . . . . . . . . . . . . . . . . 73
     B.4.  Add Neighbor Addresses . . . . . . . . . . . . . . . . . . 74
     B.5.  Add Remote Routable Addresses  . . . . . . . . . . . . . . 74
     B.6.  Add Attached Networks  . . . . . . . . . . . . . . . . . . 75
     B.7.  Add 2-Hop Neighbors  . . . . . . . . . . . . . . . . . . . 76
   Appendix C.  TC Message Example  . . . . . . . . . . . . . . . . . 76
   Appendix D.  Constraints . . . . . . . . . . . . . . . . . . . . . 78
   Appendix E.  Flow and Congestion Control . . . . . . . . . . . . . 82













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1.  Introduction

   The Optimized Link State Routing protocol version 2 (OLSRv2) is an
   update to OLSR (version 1) as published in [RFC3626].  Compared to
   [RFC3626], OLSRv2 retains the same basic mechanisms and algorithms,
   while using a more flexible and efficient signaling framework, and
   includes some simplification of the messages being exchanged.

   OLSRv2 is developed for mobile ad hoc networks.  It operates as a
   table driven, proactive protocol, i.e., it exchanges topology
   information with other routers in the network regularly.  OLSRv2 is
   an optimization of the classical link state routing protocol.  Its
   key concept is that of MultiPoint Relays (MPRs).  Each router selects
   as MPRs a set of its neighbor routers that "cover" all of its
   symmetrically connected 2-hop neighbor routers.  MPRs are then used
   to achieve both flooding reduction and topology reduction.

   Flooding reduction is achieved by control traffic being flooded
   through the network using hop by hop forwarding, but with a router
   only needing to forward control traffic that is first received
   directly from one of the routers that have selected it as an MPR (its
   "MPR selectors").  This mechanism, denoted "MPR flooding", provides
   an efficient mechanism for information distribution within the MANET
   by reducing the number of transmissions required.

   Topology reduction is achieved by assigning a special responsibility
   to routers selected as MPRs when declaring link state information.  A
   sufficient requirement for OLSRv2 to provide shortest (lowest hop
   count) routes to all destinations is that routers declare link state
   information for their MPR selectors, if any.  Routers that are not
   selected as MPRs need not send any link state information.  Thus the
   use of MPRs allows reduction of the number and the size of link state
   messages, and in the amount of link state information maintained in
   each router.  Based on this reduced link state information, MPRs are
   used as intermediate routers in multi-hop routes.

   A router selects MPRs from among its one hop neighbors connected by
   "symmetric", i.e., bidirectional, links.  Therefore, selecting routes
   through MPRs avoids the problems associated with data packet transfer
   over unidirectional links (e.g., the problem of not getting link
   layer acknowledgments at each hop, for link layers employing this
   technique).

   OLSRv2 uses and extends [NHDP] and uses [RFC5444], [RFC5497] and,
   optionally, [RFC5148].  These other protocols and specifications were
   all originally created as part of OLSRv2, but have been specified
   separately for wider use.




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   OLSRv2 makes no assumptions about the underlying link layer.  OLSRv2,
   through its use of [NHDP], may use link layer information and
   notifications when available and applicable.

   OLSRv2, as OLSR [RFC3626], inherits its concept of forwarding and
   relaying from HIPERLAN (a MAC layer protocol) which is standardized
   by ETSI [HIPERLAN], [HIPERLAN2].

2.  Terminology

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

   All terms introduced in [RFC5444], including "packet", "Packet
   Header", "message", "Message Header", "Message Body", "Message Type",
   "message sequence number", "hop limit", "hop count", "Address Block",
   "TLV Block", "TLV", "Message TLV", "Address Block TLV", "type" (of
   TLV), "type extension" (of TLV), "value" (of TLV), "address",
   "address prefix", and "address object" are to be interpreted as
   described there.

   All terms introduced in [NHDP], including "interface", "MANET
   interface", "network address", "link", "symmetric link", "1-hop
   neighbor", "symmetric 1-hop neighbor", "symmetric 2-hop neighbor",
   "constant", "interface parameter", "router parameter", "Information
   Base", and "HELLO message" are to be interpreted as described there.

   Additionally, this document uses the following terminology:

   Router -  A MANET router which implements this protocol.

   OLSRv2 interface -  A MANET interface running this protocol.

   Routable address -   A network address which may be used as the
      destination of a packet.  A router MUST be able to distinguish a
      routable address from a non-routable address by direct inspection
      of the network address, based on global scope address allocations
      by IANA and/or administrative configuration.  Broadcast, multicast
      and anycast addresses, and addresses which are limited in scope to
      less than the entire MANET, MUST NOT be considered as routable
      addresses.

   Originator address -  An address which is unique (within the MANET)
      to a router.  A router MUST select an originator address; it MAY
      choose one of its interface addresses as its originator address.
      If it selects a routable address then this MUST be one which this



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      router will accept as destination.  An originator address MUST NOT
      have a prefix length, except for when included in an Address Block
      where it MAY be associated with a prefix of maximum prefix length
      (e.g., if the originator address is an IPv6 address, it MUST have
      either no prefix length, or have a prefix length of 128).  An
      originator address may be a routable or non-routable address.

   Message originator address -  The originator address of the router
      which created a message, as deduced from that message by its
      recipient.  The message originator address will usually be
      included in the message as its <msg-orig-addr> element as defined
      in [RFC5444].  However an exceptional case in a HELLO message is
      also allowed by this specification, when a router only uses a
      single address.  For all messages used in this specification,
      including HELLO messages defined in [NHDP], the recipient MUST be
      able to deduce an originator address.

   Willingness -  A numerical value between WILL_NEVER and WILL_ALWAYS
      (both inclusive), that represents the router's willingness to be
      selected as an MPR.

   Willing symmetric 1-hop neighbor -  A symmetric 1-hop neighbor of
      this router that has willingness not equal to WILL_NEVER.

   Symmetric 1-hop neighbor through OLSRv2 interface I -  A symmetric
      1-hop neighbor of the router via a symmetric link using OLSRv2
      interface I of the router.

   Willing symmetric 1-hop neighbor through OLSRv2 interface I -  A
      willing symmetric 1-hop neighbor of the router via a symmetric
      link using OLSRv2 interface I of the router.

   Symmetric strict 2-hop neighbor -  A symmetric 1-hop neighbor of a
      willing symmetric 1-hop neighbor that is not a symmetric 1-hop
      neighbor.

   Symmetric strict 2-hop neighbor through OLSRv2 interface I -  A
      symmetric 1-hop neighbor of a willing symmetric 1-hop neighbor
      through OLSRv2 interface I that is not a symmetric 1-hop neighbor
      through OLSRv2 interface I. The router MAY elect to use only
      information received over OLSRv2 interface I in making this
      determination.

   Multipoint relay (MPR) -  A router, X, is an MPR for a router, Y, if
      router Y has indicated its selection of router X as an MPR in a
      recent HELLO message.





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   MPR selector -  A router, Y, is an MPR selector of router X if router
      Y has selected router X as an MPR.

   MPR flooding -  The optimized MANET-wide information distribution
      mechanism, employed by this protocol, in which a message is
      relayed by only a reduced subset of the routers in the network.
      MPR flooding is the mechanism by which flooding reduction is
      achieved.

   This document employs the same notational conventions as in [RFC5444]
   and [NHDP].

3.  Applicability Statement

   This protocol:

   o  Is a proactive routing protocol for mobile ad hoc networks
      (MANETs) [RFC2501].

   o  Is designed to work in networks with a dynamic topology, and in
      which messages may be lost, such as due to collisions in wireless
      networks.

   o  Supports routers that each have one or more participating OLSRv2
      interfaces.  The set of a router's interfaces may change over
      time.  Each OLSRv2 interface may have one or more network
      addresses (which may have prefix lengths), and these may also be
      dynamically changing.

   o  Enables hop-by-hop routing, i.e., each router can use its local
      information provided by this protocol to route packets.

   o  Continuously maintains routes to all destinations in the network,
      i.e., routes are instantly available and data traffic is subject
      to no delays due to route discovery.  Consequently, no data
      traffic buffering is required.

   o  Supports routers that have non-OLSRv2 interfaces which may be
      local to a router or that can serve as gateways towards other
      networks.

   o  Is optimized for large and dense networks; the larger and more
      dense a network, the more optimization can be achieved by using
      MPRs, compared to the classic link state algorithm.

   o  Uses [RFC5444] as described in its "Intended Usage" appendix and
      by [RFC5498].




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   o  Allows "external" and "internal" extensibility as enabled by
      [RFC5444].

   o  Is designed to work in a completely distributed manner, and does
      not depend on any central entity.

4.  Protocol Overview and Functioning

   The objective of this protocol is for each router to, independently:

   o  Identify all destinations in the network.

   o  Identify a sufficient subset of links in the network, in order
      that shortest paths can be calculated to all available
      destinations.

   o  Provide a Routing Set, containing these shortest paths from this
      router to all destinations (routable addresses and local links).

4.1.  Overview

   These objectives are achieved, for each router, by:

   o  Using [NHDP] to identify symmetric 1-hop neighbors and symmetric
      2-hop neighbors.

   o  Independently selecting MPRs from among its symmetric 1-hop
      neighbors such that all symmetric 2-hop neighbors are reachable
      via at least one symmetric 1-hop neighbor.  An analysis and
      examples of MPR selection algorithms is given in [MPR], a
      suggested algorithm is included in this specification.  Note that
      it is not necessary for routers to use the same algorithm in order
      to interoperate in the same MANET.

   o  Signaling its MPR selection by extending [NHDP] to include this
      information in outgoing HELLO messages, by the addition of MPR
      Address Block TLV(s) associated with the appropriate network
      addresses.

   o  Extracting its MPR selectors from received HELLO messages, using
      the included MPR Address Block TLV(s).

   o  Reporting its willingness to be an MPR in HELLO messages, by the
      addition on an MPR_WILLING Message TLV.  The router's willingness
      to be an MPR indicates how willing it is to participate in MPR
      flooding and to be an intermediate node for routing.  A node can
      absolutely decline to perform either role, while still being able
      to be a routing source or destination.



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   o  Using the message format specified in [RFC5444], specifically
      defining a TC (Topology Control) Message Type, used to
      periodically signal links between MPR selectors and itself
      throughout the MANET.

   o  Allowing its TC messages, as well as HELLO messages, to be
      included in packets specified in [RFC5444], using the "manet" IP
      protocol or UDP port as specified in [RFC5498].

   o  Diffusing TC messages by using a flooding reduction mechanism,
      denoted "MPR flooding"; only the MPRs of a router will retransmit
      messages received from (i.e., originated or last relayed by) that
      router.

   Note that the indicated extensions to [NHDP] are of forms permitted
   by that specification.

   This specification defines:

   o  Parameters and constants used by this protocol, in addition to
      those specified in [NHDP].  Parameters used by this protocol may,
      where appropriate, be specific to a given OLSRv2 interface, or to
      a router.  This protocol allows all parameters to be changed
      dynamically, and to be set independently for each router or each
      OLSRv2 interface, as appropriate.

   o  Extensions to the Information Bases specified in [NHDP].

   o  Two new Information Bases: the Topology Information Base and the
      Received Message Information Base.

   o  A requirement for each router to have an originator address to be
      included in, or deducible from, the HELLO messages of [NHDP].

   o  A Message TLV, to be included in the HELLO messages of [NHDP],
      allowing a router to indicate its willingness to be an MPR.

   o  An Address Block TLV, to be included in the HELLO messages of
      [NHDP], allowing a router to signal its MPR selection.

   o  The MPR flooding mechanism, including the inclusion of message
      originator address and sequence number to manage duplicate
      messages.

   o  TC messages, which are used for MANET wide signaling (using MPR
      flooding) of selected topology (link state) information.





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   o  The specification of new Message TLVs and Address Block TLVs that
      are used in TC messages.

   o  The generation of TC messages from the appropriate information in
      the Information Bases.

   o  The updating of the Topology Information Base according to
      received TC messages.

   o  The response to other events, such as the expiration of
      information in the Information Bases.

   This 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.

   This protocol only interacts with IP through routing table
   management, and the use of the sending IP address for IP datagrams
   containing OLSRv2 packets.

4.2.  Routers and Interfaces

   In order for a router to participate in a MANET, it MUST have at
   least one, and possibly more, OLSRv2 interfaces.  Each OLSRv2
   interface:

   o  Is configured with one or more network addresses, as specified in
      [NHDP].  These addresses MUST each be specific to this router, and
      MUST include any address that will be used as the sending address
      of any IP packet sent on this OLSRv2 interface.

   o  Has a number of interface parameters, adding to those specified in
      [NHDP].

   o  Has an Interface Information Base, extending that specified in
      [NHDP].

   o  Generates and processes HELLO messages according to [NHDP],
      extended as specified in Section 14.

   In addition to a set of OLSRv2 interfaces as described above, each
   router:

   o  May have one or more non-OLSRv2 interfaces and/or local attached
      networks for which this router can accept packets.  All routable
      addresses for which the router is to accept packets MUST be used
      as an (OLSRv2 or non-OLSRv2) interface network address or as an
      address of a local attached network of the router.



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   o  Has a number of router parameters, adding to those specified in
      [NHDP].

   o  Has a Local Information Base, extending that specified in [NHDP],
      including selection of an originator address and recording any
      locally attached networks.

   o  Has a Neighbor Information Base, extending that specified in
      [NHDP] to record MPR selection and advertisement information.

   o  Has a Topology Information Base, recording information received in
      TC messages.

   o  Has a Received Message Information Base, recording information
      about received messages to ensure that each TC message is only
      processed once, and forwarded at most once on each OLSRv2
      interface, by a router.

   o  Generates and processes TC messages.

4.3.  Information Base Overview

   Each router maintains the Information Bases described in the
   following sections.  These are used for describing the protocol in
   this document.  An implementation of this protocol MAY maintain this
   information in the indicated form, or in any other organization which
   offers access to this information.  In particular, note that it is
   not necessary to remove Tuples from Sets at the exact time indicated,
   only to behave as if the Tuples were removed at that time.

4.3.1.  Local Information Base

   The Local Information Base is specified in [NHDP], and contains a
   router's local configuration.  It is extended in this specification
   to also record an originator address, and to include a router's:

   o  Originator Set, containing addresses that were recently used as
      this router's originator address, and is used, together with the
      router's current originator address, to enable a router to
      recognize and discard control traffic which was originated by the
      router itself.

   o  Local Attached Network Set, containing network addresses of
      networks to which this router can act as a gateway, and advertises
      in its TC messages.






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4.3.2.  Interface Information Bases

   The Interface Information Bases, one for each OLSRv2 interface, are
   specified in [NHDP].  In addition to the uses in [NHDP], information
   recorded in the Interface Information Bases is used for completing
   the Routing Set.

4.3.3.  Neighbor Information Base

   The Neighbor Information Base is specified in [NHDP], and is extended
   to also record each neighbor's originator address, the willingness of
   each neighbor to be an MPR, as well as this router's MPR
   relationships with each neighbor (whether an MPR and/or an MPR
   selector of that neighbor), and whether that neighbor is to be
   advertised in TC messages.

   A router selects some of its symmetric 1-hop neighbors as MPRs (see
   Section 17).  That selection is recorded in the Neighbor Set. This
   selection is then reported in the router's HELLO messages, extending
   the specification in [NHDP], by using an MPR Address Block TLV.  In
   making that selection, a router MUST consider its 1-hop neighbors'
   willingness to be an MPR, which (unless having default value) is
   reported using an Address Block TLV in HELLO messages and recorded in
   the receiving router's Neighbor Set.

   A router also records, in the Neighbor Set, which symmetric 1-hop
   neighbors have selected it as an MPR (i.e., its MPR selectors).  This
   is determined from the MPR TLVs in received HELLO messages.  It also
   records which symmetric 1-hop neighbors that it is to advertise
   connectivity to in its TC messages; this MUST include all of its MPR
   selectors.

   The Neighbor Set finally records each 1-hop neighbor's originator
   address, as deduced from received HELLO messages as described in
   Section 14.4.  This, and other information in the Neighbor Set,
   including each 1-hop neighbor's routable addresses, is used in
   advertising the selected symmetric 1-hop neighbors in TC messages.

4.3.4.  Topology Information Base

   The Topology Information Base in each router contains:

   o  An Advertising Remote Router Set, recording each other router from
      which TC messages have been received.  This is used in order to
      determine if a received TC message contains fresh or outdated
      information; a received TC message is ignored in the latter case.





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   o  A Router Topology Set, recording links between routers in the
      MANET, as described by received TC messages.

   o  A Routable Address Topology Set, recording routable addresses in
      the MANET (available as packet destinations) and from which other
      router these routable addresses can be directly reached (i.e., in
      a single IP hop), as reported by received TC messages.

   o  An Attached Network Set, recording networks to which a remote
      router has advertised that it may act as a gateway.  These
      networks may be reached in one or more IP hops.

   o  A Routing Set, recording routes from this router to all available
      destinations.  The IP routing table is to be updated using this
      Routing Set. (A router MAY choose to use any or all destination
      network addresses in the Routing Set to update the IP routing
      table, this selection is outside the scope of this protocol.)

   The purpose of the Topology Information Base is to record information
   used, in addition to that in the Local Information Base, the
   Interface Information Bases and the Neighbor Information Base, to
   construct the Routing Set (which is also included in the Topology
   Information Base).

   This specification describes the calculation of the Routing Set based
   on a Topology Graph constructed in two phases.  First, a "backbone"
   graph representing the routers in the MANET, and the connectivity
   between them, is constructed from the Local Information Base, the
   Neighbor Information Base and the Router Topology Set. Second, this
   graph is "decorated" with additional destination network addresses
   using the Local Information Base, the Routable Address Topology Set
   and the Attached Network Set.

   The Topology Graph does not need to be recorded in the Topology
   Information Base, it can either be constructed as required when the
   Routing Set is to be changed, or need not be explicitly constructed
   (as illustrated in Appendix B).  An implementation MAY construct and
   retain the Topology Graph if preferred.

4.3.5.  Received Message Information Base

   The Received Message Information Base in each router contains:

   o  A Received Set for each OLSRv2 interface, describing TC messages
      received by this router on that OLSRv2 interface.

   o  A Processed Set, describing TC messages processed by this router.




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   o  A Forwarded Set, describing TC messages forwarded by this router.

   The Received Message Information Base serves the MPR flooding
   mechanism by ensuring that received messages are forwarded at most
   once by a router, and also ensures that received messages are
   processed exactly once by a router.

4.4.  Signaling Overview

   This protocol generates and processes HELLO messages according to
   [NHDP], extended according to Section 14 of this specification to
   include an originator address and MPR selection information.

   This protocol specifies a single message type, the TC message.  TC
   messages are sent by their originating router proactively, at a
   regular interval.  This interval may be fixed, or may be dynamic, for
   example it may be backed off due to congestion or network stability.
   TC messages may also be sent as a response to a change in the router
   itself, or its advertised 1-hop neighborhood, for example on first
   being selected as an MPR.

   Because TC messages are sent periodically, this protocol is tolerant
   of unreliable transmissions of TC messages.  Message losses may occur
   more frequently in wireless networks due to collisions or other
   transmission problems.  This protocol MAY use "jitter", randomized
   adjustments to message transmission times, to reduce the incidence of
   collisions, as specified in [RFC5148].

   This protocol is tolerant of out of sequence delivery of TC messages
   due to in transit message reordering.  Each router maintains an
   Advertised Neighbor Sequence Number (ANSN) that is incremented when
   its recorded neighbor information that is to be included in its TC
   messages changes.  This ANSN is included in the router's TC messages.
   The recipient of a TC message can used this included ANSN to identify
   which of the information it has received is most recent, even if
   messages have been reordered while in transit.  Only the most recent
   information received is used, older information received later is
   discarded.

   TC messages may be "complete" or "incomplete".  A complete TC message
   advertises all of the originating router's MPR selectors, it may also
   advertise other symmetric 1-hop neighbors.  Complete TC messages are
   generated periodically (and also, optionally, in response to
   neighborhood changes).  Incomplete TC messages may be used to report
   additions to advertised information, without repeating unchanged
   information.

   TC messages, and HELLO messages as extended by this specification,



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   include an originator address for the router that created the
   message.  A TC message reports both the originator addresses and
   routable addresses of its advertised neighbors, distinguishing the
   two using an Address Block TLV (an address may be both routable and
   an originator address).  TC messages also report the originator's
   locally attached networks.

   TC messages are MPR flooded throughout the MANET.  A router
   retransmits a TC message only if it is received from (i.e.,
   originated from or was last relayed by) one of that router's MPR
   selectors.

   Some TC messages may be MPR flooded over only part of the network,
   e.g., allowing a router to ensure that nearer routers are kept more
   up to date than distant routers, such as is used in Fisheye State
   Routing [FSR] and Fuzzy Sighted Link State routing [FSLS].  This is
   enabled using [RFC5497].

4.5.  Routing Set

   The purpose of the Routing Set is to determine and record routes
   (local interface network address and next hop interface network
   address) to all possible routable addresses advertised by this
   protocol, as well as of all destinations that are local, i.e., within
   one hop, to the router (whether using routable addresses or not).
   Only symmetric links are used in such routes.

   It is intended that the Routing Set can be used for packet routing,
   by using its contents to update IP's routing tables.  That update,
   and whether any Routing Tuples are not used in IP's routing table, is
   outside the scope of this specification.

   The signaling in this specification has been designed so that a
   "backbone" Topology Graph of routers, each identified by its
   originator address, with at most one direct connection between any
   pair of routers, can be constructed (from the Neighbor Set and the
   Router Topology Set) using a suitable minimum path length algorithm.
   This Topology Graph can, then, have other network addresses (routable
   or of symmetric 1-hop neighbors) added to it (using the Interface
   Information Bases, the Routable Address Topology Set and the Attached
   Network Set).

5.  Protocol Parameters and Constants

   The parameters and constants used in this specification are those
   defined in [NHDP] plus those defined in this section.  The separation
   in [NHDP] into interface parameters, router parameters and constants
   is also used in this specification, however all but one



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   (RX_HOLD_TIME) of the parameters added by this specification are
   router parameters.

   Parameters and constants are detailed in the following sections.  As
   for the parameters in [NHDP], parameters defined in this
   specification may be changed dynamically by a router, and need not be
   the same on different routers, even in the same MANET, or, for
   interface parameters, on different interfaces of the same router.

5.1.  Protocol and Port Numbers

   This protocol specifies TC messages, which are included in packets as
   defined by [RFC5444].  These packets may be sent either using the
   "manet" protocol number or the "manet" UDP well-known port number, as
   specified in [RFC5498].

   TC messages and HELLO messages [NHDP] SHOULD, in a given deployment
   of this protocol, both be using the same of either of IP or UDP, in
   order that it is possible to combine messages of both protocols into
   the same [RFC5444] packet for transmission.

5.2.  Multicast Address

   This protocol specifies TC messages, which are included in packets as
   defined by [RFC5444].  These packets MAY be transmitted using the
   link local multicast address "LL-MANET-Routers", as specified in
   [RFC5498].

5.3.  Local History Times

   The following router parameter manages the time for which local
   information is retained:

   O_HOLD_TIME  - is used to define the time for which a recently used
      and replaced originator address is used to recognize the router's
      own messages.

   The following constraint applies to this parameter:

   o  O_HOLD_TIME >= 0

5.4.  Message Intervals

   The following router parameters regulate TC message transmissions by
   a router.  TC messages are usually sent periodically, but MAY also be
   sent in response to changes in the router's Neighbor Set and/or Local
   Attached Network Set. In a highly dynamic network, and with a larger
   value of the parameter TC_INTERVAL and a smaller value of the



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   parameter TC_MIN_INTERVAL, TC messages may be transmitted more often
   in response to changes than periodically.  However because a router
   has no knowledge of, for example, routers remote to it (i.e., beyond
   two hops away) joining the network, TC messages MUST NOT be sent
   purely responsively.

   TC_INTERVAL  - is the maximum time between the transmission of two
      successive TC messages by this router.  When no TC messages are
      sent in response to local network changes (by design, or because
      the local network is not changing) then TC messages SHOULD be sent
      at a regular interval TC_INTERVAL, possibly modified by jitter as
      specified in [RFC5148].

   TC_MIN_INTERVAL  - is the minimum interval between transmission of
      two successive TC messages by this router.  (This minimum interval
      MAY be modified by jitter, as specified in [RFC5148].)

   The following constraints apply to these parameters:

   o  TC_INTERVAL > 0

   o  TC_MIN_INTERVAL >= 0

   o  TC_INTERVAL >= TC_MIN_INTERVAL

   o  If TLVs with Type = INTERVAL_TIME, as defined in [RFC5497], are
      included in TC messages, then TC_INTERVAL MUST be representable as
      described in [RFC5497].

5.5.  Advertised Information Validity Times

   The following router parameters manage the validity time of
   information advertised in TC messages:

   T_HOLD_TIME  - is used to define the minimum value in the TLV with
      Type = VALIDITY_TIME included in all TC messages sent by this
      router.  If a single value of parameter TC_HOP_LIMIT (see
      Section 5.8) is used then this will be the only value in that TLV.

   A_HOLD_TIME  - is the period during which TC messages are sent after
      they no longer have any advertised information to report, but are
      sent in order to accelerate outdated information removal by other
      routers.

   The following constraints apply to these parameters:






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   o  T_HOLD_TIME > 0

   o  A_HOLD_TIME >= 0

   o  T_HOLD_TIME >= TC_INTERVAL

   o  If TC messages can be lost, then both T_HOLD_TIME and A_HOLD_TIME
      SHOULD be significantly greater than TC_INTERVAL; a value >= 3 x
      TC_INTERVAL is RECOMMENDED.

   o  T_HOLD_TIME MUST be representable as described in [RFC5497].

5.6.  Received Message Validity Times

   The following parameters manage the validity time of recorded
   received message information:

   RX_HOLD_TIME  - is an interface parameter, and is the period after
      receipt of a message by the appropriate OLSRv2 interface of this
      router for which that information is recorded, in order that the
      message is recognized as having been previously received on this
      OLSRv2 interface.

   P_HOLD_TIME  - is a router parameter, and is the period after receipt
      of a message that is processed by this router for which that
      information is recorded, in order that the message is not
      processed again if received again.

   F_HOLD_TIME  - is a router parameter, and is the period after receipt
      of a message that is forwarded by this router for which that
      information is recorded, in order that the message is not
      forwarded again if received again.

   The following constraints apply to these parameters:

   o  RX_HOLD_TIME > 0

   o  P_HOLD_TIME > 0

   o  F_HOLD_TIME > 0

   o  All of these parameters SHOULD be greater than the maximum
      difference in time that a message may take to traverse the MANET,
      taking into account any message forwarding jitter as well as
      propagation, queuing, and processing delays.






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5.7.  Jitter

   If jitter, as defined in [RFC5148], is used then the governing jitter
   parameters are as follows:

   TP_MAXJITTER  - represents the value of MAXJITTER used in [RFC5148]
      for periodically generated TC messages sent by this router.

   TT_MAXJITTER  - represents the value of MAXJITTER used in [RFC5148]
      for externally triggered TC messages sent by this router.

   F_MAXJITTER  - represents the default value of MAXJITTER used in
      [RFC5148] for messages forwarded by this router.  However before
      using F_MAXJITTER a router MAY attempt to deduce a more
      appropriate value of MAXJITTER, for example based on any TLVs with
      Type = INTERVAL_TIME or Type = VALIDITY_TIME contained in the
      message to be forwarded.

   For constraints on these parameters see [RFC5148].

5.8.  Hop Limit Parameter

   The parameter TC_HOP_LIMIT is the hop limit set in each TC message.
   TC_HOP_LIMIT MAY be a single fixed value, or MAY be different in TC
   messages sent by the same router.  However each other router, at any
   hop count distance, SHOULD see a regular pattern of TC messages in
   order that meaningful values of TLVs with Type = INTERVAL_TIME and
   Type = VALIDITY_TIME at each hop count distance can be included as
   defined in [RFC5497].  Thus the pattern of TC_HOP_LIMIT SHOULD be
   defined to have this property.  For example the repeating pattern
   (255 4 4) satisfies this property (having period TC_INTERVAL at hop
   counts up to 4, inclusive, and 3 x TC_INTERVAL at hop counts greater
   than 4), but the repeating pattern (255 255 4 4) does not satisfy
   this property because at hop counts greater than 4, message intervals
   are alternately TC_INTERVAL and 3 x TC_INTERVAL.

   The following constraints apply to this parameter:

   o  The maximum value of TC_HOP_LIMIT >= the network diameter in hops,
      a value of 255 is RECOMMENDED.  Note that if using a pattern of
      different values of TC_HOP_LIMIT as described above, then only the
      maximum value in the pattern is so constrained.

   o  All values of TC_HOP_LIMIT >= 2.







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5.9.  Willingness

   Each router has a WILLINGNESS parameter, which MUST be in the range
   WILL_NEVER to WILL_ALWAYS, inclusive, and which represents the
   router's willingness to be an MPR, and hence its willingness to
   forward messages and be an intermediate router on routes.  The higher
   the value, the greater the router's willingness to be an MPR.  If a
   router has WILLINGNESS = WILL_NEVER (the lowest possible value) it
   does not perform these tasks.  A MANET using this protocol with too
   many routers having WILLINGNESS = WILL_NEVER will not function; it
   MUST be ensured, by administrative or other means, that this does not
   happen.  If a router has WILLINGNESS = WILL_ALWAYS (the highest
   possible value) then it MUST always be selected as an MPR by all
   symmetric 1-hop neighbors.

   Routers MAY have different WILLINGNESS values; however the three
   constants WILL_NEVER, WILL_DEFAULT and WILL_ALWAYS MUST have the
   values defined in Section 19.  (Use of WILLINGNESS = WILL_DEFAULT
   allows a router to avoid advertising its WILLINGNESS in its HELLO
   messages.)

   The following constraints apply to this parameter:

   o  WILLINGNESS >= WILL_NEVER

   o  WILLINGNESS <= WILL_ALWAYS

5.10.  Parameter Change Constraints

   If protocol parameters are changed dynamically, then the constraints
   in this section apply.

   O_HOLD_TIME

      *  If O_HOLD_TIME for a router changes, then the expiry time for
         all Originator Tuples MAY be changed.

   TC_INTERVAL

      *  If the TC_INTERVAL for a router increases, then the next TC
         message generated by this router MUST be generated according to
         the previous, shorter, TC_INTERVAL.  Additional subsequent TC
         messages MAY be generated according to the previous, shorter,
         TC_INTERVAL.

      *  If the TC_INTERVAL for a router decreases, then the following
         TC messages from this router MUST be generated according to the
         current, shorter, TC_INTERVAL.



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   RX_HOLD_TIME

      *  If RX_HOLD_TIME for an OLSRv2 interface changes, then the
         expiry time for all Received Tuples for that OLSRv2 interface
         MAY be changed.

   P_HOLD_TIME

      *  If P_HOLD_TIME changes, then the expiry time for all Processed
         Tuples MAY be changed.

   F_HOLD_TIME

      *  If F_HOLD_TIME changes, then the expiry time for all Forwarded
         Tuples MAY be changed.

   TP_MAXJITTER

      *  If TP_MAXJITTER changes, then the periodic TC message schedule
         on this router MAY be changed immediately.

   TT_MAXJITTER

      *  If TT_MAXJITTER changes, then externally triggered TC messages
         on this router MAY be rescheduled.

   F_MAXJITTER

      *  If F_MAXJITTER changes, then TC messages waiting to be
         forwarded with a delay based on this parameter MAY be
         rescheduled.

   TC_HOP_LIMIT

      *  If TC_HOP_LIMIT changes, and the router uses multiple values
         after the change, then message intervals and validity times
         included in TC messages MUST be respected.  The simplest way to
         do this is to start any new repeating pattern of TC_HOP_LIMIT
         values with its largest value.

6.  Local Information Base

   The Local Information Base, as defined for each router in [NHDP], is
   extended by this protocol by:

   o  Recording the router's originator address.  The originator address
      MUST be unique to this router.  It MUST NOT be used by any other
      router as an originator address.  It MAY be included in any



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      network address in any I_local_iface_addr_list of this router, it
      MUST NOT be included in any network address in any
      I_local_iface_addr_list of any other router.  It MAY be included
      in, but MUST NOT be equal to, the AL_net_addr in any Local
      Attached Network Tuple in this or any other router.

   o  The addition of an Originator Set, defined in Section 6.1, and a
      Local Attached Network Set, defined in Section 6.2.

   All routable addresses of the router for which it is to accept
   packets as destination MUST be included in the Local Interface Set or
   the Local Attached Network Set.

6.1.  Originator Set

   A router's Originator Set records addresses that were recently used
   as originator addresses by this router.  If a router's originator
   address is immutable then this set is always empty and MAY be
   omitted.  It consists of Originator Tuples:

      (O_orig_addr, O_time)

   where:

   O_orig_addr -  is a recently used originator address, note that this
      does not include a prefix length;

   O_time -  specifies the time at which this Tuple expires and MUST be
      removed.

6.2.  Local Attached Network Set

   A router's Local Attached Network Set records its local non-OLSRv2
   interfaces via which it can act as gateways to other networks.  The
   Local Attached Network Set is not modified by this protocol.  This
   protocol MAY respond to changes to the Local Attached Network Set,
   which MUST reflect corresponding changes in the router's status.  It
   consists of Local Attached Network Tuples:

      (AL_net_addr, AL_dist)

   where:

   AL_net_addr -  is the network address of an attached network which
      can be reached via this router.  This SHOULD be a routable
      address.  It is constrained as described below.





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   AL_dist -  is the number of hops to the network with network address
      AL_net_addr from this router.

   Attached networks local to this router only (i.e., not reachable
   except via this router) SHOULD be treated as local non-MANET
   interfaces, and added to the Local Interface Set, as specified in
   [NHDP], rather than be added to the Local Attached Network Set.

   Because an attached network is not specific to the router, and may be
   outside the MANET, an attached network MAY also be attached to other
   routers.  Routing to an AL_net_addr will use maximum prefix length
   matching; consequently an AL_net_addr MAY include, but MUST NOT equal
   or be included in, any network address which is of any interface of
   any router (i.e., is included in any I_local_iface_addr_list) or
   equal any router's originator address.

   It is not the responsibility of this protocol to maintain routes from
   this router to networks recorded in the Local Attached Network Set.

   Local Attached Neighbor Tuples are removed from the Local Attached
   Network Set only when the routers' local attached network
   configuration changes, i.e., they are not subject to timer-based
   expiration or changes due to received messages.

7.  Interface Information Base

   An Interface Information Base, as defined in [NHDP], is maintained
   for each OLSRv2 interface.  It is not modified by this protocol.

8.  Neighbor Information Base

   An Neighbor Information Base, as defined in [NHDP], is maintained for
   each router.  It is modified by this protocol by adding these
   additional elements to each Neighbor Tuple in the Neighbor Set:

   N_orig_addr -  is the neighbor's originator address, which may be
      unknown.  Note that this originator address does not include a
      prefix length;

   N_willingness -  is the neighbor's willingness to be selected as an
      MPR, in the range from WILL_NEVER to WILL_ALWAYS, both inclusive;

   N_mpr -  is a boolean flag, describing if this neighbor is selected
      as an MPR by this router;







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   N_mpr_selector -  is a boolean flag, describing if this neighbor has
      selected this router as an MPR, i.e., is an MPR selector of this
      router.

   N_advertised -  is a boolean flag, describing if this router has
      elected to advertise a link to this neighbor in its TC messages.

   A Neighbor Tuple created (but not updated) by [NHDP] MUST set:

      N_orig_addr := unknown;

      N_willingness := WILL_NEVER;

      N_mpr := false;

      N_mpr_selector := false;

      N_advertised := false.

   The Neighbor Information Base also includes a variable, the
   Advertised Neighbor Sequence Number (ANSN), whose value is included
   in TC messages to indicate the freshness of the information
   transmitted.  The ANSN is incremented whenever advertised information
   (the originator and routable addresses included in Neighbor Tuples
   with N_advertised = true, and local attached networks recorded in the
   Local Attached Network Set in the Local Information Base) changes,
   including addition or removal of such information.

9.  Topology Information Base

   The Topology Information Base, defined for each router by this
   specification, stores information received in TC messages, in the
   Advertising Remote Router Set, the Router Topology Set, the Routable
   Address Topology Set and the Attached Network Set.

   Additionally, a Routing Set is maintained, derived from the
   information recorded in the Local Information Base, the Interface
   Information Bases, the Neighbor Information Base and the rest of the
   Topology Information Base.

9.1.  Advertising Remote Router Set

   A router's Advertising Remote Router Set records information
   describing each remote router in the network that transmits TC
   messages, allowing outdated TC messages to be recognized and
   discarded.  It consists of Advertising Remote Router Tuples:

      (AR_orig_addr, AR_seq_number, AR_time)



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   where:

   AR_orig_addr -  is the originator address of a received TC message,
      note that this does not include a prefix length;

   AR_seq_number -  is the greatest ANSN in any TC message received
      which originated from the router with originator address
      AR_orig_addr (i.e., which contributed to the information contained
      in this Tuple);

   AR_time -  is the time at which this Tuple expires and MUST be
      removed.

9.2.  Router Topology Set

   A router's Topology Set records topology information about the links
   between routers in the MANET.  It consists of Router Topology Tuples:

      (TR_from_orig_addr, TR_to_orig_addr, TR_seq_number, TR_time)

   where:

   TR_from_orig_addr -  is the originator address of a router which can
      reach the router with originator address TR_to_orig_addr in one
      hop, note that this does not include a prefix length;

   TR_to_orig_addr -  is the originator address of a router which can be
      reached by the router with originator address TR_to_orig_addr in
      one hop, note that this does not include a prefix length;

   TR_seq_number -  is the greatest ANSN in any TC message received
      which originated from the router with originator address
      TR_from_orig_addr (i.e., which contributed to the information
      contained in this Tuple);

   TR_time -  specifies the time at which this Tuple expires and MUST be
      removed.

9.3.  Routable Address Topology Set

   A router's Routable Address Topology Set records topology information
   about the routable addresses within the MANET, and via which routers
   they may be reached.  It consists of Routable Address Topology
   Tuples:

      (TA_from_orig_addr, TA_dest_addr, TA_seq_number, TA_time)

   where:



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   TA_from_orig_addr -  is the originator address of a router which can
      reach the router with routable address TA_dest_addr in one hop,
      note that this does not include a prefix length;

   TA_dest_addr -  is a routable address of a router which can be
      reached by the router with originator address TA_from_orig_addr in
      one hop;

   TA_seq_number -  is the greatest ANSN in any TC message received
      which originated from the router with originator address
      TA_from_orig_addr (i.e., which contributed to the information
      contained in this Tuple);

   TA_time -  specifies the time at which this Tuple expires and MUST be
      removed.

9.4.  Attached Network Set

   A router's Attached Network Set records information about networks
   (which may be outside the MANET) attached to other routers and their
   routable addresses.  It consists of Attached Network Tuples:

      (AN_orig_addr, AN_net_addr, AN_dist, AN_seq_number, AN_time)

   where:

   AN_orig_addr -  is the originator address of a router which can act
      as gateway to the network with network address AN_net_addr, note
      that this does not include a prefix length;

   AN_net_addr -  is the network address of an attached network, which
      may be reached via the router with originator address
      AN_orig_addr;

   AN_dist -  is the number of hops to the network with network address
      AN_net_addr from the router with originator address AN_orig_addr;

   AN_seq_number -  is the greatest ANSN in any TC message received
      which originated from the router with originator address
      AN_orig_addr (i.e., which contributed to the information contained
      in this Tuple);

   AN_time -  specifies the time at which this Tuple expires and MUST be
      removed.







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9.5.  Routing Set

   A router's Routing Set records the first hop along a selected path to
   each destination for which any such path is known.  It consists of
   Routing Tuples:

      (R_dest_addr, R_next_iface_addr, R_local_iface_addr, R_dist)

   where:

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

   R_next_iface_addr -  is the network address of the "next hop" on the
      selected path to the destination;

   R_local_iface_addr -  is the network address of the local OLSRv2
      interface over which a packet MUST be sent to reach the
      destination by the selected path.

   R_dist -  is the number of hops on the selected path to the
      destination;

   The Routing Set for a router is derived from the contents of other
   protocol Sets of the router (the Link Sets, the Neighbor Set, the
   Router Topology Set, the Routable Address Topology Set, the Attached
   Network Set, and OPTIONALLY the Two Hop Sets).  The Routing Set is
   updated (Routing Tuples added or removed, or the complete Routing Set
   recalculated) when routing paths are calculated, based on changes to
   these other protocol Sets.  Routing Tuples are not subject to timer-
   based expiration.

10.  Received Message Information Base

   The Received Message Information Base, defined by this specification,
   records information required to ensure that a message is processed at
   most once and is forwarded at most once per OLSRv2 interface of a
   router, using MPR flooding.

10.1.  Received Set

   A router has a Received Set per OLSRv2 interface.  Each Received Set
   records the signatures of messages which have been received over that
   OLSRv2 interface.  Each consists of Received Tuples:

      (RX_type, RX_orig_addr, RX_seq_number, RX_time)




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   where:

   RX_type -  is the received Message Type;

   RX_orig_addr -  is the originator address of the received message,
      note that this does not include a prefix length;

   RX_seq_number -  is the message sequence number of the received
      message;

   RX_time -  specifies the time at which this Tuple expires and MUST be
      removed.

10.2.  Processed Set

   A router has a single Processed Set which records signatures of
   messages which have been processed by the router.  It consists of
   Processed Tuples:

      (P_type, P_orig_addr, P_seq_number, P_time)

   where:

   P_type -  is the processed Message Type;

   P_orig_addr -  is the originator address of the processed message,
      note that this does not include a prefix length;

   P_seq_number -  is the message sequence number of the processed
      message;

   P_time -  specifies the time at which this Tuple expires and MUST be
      removed.

10.3.  Forwarded Set

   A router has a single Forwarded Set which records signatures of
   messages which have been forwarded by the router.  It consists of
   Forwarded Tuples:

      (F_type, F_orig_addr, F_seq_number, F_time)

   where:

   F_type -  is the forwarded Message Type;






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   F_orig_addr -  is the originator address of the forwarded message,
      note that this does not include a prefix length;

   F_seq_number -  is the message sequence number of the forwarded
      message;

   F_time -  specifies the time at which this Tuple expires and MUST be
      removed.

11.  Updating Information Bases

   The purpose of this protocol is to determine the contents of the
   router's Routing Set, which may be used to update IP's Routing Table,
   providing "next hop" routing information for IP packets.  This is
   performed by first updating the other Protocol Sets in the
   Information Bases, and then using information from some of those
   other Protocol Sets to determine the contents of the Routing Set.

   As part of this specification, in a number of cases there is a
   natural correspondence from a Protocol Tuple in one Protocol Set to a
   single Protocol Tuple in another Protocol Set, in the same or another
   Information Base.  The latter Protocol Tuple is referred to as
   "corresponding" to the former Protocol Tuple.

   Specific examples of corresponding Protocol Tuples include:

   o  There is a Local Interface Tuple corresponding to each Link Tuple,
      where the Link Tuple is in the Link Set for an OLSRv2 interface,
      and the Local Interface Tuple represents that OLSRv2 interface.

   o  There is a Neighbor Tuple corresponding to each Link Tuple which
      has L_HEARD_time not expired, such that N_neighbor_addr_list
      contains L_neighbor_iface_addr_list.

   o  There is a Link Tuple (in the Link Set in the same Interface
      Information Base) corresponding to each 2-Hop Tuple such that
      L_neighbor_iface_addr_list = N2_neighbor_iface_addr_list.

   o  There is a Neighbor Tuple corresponding to each 2-Hop Tuple, such
      that N_neighbor_addr_list contains N2_neighbor_iface_addr_list.
      (This is the Neighbor Tuple corresponding to the Link Tuple that
      corresponds to the 2-Hop Tuple.)

   o  There is an Advertising Remote Router Tuple corresponding to each
      Router Topology Tuple such that AR_orig_addr = TR_from_orig_addr.

   o  There is an Advertising Remote Router Tuple corresponding to each
      Routable Address Topology Tuple such that AR_orig_addr =



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      TA_from_orig_addr.

   o  There is an Advertising Remote Router Tuple corresponding to each
      Attached Network Tuple such that AR_orig_addr = AN_orig_addr.

   o  There is an Neighbor Tuple corresponding to each Routing Tuple
      such that N_neighbor_addr_list contains R_next_iface_addr.

   Addresses or network addresses with the following properties are
   considered as "fully owned" by a router when processing a received
   message:

   o  Equaling its originator address, OR;

   o  Equaling the O_orig_addr in an Originator Tuple, OR;

   o  Equaling or being a sub-range of the I_local_iface_addr_list in a
      Local Interface Tuple, OR;

   o  Equaling or being a sub-range of the IR_local_iface_addr in a
      Removed Interface Address Tuple, OR;

   o  Equaling an AL_net_addr in a Local Attached Network Tuple.

   Addresses or network addresses with the following properties are
   considered as "partially owned" (which may include being fully owned)
   by a router when processing a received message:

   o  Overlapping (equaling or containing) its originator address, OR;

   o  Overlapping (equaling or containing) the O_orig_addr in an
      Originator Tuple, OR;

   o  Overlapping the I_local_iface_addr_list in a Local Interface
      Tuple, OR;

   o  Overlapping the IR_local_iface_addr in a Removed Interface Address
      Tuple, OR;

   o  Equaling or having as a sub-range an AL_net_addr in a Local
      Attached Network Tuple.

12.  Packets and Messages

   The packet and message format used by this protocol is defined in
   [RFC5444].  Except as otherwise noted, options defined in [RFC5444]
   may be freely used, in particular alternative formats defined by
   packet, message, Address Block and TLV flags.



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   Routers using this protocol exchange information through messages.
   The message types used by this protocol are the HELLO message and the
   TC message.  The HELLO message is defined by [NHDP] and extended by
   this specification, see Section 14.  The TC message is defined by
   this specification, see Section 15.

   One or more messages sent by a router at the same time SHOULD be
   combined into a single packet, subject to any constraints on maximum
   packet size (such as derived from the MTU over a local single hop)
   that MAY be imposed.  These messages may have originated at the
   sending router, or have originated at another router and are being
   forwarded by the sending router.  Messages with different originating
   routers MAY be combined for transmission within the same packet.
   Messages from other protocols defined using [RFC5444], including but
   not limited to [NHDP], MAY be combined for transmission within the
   same packet.  This specification does not define or use any contents
   of the Packet Header.

   Forwarded messages MAY be jittered as described in [RFC5148].  The
   value of MAXJITTER used in jittering a forwarded message MAY be based
   on information in that message (in particular any Message TLVs with
   Type = INTERVAL_TIME or Type = VALIDITY_TIME) or otherwise SHOULD be
   with a maximum delay of F_MAXJITTER.  A router MAY modify the jitter
   applied to a message in order to more efficiently combine messages in
   packets, as long as the maximum jitter is not exceeded.

   All references in this specification to TLVs that do not indicate a
   type extension, assume Type Extension = 0.  TLVs in processed
   messages with a type extension which is neither zero as so assumed,
   nor a specifically indicated non-zero type extension, are ignored.

13.  Message Processing and Forwarding

   This section describes the optimized flooding operation (MPR
   flooding) used when control messages, as instances of [RFC5444], are
   intended for MANET wide distribution.  This flooding mechanism
   defines when a received message is, or is not, processed and/or
   forwarded.

   This flooding mechanism is used by this protocol and MAY be used by
   extensions to this protocol which define, and hence own, other
   message types, to manage processing and/or forwarding of these
   messages.  This specification contains elements (P_type, RX_type,
   F_type) required only for such usage.

   This flooding mechanism is always used for TC messages (see
   Section 15).  Received HELLO messages (see Section 14 are, unless
   invalid, always processed, and never forwarded by this flooding



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   mechanism.  They thus do not need to be recorded in the Received
   Message Information Base.

   The processing selection and forwarding mechanisms are designed to
   only need to parse the Message Header in order to determine whether a
   message is to be processed and/or forwarded, and not to have to parse
   the Message Body even if the message is forwarded (but not
   processed).  An implementation MAY only parse the Message Body if
   necessary, or MAY always parse the Message Body and reject the
   message if it cannot be so parsed, or any other error is identified.

   An implementation MUST discard the message silently if it is unable
   to parse the Message Header or (if attempted) the Message Body, or if
   a message (other than a HELLO message) does not include a message
   sequence number.

13.1.  Actions when Receiving a Message

   On receiving a message of a type specified to be using this
   mechanism, which includes the TC messages defined in this
   specification, a router MUST perform the following:

   1.  If the router recognizes from the originator address of the
       message that the message is one which the receiving router itself
       originated (i.e., the message originator address is the
       originator address of this router, or is an O_orig_addr in an
       Originator Tuple) then the message MUST be silently discarded.

   2.  Otherwise:

       1.  If the message is of a type which may be processed, then the
           message is considered for processing according to
           Section 13.2.

       2.  If the message is of a type which may be forwarded, AND:

           +  <msg-hop-limit> is present and <msg-hop-limit> > 1, AND;

           +  <msg-hop-count> is not present or <msg-hop-count> < 255;

           then the message is considered for forwarding according to
           Section 13.3.

13.2.  Message Considered for Processing

   If a message (the "current message") is considered for processing,
   then the following tasks MUST be performed:




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   1.  If the sending address (i.e., the source address of the IP
       datagram containing the current message) does not match (taking
       into account any address prefix) a network address in an
       L_neighbor_iface_addr_list of a Link Tuple, with L_status =
       SYMMETRIC, in the Link Set for the OLSRv2 interface on which the
       current message was received (the "receiving interface") then
       processing the current message is OPTIONAL.  If the current
       message is not processed then the following steps are not carried
       out.

   2.  If a Processed Tuple exists with:

       *  P_type = the Message Type of the current message, AND;

       *  P_orig_addr = the originator address of the current message,
          AND;

       *  P_seq_number = the message sequence number of the current
          message;

       then the current message MUST NOT be processed.

   3.  Otherwise:

       1.  Create a Processed Tuple with:

           +  P_type := the Message Type of the current message;

           +  P_orig_addr := the originator address of the current
              message;

           +  P_seq_number := the sequence number of the current
              message;

           +  P_time := current time + P_HOLD_TIME.

       2.  Process the current message according to its Message Type.
           For a TC message this is as defined in Section 15.4.

13.3.  Message Considered for Forwarding

   If a message (the "current message") is considered for forwarding,
   then the following tasks MUST be performed:

   1.  If the sending address (i.e., the source address of the IP
       datagram containing the current message) does not match (taking
       into account any address prefix) a network address in an
       L_neighbor_iface_addr_list of a Link Tuple, with L_status =



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       SYMMETRIC, in the Link Set for the OLSRv2 interface on which the
       current message was received (the "receiving interface") then the
       current message MUST be silently discarded.

   2.  Otherwise:

       1.  If a Received Tuple exists in the Received Set for the
           receiving interface, with:

           +  RX_type = the Message Type of the current message, AND;

           +  RX_orig_addr = the originator address of the current
              message, AND;

           +  RX_seq_number = the sequence number of the current
              message;

           then the current message MUST be silently discarded.

       2.  Otherwise:

           1.  Create a Received Tuple in the Received Set for the
               receiving interface with:

               -  RX_type := the Message Type of the current message;

               -  RX_orig_addr := originator address of the current
                  message;

               -  RX_seq_number := sequence number of the current
                  message;

               -  RX_time := current time + RX_HOLD_TIME.

           2.  If a Forwarded Tuple exists with:

               -  F_type = the Message Type of the current message, AND;

               -  F_orig_addr = the originator address of the current
                  message, AND;

               -  F_seq_number = the sequence number of the current
                  message.

               then the current message MUST be silently discarded.

           3.  Otherwise if the sending address matches (taking account
               of any address prefix) any network address in an



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               L_neighbor_iface_addr_list of a Link Tuple in the Link
               Set for the receiving OLSRv2 interface that has L_status
               = SYMMETRIC and whose corresponding Neighbor Tuple has
               N_mpr_selector = true, then:

               1.  Create a Forwarded Tuple with:

                   o  F_type := the Message Type of the current message;

                   o  F_orig_addr := originator address of the current
                      message;

                   o  F_seq_number := sequence number of the current
                      message;

                   o  F_time := current time + F_HOLD_TIME.

               2.  The Message Header of the current message is modified
                   by:

                   o  if present, decrement <msg-hop-limit> in the
                      Message Header by 1, AND;

                   o  if present, increment <msg-hop-count> in the
                      Message Header by 1.

               3.  The message is transmitted over all OLSRv2
                   interfaces, as described in Section 12.

14.  HELLO messages

   The HELLO message Message Type is owned by [NHDP], and thus HELLO
   messages are generated, transmitted, received and processed by
   [NHDP].  This protocol, as permitted by [NHDP], also uses HELLO
   messages, including adding to HELLO message generation, and
   implementing additional processing based on received HELLO messages.
   HELLO messages are not forwarded by [NHDP] or this specification.

14.1.  HELLO Message Generation

   An HELLO message is generated as defined in [NHDP], extended by the
   following elements being added to the HELLO message by this
   specification before the HELLO message is sent over an OLSRv2
   interface:

   o  A message originator address, recording this router's originator
      address.  This MUST use a <msg-orig-addr> element, unless:




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      *  The message specifies only a single local interface address
         (i.e., contains only one address object that is associated with
         an Address Block TLV with Type = LOCAL_IF, and which has no
         prefix length, or a maximum prefix length) which will then be
         interpreted as the message originator address, OR;

      *  The message does not include any local interface network
         addresses (i.e., has no address objects associated with an
         Address Block TLV with Type = LOCAL_IF), as permitted by the
         specification in [NHDP] when the router that generated the
         HELLO message has only one interface address and will use that
         as the sending address of the IP datagram in which the HELLO
         message is contained.  In this case that address will be
         interpreted as the message originator address.

   o  A Message TLV with Type := MPR_WILLING and Value := WILLINGNESS
      MUST be included, unless WILLINGNESS = WILL_DEFAULT (in which case
      it MAY be included).

   o  For each Neighbor Tuple with N_mpr = true, and for which one or
      more network addresses in its N_neighbor_addr_list are included as
      address objects in the HELLO message with an associated Address
      Block TLV with Type = LINK_STATUS and Value = SYMMETRIC, at least
      one, possibly more, of these address objects (including a
      different copy of that address object, in the same or a different
      Address Block) MUST be associated with an Address Block TLV with
      Type := MPR.  Address objects which do not satisfy this property
      MUST NOT be associated with an Address Block TLV with Type = MPR.

14.2.  HELLO Message TLVs

   This specification defines one Message TLV and one Address Block TLV
   that may be added to HELLO messages by this specification.

14.2.1.  Message TLVs

   This specification defines one Message TLV that may be included in a
   HELLO message:

   +-------------+--------------+--------------------------------------+
   |     Type    | Value Length | Value                                |
   +-------------+--------------+--------------------------------------+
   | MPR_WILLING |    1 octet   | Router parameter WILLINGNESS; unused |
   |             |              | bits (based on the maximum           |
   |             |              | willingness value WILL_ALWAYS) are   |
   |             |              | RESERVED and SHOULD be set to zero.  |
   +-------------+--------------+--------------------------------------+




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                    Table 1: MPR_WILLING TLV definition

14.2.2.  Address Block TLVs

   This specification defines one Address Block TLV that may be included
   in a HELLO message:

                      +------+--------------+-------+
                      | Type | Value Length | Value |
                      +------+--------------+-------+
                      |  MPR |   0 octets   | None. |
                      +------+--------------+-------+

                        Table 2: MPR TLV definition

14.3.  HELLO Message Transmission

   HELLO messages are scheduled and transmitted by [NHDP].  This
   protocol MAY require that an additional HELLO message is sent when
   the router's set of MPRs changes, in addition to the cases specified
   in [NHDP], and subject to the same constraints.

14.4.  HELLO Message Processing

   When received on an OLSRv2 interface, HELLO messages are made
   available to this protocol in two ways, both as permitted by [NHDP]:

   o  Such received HELLO messages MUST be made available to this
      protocol on reception, which allows them to be discarded before
      being processed by [NHDP], for example if the information added to
      the HELLO message by this protocol is inconsistent.

   o  Such received HELLO messages MUST be made available to OLSRv2
      after [NHDP] has completed its processing thereof, unless
      discarded as malformed by [NHDP], for processing by this protocol.

14.4.1.  HELLO Message Discarding

   In addition to the reasons specified in [NHDP] for discarding a HELLO
   message on reception, a HELLO message MUST be discarded before
   processing by [NHDP] or this specification if it:

   o  Has more than one Message TLV with Type = MPR_WILLING.

   o  Has a message originator address, or a network address
      corresponding to an address object associated with an Address
      Block TLV with Type = LOCAL_IF, that is partially owned by this
      router.  (Some of these cases are already excluded by [NHDP].)



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   o  Includes any address object associated with an Address Block TLV
      with Type = LINK_STATUS or Type = OTHER_NEIGHB that overlaps the
      message's originator address.

   o  Contains any address object associated with an Address Block TLV
      with Type = MPR that is not also associated with an Address Block
      TLV with Type = LINK_STATUS and Value = SYMMETRIC (including using
      a different copy of that address object, in the same or a
      different Address Block).

14.4.2.  HELLO Message Usage

   HELLO messages are first processed as specified in [NHDP].  That
   processing includes identifying (or creating) a Neighbor Tuple
   corresponding to the originator of the HELLO message (the "current
   Neighbor Tuple").  After this, the following processing MUST also be
   performed:

   1.  If the HELLO message has a well-defined message originator
       address, i.e., has an <msg-orig-addr> element or has zero or one
       network addresses associated with a TLV with Type = LOCAL_IF:

       1.  Remove any other Neighbor Tuple with N_orig_addr = message
           originator address, taking any consequent action (including
           removing one or more Link Tuples) as specified in [NHDP].

       2.  The current Neighbor Tuple is then updated according to:

           1.  N_orig_addr := message originator address;

           2.  Update N_willingness as described in Section 14.4.2.1;

           3.  Update N_mpr_selector as described in Section 14.4.2.2.

   2.  If there are any changes to the router's Information Bases, then
       perform the processing defined in Section 16.

14.4.2.1.  Updating Willingness

   N_willingness in the current Neighbor Tuple is updated as follows:

   1.  If the HELLO message contains a Message TLV with Type =
       MPR_WILLING then N_willingness := the value of that TLV;

   2.  Otherwise, N_willingness := WILL_DEFAULT.






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14.4.2.2.  Updating MPR Selector Status

   N_mpr_selector is updated as follows:

   1.  If a router finds an address object representing any of its local
       interface network addresses (i.e., those contained in the
       I_local_iface_addr_list of an OLSRv2 interface) with an
       associated Address Block TLV with Type = MPR in the HELLO message
       (indicating that the originating router has selected the
       receiving router as an MPR) then, for the current Neighbor Tuple:

       *  N_mpr_selector := true

   2.  Otherwise (i.e., if no such address object and Address Block TLV
       was found) if a router finds an address object representing any
       of its local interface network addresses (i.e., those contained
       in the I_local_iface_addr_list of an OLSRv2 interface) with an
       associated Address Block TLV with Type = LINK_STATUS and Value =
       SYMMETRIC in the HELLO message, then for the current Neighbor
       Tuple:

       *  N_mpr_selector := false

       *  N_advertised := false

15.  TC Messages

   This protocol defines, and hence owns, the TC message type (see
   Section 23).  Thus, as specified in [RFC5444], this protocol
   generates and transmits all TC messages, receives all TC messages and
   is responsible for determining whether and how each TC message is to
   be processed (updating the Topology Information Base) and/or
   forwarded, according to this specification.

15.1.  TC Message Generation

   A TC message is a message as defined in [RFC5444].  A generated TC
   message MUST contain the following elements as defined in [RFC5444]:

   o  A message originator address, recording this router's originator
      address.  This MUST use a <msg-orig-addr> element.

   o  <msg-seq-num> element containing the message sequence number.

   o  A <msg-hop-limit> element, containing TC_HOP_LIMIT.  A router MAY
      use the same or different values of TC_HOP_LIMIT in its TC
      messages, see Section 5.8.




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   o  A <msg-hop-count> element, containing zero, if the message
      contains a TLV with either Type = VALIDITY_TIME or Type =
      INTERVAL_TIME (as specified in [RFC5497]) indicating more than one
      time value according to distance.  A TC message MAY contain such a
      <msg-hop-count> element even if it does not need to.

   o  A single Message TLV with Type := CONT_SEQ_NUM and Value := ANSN
      from the Neighbor Information Base.  If the TC message is complete
      then this Message TLV MUST have Type Extension := COMPLETE,
      otherwise it MUST have Type Extension := INCOMPLETE.  (Exception:
      a TC message MAY omit such a Message TLV if the TC message does
      not include any address objects with an associated Address Block
      TLV with Type = NBR_ADDR_TYPE or Type = GATEWAY.)

   o  A single Message TLV with Type := VALIDITY_TIME, as specified in
      [RFC5497].  If all TC messages are sent with the same hop limit
      then this TLV MUST have a value encoding the period T_HOLD_TIME.
      If TC messages are sent with different hop limits (more than one
      value of TC_HOP_LIMIT) then this TLV MUST specify times that vary
      with the number of hops distance appropriate to the chosen pattern
      of TC message hop limits, as specified in [RFC5497]; these times
      SHOULD be appropriate multiples of T_HOLD_TIME.  The options
      included in [RFC5497] for representing zero and infinite times
      MUST NOT be used.

   o  If the TC message is complete, all network addresses which are the
      N_orig_addr of a Neighbor Tuple with N_advertised = true, MUST be
      represented by address objects in one or more Address Blocks.  If
      the TC message is incomplete then any such address objects MAY be
      included.  At least one copy of each such address object that is
      included MUST be associated with an Address Block TLV with Type :=
      NBR_ADDR_TYPE, and Value := ORIGINATOR, or with Value :=
      ROUTABLE_ORIG if that address object is also to be associated with
      Value = ROUTABLE.

   o  If the TC message is complete, all routable addresses which are in
      the N_neighbor_addr_list of a Neighbor Tuple with N_advertised =
      true MUST be represented by address objects in one or more Address
      Blocks.  If the TC message is incomplete then any such address
      objects MAY be included.  At least one copy of each such address
      object MUST be associated with an Address Block TLV with Type =
      NBR_ADDR_TYPE, and Value = ROUTABLE, or with Value = ROUTABLE_ORIG
      if also to be associated with Value = ORIGINATOR.

   o  If the TC message is complete, all network addresses which are the
      AL_net_addr of a Local Attached Network Tuple MUST be represented
      by address objects in one or more Address Blocks.  If the TC
      message is incomplete then any such address objects MAY be



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      included.  At least one copy of each such address object MUST be
      associated with an Address Block TLV with Type := GATEWAY, and
      Value := AN_dist.

   A TC message MAY contain:

   o  A single Message TLV with Type := INTERVAL_TIME, as specified in
      [RFC5497].  If all TC messages are sent with the same hop limit
      then this TLV MUST have a value encoding the period TC_INTERVAL.
      If TC messages are sent with different hop limits, then this TLV
      MUST specify times that vary with the number of hops distance
      appropriate to the chosen pattern of TC message hop limits, as
      specified in [RFC5497]; these times SHOULD be appropriate
      multiples of TC_INTERVAL.  The options included in [RFC5497] for
      representing zero and infinite times MUST NOT be used.

15.2.  TC Message TLVs

   This specification defines one Message TLV and two Address Block TLV
   that may be used in TC messages by this specification.

15.2.1.  Message TLVs

   In a TC message, a router MAY include at most one (and except in an
   exceptional case MUST include exactly one) CONT_SEQ_NUM Message TLV
   as specified in Table 3.

   +--------------+--------------+-------------------------------------+
   |     Type     | Value Length | Value                               |
   +--------------+--------------+-------------------------------------+
   | CONT_SEQ_NUM |   2 octets   | The ANSN contained in the Neighbor  |
   |              |              | Information Base.                   |
   +--------------+--------------+-------------------------------------+

                   Table 3: CONT_SEQ_NUM TLV definition

15.2.2.  Address Block TLVs

   In a TC message, a router MAY include NBR_ADDR_TYPE Address Block
   TLV(s) as specified in Table 4.











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   +---------------+--------------+------------------------------------+
   |      Type     | Value Length | Value                              |
   +---------------+--------------+------------------------------------+
   | NBR_ADDR_TYPE |    1 octet   | ORIGINATOR indicates that the      |
   |               |              | corresponding address (which MUST  |
   |               |              | have maximum prefix length) is an  |
   |               |              | originator address, ROUTABLE       |
   |               |              | indicates that the corresponding   |
   |               |              | network address is a routable      |
   |               |              | address of an interface,           |
   |               |              | ROUTABLE_ORIG indicates that the   |
   |               |              | corresponding address is both      |
   +---------------+--------------+------------------------------------+

                   Table 4: NBR_ADDR_TYPE TLV definition

   If an address is both a originator address and a routable address,
   then it may be associated with either one Address Block TLV with Type
   := NBR_ADDR_TYPE and Value := ROUTABLE_ORIG, or with two Address
   Block TLVs with Type:= NBR_ADDR_TYPE, one with Value := ORIGINATOR
   and one with Value := ROUTABLE.

   In a TC message, a router MAY include GATEWAY Address Block TLV(s) as
   specified in Table 5.

     +---------+--------------+-------------------------------------+
     |   Type  | Value Length | Value                               |
     +---------+--------------+-------------------------------------+
     | GATEWAY |    1 octet   | Number of hops to attached network. |
     +---------+--------------+-------------------------------------+

                                  Table 5

   All address objects included in a TC message according to this
   specification MUST be associated either with at least one TLV with
   Type := NBR_ADDR_TYPE or with a TLV with Type := GATEWAY, but not
   both.  Any other address objects MAY be included in Address Blocks in
   a TC message, but are ignored by this specification.

15.3.  TC Message Transmission

   A router with one or more OLSRv2 interfaces, and with any Neighbor
   Tuples with N_advertised = true, or with a non-empty Local Attached
   Network Set MUST generate TC messages.  A router which does not have
   such information to advertise SHOULD also generate "empty" TC
   messages for a period A_HOLD_TIME after it last generated a non-empty
   TC message.




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   Complete TC messages are generated and transmitted periodically on
   all OLSRv2 interfaces, with a default interval between two
   consecutive TC transmissions by the same router of TC_INTERVAL.

   TC messages MAY be generated in response to a change in the
   information which they are to advertise, indicated by a change in the
   ANSN in the Neighbor Information Base.  In this case a router MAY
   send a complete TC message, and if so MAY re-start its TC message
   schedule.  Alternatively a router MAY send an incomplete TC message
   with at least the newly advertised network addresses (i.e., not
   previously, but now, an N_orig_addr or in an N_neighbor_addr_list in
   a Neighbor Tuple with N_advertised = true, or an AL_net_addr) in its
   Address Blocks, with associated Address Block TLV(s).  Note that a
   router cannot report removal of advertised content using an
   incomplete TC message.

   When sending a TC message in response to a change of advertised
   network addresses, a router MUST respect a minimum interval of
   TC_MIN_INTERVAL between generated TC messages.  Sending an incomplete
   TC message MUST NOT cause the interval between complete TC messages
   to be increased, and thus a router MUST NOT send an incomplete TC
   message if within TC_MIN_INTERVAL of the next scheduled complete TC
   message.

   The generation of TC messages, whether scheduled or triggered by a
   change of contents, MAY be jittered as described in [RFC5148].  The
   values of MAXJITTER used SHOULD be:

   o  TP_MAXJITTER for periodic TC message generation;

   o  TT_MAXJITTER for responsive TC message generation.

15.4.  TC Message Processing

   On receiving a TC message, the receiving router MUST then follow the
   processing and forwarding procedure, defined in Section 13.

   If the message is considered for processing (Section 13.2), then a
   router MUST first check if the message is invalid for processing by
   this router, as defined in Section 15.4.1.  A router MAY make a
   similar check before considering a message for forwarding, it MUST
   make those aspects of the check that apply to elements in the Message
   Header.

   If the TC message is not invalid, then the TC message type specific
   processing, described in Section 15.4.2 MUST be applied.  This will
   update its appropriate Interface Information Base and its Router
   Information Base.  Following this, if there are any changes in these



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   Information Bases, then the processing in Section 16 MUST be
   performed.

15.4.1.  Invalid Message

   A received TC message is invalid for processing by this router if the
   message:

   o  The address length as specified in the Message Header is not equal
      to the length of the addresses used by this router.

   o  Does not include a message originator address and a message
      sequence number.

   o  Does not include a hop count, and contains a multi-value TLV with
      Type = VALIDITY_TIME or Type = INTERVAL_TIME, as defined in
      [RFC5497].

   o  Does not have exactly one Message TLV with Type = VALIDITY_TIME.

   o  Has more than one Message TLV with Type = INTERVAL_TIME.

   o  Does not have a Message TLV with Type = CONT_SEQ_NUM and Type
      Extension = COMPLETE or Type Extension = INCOMPLETE, and contains
      at least one address object associated with an Address Block TLV
      with Type = NBR_ADDR_TYPE or Type = GATEWAY.

   o  Has more than one Message TLV with Type = CONT_SEQ_NUM and Type
      Extension = COMPLETE or Type Extension = INCOMPLETE.

   o  Has a message originator address that is partially owned by this
      router.

   o  Includes any address object with a prefix length which is not
      maximal (equal to the address length, in bits), associated with an
      Address Block TLV with Type = NBR_ADDR_TYPE and Value = ORIGINATOR
      or Value = ROUTABLE_ORIG.

   o  Includes any address object that represents a non-routable
      address, associated with an Address Block TLV with Type =
      NBR_ADDR_TYPE and Value = ROUTABLE or Value = ROUTABLE_ORIG.

   o  Includes any address object associated with an Address Block TLV
      with Type = NBR_ADDR_TYPE or Type = GATEWAY that also represents
      the message's originator address.

   o  Associates any address object (including different copies of an
      address object, in the same or different Address Blocks) with more



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      than one single value using one or more Address Block TLV(s) with
      Type = GATEWAY.

   o  Associates any address object (including different copies of an
      address object, in the same or different Address Blocks) with
      Address Block TLVs with Type = NBR_ADDR_TYPE and Type = GATEWAY.

   A router MAY recognize additional reasons for identifying that a
   message is invalid.  An invalid message MUST be silently discarded,
   without updating the router's Information Bases.

15.4.2.  TC Message Processing Definitions

   When, according to Section 13.2, a TC message is to be "processed
   according to its type", this means that:

   o  If the TC message contains a Message TLV with Type = CONT_SEQ_NUM
      and Type Extension = COMPLETE, then processing according to
      Section 15.4.3 and then according to Section 15.4.4 is carried
      out.

   o  If the TC message contains a Message TLV with Type = CONT_SEQ_NUM
      and Type Extension = INCOMPLETE, then only processing according to
      Section 15.4.3 is carried out.

   For the purposes of this section:

   o  "validity time" is calculated from a VALIDITY_TIME Message TLV in
      the TC message according to the specification in [RFC5497].  All
      information in the TC message has the same validity time.

   o  "received ANSN" is defined as being the value of a Message TLV
      with Type = CONT_SEQ_NUM.

   o  Comparisons of sequence numbers are carried out as specified in
      Section 20.

15.4.3.  Initial TC Message Processing

   The TC message is processed as follows:

   1.  The Advertising Remote Router Set is updated according to
       Section 15.4.3.1.  If the TC message is indicated as discarded in
       that processing then the following steps are not carried out.

   2.  The Router Topology Set is updated according to Section 15.4.3.2.





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   3.  The Routable Address Topology Set is updated according to
       Section 15.4.3.3.

   4.  The Attached Network Set is updated according to
       Section 15.4.3.4.

15.4.3.1.  Populating the Advertising Remote Router Set

   The router MUST update its Advertising Remote Router Set as follows:

   1.  If there is an Advertising Remote Router Tuple with:

       *  AR_orig_addr = message originator address, AND;

       *  AR_seq_number > received ANSN,

       then the TC message MUST be discarded.

   2.  Otherwise:

       1.  If there is no Advertising Remote Router Tuple such that:

           +  AR_orig_addr = message originator address;

           then create an Advertising Remote Router Tuple with:

           +  AR_orig_addr := message originator address.

       2.  This Advertising Remote Router Tuple (existing or new) is
           then modified as follows:

           +  AR_seq_number := received ANSN;

           +  AR_time := current time + validity time.

15.4.3.2.  Populating the Router Topology Set

   The router MUST update its Router Topology Set as follows:

   1.  For each address (henceforth advertised address) corresponding to
       one or more address objects with an associated Address Block TLV
       with Type = NBR_ADDR_TYPE and Value = ORIGINATOR or Value =
       ROUTABLE_ORIG, and that is not partially owned by this router,
       perform the following processing:

       1.  If there is no Router Topology Tuple such that:





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           +  TR_from_orig_addr = message originator address, AND;

           +  TR_to_orig_addr = advertised address,

           then create a new Router Topology Tuple with:

           +  TR_from_orig_addr := message originator address;

           +  TR_to_orig_addr := advertised address.

       2.  This Router Topology Tuple (existing or new) is then modified
           as follows:

           +  TR_seq_number := received ANSN;

           +  TR_time := current time + validity time.

15.4.3.3.  Populating the Routable Address Topology Set

   The router MUST update its Routable Address Topology Set as follows:

   1.  For each network address (henceforth advertised address)
       corresponding to one or more address objects with an associated
       Address Block TLV with Type = NBR_ADDR_TYPE and Value = ROUTABLE
       or Value = ROUTABLE_ORIG, and that is not partially owned by this
       router, perform the following processing:

       1.  If there is no Routable Address Topology Tuple such that:

           +  TA_from_orig_addr = message originator address, AND;

           +  TA_dest_addr = advertised address,

           then create a new Routable Address Topology Tuple with:

           +  TA_from_orig_addr := message originator address;

           +  TA_dest_addr := advertised address.

       2.  This Routable Address Topology Tuple (existing or new) is
           then modified as follows:

           +  TA_seq_number := received ANSN;

           +  TA_time := current time + validity time.






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15.4.3.4.  Populating the Attached Network Set

   The router MUST update its Attached Network Set as follows:

   1.  For each network address (henceforth attached address)
       corresponding to one or more address objects with an associated
       Address Block TLV with Type = GATEWAY, and that is not fully
       owned by this router, perform the following processing:

       1.  If there is no Attached Network Tuple such that:

           +  AN_net_addr = attached address, AND;

           +  AN_orig_addr = message originator address,

           then create a new Attached Network Tuple with:

           +  AN_net_addr := attached address;

           +  AN_orig_addr := message originator address.

       2.  This Attached Network Tuple (existing or new) is then
           modified as follows:

           +  AN_dist := the Value of the associated GATEWAY TLV;

           +  AN_seq_number := received ANSN;

           +  AN_time := current time + validity time.

15.4.4.  Completing TC Message Processing

   The TC message is processed as follows:

   1.  The Router Topology Set is updated according to Section 15.4.4.1.

   2.  The Routable Address Topology Set is updated according to
       Section 15.4.4.2.

   3.  The Attached Network Set is updated according to
       Section 15.4.4.3.

15.4.4.1.  Purging the Router Topology Set

   The Router Topology Set MUST be updated as follows:

   1.  Any Router Topology Tuples with:




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       *  TR_from_orig_addr = message originator address, AND;

       *  TR_seq_number < received ANSN,

       MUST be removed.

15.4.4.2.  Purging the Routable Address Topology Set

   The Routable Address Topology Set MUST be updated as follows:

   1.  Any Routable Address Topology Tuples with:

       *  TA_from_orig_addr = message originator address, AND;

       *  TA_seq_number < received ANSN,

       MUST be removed.

15.4.4.3.  Purging the Attached Network Set

   The Attached Network Set MUST be updated as follows:

   1.  Any Attached Network Tuples with:

       *  AN_orig_addr = message originator address, AND;

       *  AN_seq_number < received ANSN,

       MUST be removed.

16.  Information Base Changes

   The changes described in the following sections MUST be carried out
   when any Information Base changes as indicated.

16.1.  Originator Address Changes

   If the router changes originator address, then:

   1.  If there is no Originator Tuple with:

       *  O_orig_addr = old originator address

       then create an Originator Tuple with:

       *  O_orig_addr := old originator address

       The Originator Tuple (existing or new) with:



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       *  O_orig_addr = new originator address

       is then modified as follows:

       *  O_time := current time + O_HOLD_TIME

16.2.  Neighbor State Changes

   The N_mpr_selector and N_advertised flags in Neighbor Tuples MUST be
   maintained according to the following rules:

   1.  If N_symmetric = false, then N_mpr_selector = false and
       N_advertised = false.

   2.  If N_mpr_selector = true, then N_advertised = true.

   3.  In other cases (i.e., N_symmetric = true and N_mpr_selector =
       false) a router MAY select N_advertised = true or N_advertised =
       false.  The more neighbors that are advertised, the larger TC
       messages become, but the more redundancy is available for
       routing.  A router SHOULD consider the nature of its network in
       making such a decision, and SHOULD avoid unnecessary changes in
       advertising status, which may result both in additional TC
       messages having to be sent by its neighbors, and in unnecessary
       changes to routing, which will have similar effects to other
       forms of topology changes in the MANET.

16.3.  Advertised Neighbor Changes

   The router MUST increment the ANSN in the Neighbor Information Base
   whenever:

   1.  Any Neighbor Tuple changes its N_advertised value.

   2.  N_orig_addr is changed, or any routable address is added to or
       removed from any Neighbor Tuple with N_advertised = true.

   3.  Any Neighbor Tuple with N_advertised = true is removed.

   4.  There is any change to the Local Attached Network Set.

16.4.  Advertising Remote Router Tuple Expires

   The Router Topology Set, the Routable Address Topology Set and the
   Attached Network Set MUST be changed when an Advertising Remote
   Router Tuple expires (AR_time is reached).  The following changes are
   required before the Advertising Remote Router Tuple is removed:




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   1.  All Router Topology Tuples with:

       *  TR_from_orig_addr = AR_orig_addr of the Advertising Remote
          Router Tuple

       are removed.

   2.  All Routable Address Topology Tuples with:

       *  TA_from_orig_addr = AR_orig_addr of the Advertising Remote
          Router Tuple

       are removed.

   3.  All Attached Network Tuples with:

       *  AN_orig_addr = AR_orig_addr of the Advertising Remote Router
          Tuple

       are removed.

16.5.  Neighborhood Changes and MPR Updates

   The set of symmetric 1-hop neighbors selected as MPRs MUST satisfy
   the conditions defined in Section 17.  To ensure this:

   1.  The set of MPRs of a router MUST be recalculated if:

       *  a Link Tuple is added with L_status = SYMMETRIC, OR;

       *  a Link Tuple with L_status = SYMMETRIC is removed, OR;

       *  a Link Tuple with L_status = SYMMETRIC changes to having
          L_status = HEARD or L_status = LOST, OR;

       *  a Link Tuple with L_status = HEARD or L_status = LOST changes
          to having L_status = SYMMETRIC, OR;

       *  a 2-Hop Tuple is added or removed, OR;

       *  the N_willingness of a Neighbor Tuple with N_symmetric = true
          changes from WILL_NEVER to any other value, OR;

       *  the N_willingness of a Neighbor Tuple with N_mpr = true
          changes to WILL_NEVER from any other value, OR;

       *  the N_willingness of a Neighbor Tuple with N_symmetric = true
          and N_mpr = false changes to WILL_ALWAYS from any other value.



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   2.  Otherwise, the set of MPRs of a router MAY be recalculated if the
       N_willingness of a Neighbor Tuple with N_symmetric = true changes
       in any other way; it SHOULD be recalculated if N_mpr = false and
       this is an increase in N_willingness or if N_mpr = true and this
       is a decrease in N_willingness.

   If the set of MPRs of a router is recalculated, this MUST be as
   described in Section 17.  Before that calculation, the N_mpr of all
   Neighbor Tuples are set false (although the previous values of N_mpr
   MAY be used by an algorithm that minimizes changes to the set of
   MPRs).  After that calculation the N_mpr of all Neighbor Tuples
   representing symmetric 1-hop neighbors that are chosen as MPRs, are
   set true.

16.6.  Routing Set Updates

   The Routing Set MUST be updated, as described in Section 18 when
   changes in the Local Information Base, the Neighborhood Information
   Base or the Topology Information Base indicate a change of the known
   symmetric links and/or attached networks in the MANET, hence changing
   the Topology Graph.  It is sufficient to consider only changes which
   affect at least one of:

   o  The Local Interface Set, if the change removes any network address
      in an I_local_iface_addr_list.  In this case, unless the OLSRv2
      interface is removed, it may not be necessary to do more than
      replace such network addresses, if used, by an alternative network
      address from the same I_local_iface_addr_list.

   o  The Local Attached Set, if the change removes any AL_net_addr
      which is also an AN_net_addr.  In this case it may not be
      necessary to do more than add Routing Tuples with R_dest_addr
      equal to that AN_net_addr.

   o  The Link Set of any OLSRv2 interface, and to consider only Link
      Tuples which have, or just had, L_status = SYMMETRIC (including
      removal of such Link Tuples).

   o  The Neighbor Set of the router, and to consider only Neighbor
      Tuples that have, or just had, N_symmetric = true, and do not have
      N_orig_addr = unknown.

   o  The 2-Hop Set of any OLSRv2 interface, if used in the creation of
      the Routing Set.

   o  The Router Topology Set of the router.





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   o  The Routable Address Topology Set of the router.

   o  The Attached Network Set of the router.

17.  Selecting MPRs

   Each router MUST select, from among its willing symmetric 1-hop
   neighbors, a subset of these routers as MPRs.  Only MPRs forward
   control messages flooded through the MANET, thus effecting a flooding
   reduction, an optimization of the classical flooding mechanism, known
   as MPR flooding.  MPRs MAY also be used to effect a topology
   reduction in the MANET.  Consequently, while it is not essential that
   the set of MPRs is minimal, keeping the number of MPRs small ensures
   that the overhead is kept at a minimum.

   A router MUST select MPRs for each of its OLSRv2 interfaces, but then
   forms the union of those sets as its single set of MPRs.  This union
   MUST include all symmetric 1-hop neighbors with willingness
   WILL_ALWAYS.  Only this overall set of MPRs is relevant, the recorded
   and used MPR relationship is one of routers, not interfaces.  Routers
   MAY select their MPRs by any process which satisfies the conditions
   which follow.  Routers can freely interoperate whether they use the
   same or different MPR selection algorithms.

   For each OLSRv2 interface a router MUST select a set of MPRs.  This
   set MUST have the properties that:

   o  All of the selected MPRs are willing symmetric 1-hop neighbors,
      AND;

   o  If the selecting router sends a message on that OLSRv2 interface,
      and that message is successfully forwarded by all of the selected
      MPRs for that interface, then all symmetric strict 2-hop neighbors
      of the selecting router through that OLSRv2 interface will receive
      that message over a symmetric link.

   When a router selects its set of MPRs it MAY consider any other
   characteristics of its neighbors that it is aware of.  In particular
   it SHOULD consider the willingness of the neighbor, as recorded by
   the corresponding N_willingness value, preferring neighbors with
   higher values of N_willingness, but MAY consider other
   characteristics to have a greater significance.

   Note that it is always possible to select a valid set of MPRs.  The
   set of all willing symmetric 1-hop neighbors of a router is a
   (maximal) valid set of MPRs for that router.  However a router SHOULD
   NOT select a symmetric 1-hop neighbor with N_willingness !=
   WILL_ALWAYS as an MPR if there are no symmetric strict 2-hop



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   neighbors with a symmetric link to that symmetric 1-hop neighbor.
   Thus a router with no symmetric 1-hop neighbors with N_willingness =
   WILL_ALWAYS and with no symmetric strict 2-hop neighbors SHOULD NOT
   select any MPRs.

   A router MAY select its MPRs for each OLSRv2 interface independently,
   or it MAY coordinate its MPR selections across its OLSRv2 interfaces,
   as long as the required condition is satisfied for each OLSRv2
   interface.  Each router MAY select its MPRs independently from the
   MPR selection by other routers, or it MAY, for example, give
   preference to routers that either are, or are not, already selected
   as MPRs by other routers.

   When selecting MPRs for each OLSRv2 interface independently, this MAY
   be done using information from the Link Set and 2-Hop Set of that
   OLSRv2 interface only, and the Neighbor Set of the router
   (specifically the N_willingness elements).

   The selection of MPRs is recorded in the Neighbor Set of the router,
   by setting N_mpr = true for any selected MPR (on any OLSRv2
   interface) and ensuring that N_mpr = false otherwise.  A selected MPR
   MUST be a willing symmetric 1-hop neighbor (i.e., MUST have
   corresponding N_symmetric = true, and corresponding N_willingness !=
   WILL_NEVER).  Note that although selected per OLSRv2 interface, MPRs
   are recorded and used independent of interface, i.e., a router's set
   of MPRs is the union of the sets of MPRs selected per OLSRv2
   interface.

   A router MUST recalculate its MPRs whenever the currently selected
   set of MPRs does not still satisfy the required conditions.  It MAY
   recalculate its MPRs if the current set of MPRs is still valid, but
   could be more efficient.  Sufficient conditions to recalculate a
   router's set of MPRs are given in Section 16.5.

   An example algorithm that creates a set of MPRs that satisfies the
   required conditions is given in Appendix A.

18.  Routing Set Calculation

   The Routing Set of a router is populated with Routing Tuples that
   represent paths from that router to all destinations in the network.
   These paths are calculated based on the Network Topology Graph, which
   is constructed from information in the Information Bases, obtained
   via HELLO and TC message exchange.

   Changes to the Routing Set do not require any messages to be
   transmitted.  The state of the Routing Set SHOULD, however, be
   reflected in IP's routing table by adding and removing entries from



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   IP's routing table as appropriate.  Only appropriate Routing Tuples
   (in particular only those that represent local links or paths to
   routable addresses) need be reflected in IP's routing table.

18.1.  Network Topology Graph

   The Network Topology Graph is formed from information from the
   router's Local Interface Set, Link Sets, Neighbor Set, Router
   Topology Set, Routable Address Topology Set and Attached Network Set.
   The Network Topology Graph MAY also use information from the router's
   2-Hop Sets.  The Network Topology Graph forms the router's
   topological view of the network in form of a directed graph.  The
   Network Topology Graph has a "backbone" (within which minimum
   distance routes will be constructed) containing the following edges:

   o  Edges X -> Y for all possible Y, and one X per Y, such that:

      *  Y is the N_orig_addr of a Neighbor Tuple, AND;

      *  N_orig_addr is not unknown;

      *  X is in the I_local_iface_addr_list of a Local Interface Tuple,
         AND;

      *  There is a Link Tuple with L_status = SYMMETRIC such that this
         Neighbor Tuple and this Local Interface Tuple correspond to it.
         A network address from L_neighbor_iface_addr_list will be
         denoted R in this case.

      It SHOULD be preferred, where possible, to select R = S and X from
      the Local Interface Tuple corresponding to the Link Tuple from
      which R was selected.

   o  All edges W -> U such that:

      *  W is the TR_from_orig_addr of a Router Topology Tuple, AND;

      *  U is the TR_to_orig_addr of the same Router Topology Tuple.

   The Network Topology Graph is further "decorated" with the following
   edges.  If a network address S, V, Z or T equals a network address Y
   or W, then the edge terminating in the network address S, V, Z or T
   MUST NOT be used in any path.

   o  Edges X -> S for all possible S, and one X per S, such that:

      *  S is in the N_neighbor_addr_list of a Neighbor Tuple, AND;




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      *  X is in the I_local_iface_addr_list of a Local Interface Tuple,
         AND;

      *  There is a Link Tuple with L_status = SYMMETRIC such that this
         Neighbor Tuple and this Local Interface Tuple correspond to it.
         A network address from L_neighbor_iface_addr_list will be
         denoted R in this case.

      It SHOULD be preferred, where possible, to select R = S and X from
      the Local Interface Tuple corresponding to the Link Tuple from
      which R was selected.

   o  All edges W -> V such that:

      *  W is the TA_from_orig_addr of a Routable Address Topology
         Tuple, AND;

      *  V is the TA_dest_addr of the same Routable Address Topology
         Tuple.

   o  All edges W -> T such that:

      *  W is the AN_orig_addr of an Attached Network Tuple, AND;

      *  T is the AN_net_addr of the same Attached Network Tuple.

   o  OPTIONALLY, all edges Y -> Z such that:

      *  Z is a routable address and is the N2_2hop_addr of a 2-Hop
         Tuple, AND;

      *  Y is the N_orig_addr of the corresponding Neighbor Tuple, AND;

      *  This Neighbor Tuple has N_willingness not equal to WILL_NEVER.

      A path terminating with such an edge SHOULD NOT be used in
      preference to any other path.

   Any part of the Topology Graph which is not connected to a local
   network address X is not used.  Only one selection X SHOULD be made
   from each I_local_iface_addr_list, and only one selection R SHOULD be
   made from any L_neighbor_iface_addr_list.  All edges have a cost (hop
   count) of one, except edges W -> T which each have a cost (hop count)
   equal to the appropriate value of AN_dist.







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18.2.  Populating the Routing Set

   The Routing Set MUST contain the shortest paths for all destinations
   from all local OLSRv2 interfaces using the Network Topology Graph.
   This calculation MAY use any algorithm, including any means of
   choosing between paths of equal length.

   Using the notation of Section 18.1, initially "backbone" paths using
   only edges X -> Y and W -> U need be constructed (using a minimum
   distance algorithm).  Then paths using only a final edge of the other
   types may be added.  These MUST NOT replace backbone paths with the
   same destination (and paths terminating in an edge Y -> Z SHOULD NOT
   replace paths with any other form of terminating edge).

   Each path will correspond to a Routing Tuple.  These will be of two
   types.  The first type will represent single edge paths, of type X ->
   S or X -> Y, by:

   o  R_local_iface_addr := X;

   o  R_next_iface_addr := R;

   o  R_dest_addr := S or Y;

   o  R_dist := 1,

   where R is as defined in Section 18.1 for these types of edges.

   The second type will represent a multiple edge path, which will
   always have first edge of type X -> Y, and will have final edge of
   type W -> U, W -> V, W -> T or Y -> Z. The Routing Tuple will be:

   o  R_local_iface_addr := X;

   o  R_next_iface_addr := Y;

   o  R_dest_addr := U, V, T or Z;

   o  R_dist := the total hop count of the path.

   Finally, Routing Tuples of the second type whose R_dest_addr is not
   routable MAY be discarded.

   An example algorithm for calculating the Routing Set of a router is
   given in Appendix B.






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19.  Proposed Values for Parameters and Constants

   This protocol uses all parameters and constants defined in [NHDP] and
   additional parameters and constants defined in this document.  All
   but one (RX_HOLD_TIME) of these additional parameters are router
   parameters as defined in [NHDP].  These proposed values of the
   additional parameters are appropriate to the case where all
   parameters (including those defined in [NHDP]) have a single value.
   Proposed values for parameters defined in [NHDP] are given in that
   document.

19.1.  Local History Time Parameters

   o  O_HOLD_TIME := 30 seconds

19.2.  Message Interval Parameters

   o  TC_INTERVAL := 5 seconds

   o  TC_MIN_INTERVAL := TC_INTERVAL/4

19.3.  Advertised Information Validity Time Parameters

   o  T_HOLD_TIME := 3 x TC_INTERVAL

   o  A_HOLD_TIME := T_HOLD_TIME

19.4.  Received Message Validity Time Parameters

   o  RX_HOLD_TIME := 30 seconds

   o  P_HOLD_TIME := 30 seconds

   o  F_HOLD_TIME := 30 seconds

19.5.  Jitter Time Parameters

   o  TP_MAXJITTER := HP_MAXJITTER

   o  TT_MAXJITTER := HT_MAXJITTER

   o  F_MAXJITTER := TT_MAXJITTER

19.6.  Hop Limit Parameter

   o  TC_HOP_LIMIT := 255





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19.7.  Willingness Parameter and Constants

   o  WILLINGNESS := WILL_DEFAULT

   o  WILL_NEVER := 0

   o  WILL_DEFAULT := 7

   o  WILL_ALWAYS := 15

20.  Sequence Numbers

   Sequence numbers are used in this specification for 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 this protocol, the following MUST
   be observed when determining the ordering of sequence numbers.

   The term MAXVALUE designates in the following one more than the
   largest possible value for a sequence number.  For a 16 bit sequence
   number (as are those defined in this specification) MAXVALUE is
   65536.

   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

   When sequence numbers S1 and S2 differ by MAXVALUE/2 their ordering
   cannot be determined.  In this case, which should not occur, either
   ordering may be assumed.

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

21.  Extensions

   An extension to this protocol will need to interact with this
   specification, and possibly also with [NHDP].  This protocol is
   designed to permit such interactions, in particular:

   o  Through accessing, and possibly extending, the information in the
      Information Bases.  All updates to the elements specified in this



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      document are subject to the constraints specified in [NHDP] and
      Appendix D.

   o  Through accessing an outgoing message prior to it being
      transmitted over any OLSRv2 interface, and to add information to
      it as specified in [RFC5444].  This MAY include Message TLVs
      and/or network addresses with associated Address Block TLVs.
      (Network addresses without new associated TLVs SHOULD NOT be added
      to messages.)  This may, for example, be to allow a security
      protocol, as suggested in Section 22, to add a TLV containing a
      cryptographic signature to the message.

   o  Through accessing an incoming message, and potentially discarding
      it prior to processing by this protocol.  This may, for example,
      allow a security protocol as suggested in Section 22 to perform
      verification of message signatures and prevent processing and/or
      forwarding of unverifiable messages by this protocol.

   o  Through accessing an incoming message after it has been completely
      processed by this protocol.  This may, in particular, allow a
      protocol which has added information, by way of inclusion of
      appropriate TLVs, or of network addresses associated with new
      TLVs, access to such information after appropriate updates have
      been recorded in the Information Bases in this protocol.

   o  Through requesting that a message be generated at a specific time.
      In that case, message generation MUST still respect the
      constraints in [NHDP] and Section 5.4.

22.  Security Considerations

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

22.1.  Confidentiality

   This protocol periodically MPR floods topological information to all
   routers in the network.  Hence, if used in an unprotected wireless
   network, the network topology is revealed to anyone who listens to
   the 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 [RFC4880] or
   encrypted by some shared secret key, can be applied to ensure that
   control traffic can be read and interpreted by only those authorized



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   to do so.

22.2.  Integrity

   Each router is injecting topological information into the network
   through transmitting HELLO messages and, for some routers, TC
   messages.  If some routers 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 router generates TC messages, advertising links to non-neighbor
       routers;

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

   3.  a router generates HELLO messages, advertising non-neighbor
       routers;

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

   5.  a router forwards altered control messages;

   6.  a router does not forward control messages;

   7.  a router does not select multipoint relays correctly;

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

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

   Authentication of the originator router 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 routers from repeating old (and
   correctly authenticated) information (situation 9) temporal
   information is required, allowing a router to positively identify
   such delayed messages.

   In general, digital signatures and other required security
   information may be transmitted as a separate Message Type, or
   signatures and security information may be transmitted within the
   HELLO and TC messages, using the TLV mechanism.  Either option
   permits that "secured" and "unsecured" routers can coexist in the



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   same network, if desired,

   Specifically, the authenticity of entire control packets 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 are
   transmitted either to all routers in the neighborhood (HELLO
   messages) or broadcast to all routers in the network (TC messages).

   For example, a control message in this protocol is always a point-to-
   multipoint transmission.  It is therefore important that the
   authentication mechanism employed permits that any receiving router
   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.

22.3.  Interaction with External Routing Domains

   This protocol does, through the use of TC messages, provide a basic
   mechanism for injecting external routing information to this
   protocol's domain.  Routing information can be extracted from the
   protocol's Information Bases, in particular the Routing Set, of this
   protocol and, potentially, injected into an external domain, if the
   routing protocol governing that domain permits this.

   When operating routers connecting a MANET using this protocol to an
   external routing domain, care MUST be taken not to allow potentially
   insecure and untrustworthy information to be injected from this
   domain to external routing domains.  Care MUST also be taken to
   validate the correctness of information prior to it being injected as
   to avoid polluting routing tables with invalid information.

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

23.  IANA Considerations

   This specification defines one Message Type, which must be allocated
   from the "Message Types" repository of [RFC5444], two Message TLV
   Types, which must be allocated from the "Message TLV Types"
   repository of [RFC5444], and three Address Block TLV Types, which
   must be allocated from the "Address Block TLV Types" repository of



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   [RFC5444].

23.1.  Expert Review: Evaluation Guidelines

   For the registries where an Expert Review is required, the designated
   expert SHOULD take the same general recommendations into
   consideration as are specified by [RFC5444].

23.2.  Message Types

   This specification defines one Message Type, to be allocated from the
   0-223 range of the "Message Types" namespace defined in [RFC5444], as
   specified in Table 6.

          +------+----------------------------------------------+
          | Type | Description                                  |
          +------+----------------------------------------------+
          | TBD1 | TC : Topology Control (MANET-wide signaling) |
          +------+----------------------------------------------+

                     Table 6: Message Type assignment

23.3.  Message-Type-specific TLV Type Registries

   IANA is requested to create a registry for Message-Type-specific
   Message TLVs for TC messages, in accordance with Section 6.2.1 of
   [RFC5444], and with initial assignments and allocation policies as
   specified in Table 7.

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

            Table 7: TC Message-Type-specific Message TLV Types

   IANA is requested to create a registry for Message-Type-specific
   Address Block TLVs for TC messages, in accordance with Section 6.2.1
   of [RFC5444], and with initial assignments and allocation policies as
   specified in Table 8.

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




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         Table 8: TC Message-Type-specific Address Block TLV Types

23.4.  Message TLV Types

   This specification defines two Message TLV Types, which must be
   allocated from the "Message TLV Types" namespace defined in
   [RFC5444].  IANA is requested to make allocations in the 0-127 range
   for these types.  This will create two new Type Extension registries
   with assignments as specified in Table 9 and Table 10.
   Specifications of these TLVs are in Section 14.2.1 and
   Section 15.2.1, respectively.  Each of these TLVs MUST NOT be
   included more than once in a Message TLV Block.

   +-------------+------+-----------+---------------------+------------+
   |     Name    | Type |    Type   | Description         | Allocation |
   |             |      | Extension |                     | Policy     |
   +-------------+------+-----------+---------------------+------------+
   | MPR_WILLING | TBD2 |     0     | Specifies the       |            |
   |             |      |           | originating         |            |
   |             |      |           | router's            |            |
   |             |      |           | willingness to act  |            |
   |             |      |           | as a relay and to   |            |
   |             |      |           | partake in network  |            |
   |             |      |           | formation (maximum  |            |
   |             |      |           | value is            |            |
   |             |      |           | WILL_ALWAYS = 15)   |            |
   | MPR_WILLING | TBD2 |   1-255   | Unassigned          | Expert     |
   |             |      |           |                     | Review     |
   +-------------+------+-----------+---------------------+------------+

             Table 9: Message TLV Type assignment: MPR_WILLING

   +--------------+------+-----------+--------------------+------------+
   |     Name     | Type |    Type   | Description        | Allocation |
   |              |      | Extension |                    | Policy     |
   +--------------+------+-----------+--------------------+------------+
   | CONT_SEQ_NUM | TBD3 |     0     | COMPLETE :         |            |
   |              |      |           | Specifies a        |            |
   |              |      |           | content sequence   |            |
   |              |      |           | number for this    |            |
   |              |      |           | complete message   |            |
   | CONT_SEQ_NUM | TBD3 |     1     | INCOMPLETE :       |            |
   |              |      |           | Specifies a        |            |
   |              |      |           | content sequence   |            |
   |              |      |           | number for this    |            |
   |              |      |           | incomplete message |            |





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   | CONT_SEQ_NUM | TBD3 |   2-255   | Unassigned         | Expert     |
   |              |      |           |                    | Review     |
   +--------------+------+-----------+--------------------+------------+

            Table 10: Message TLV Type assignment: CONT_SEQ_NUM

   Type extensions indicated as Expert Review SHOULD be allocated as
   described in [RFC5444], based on Expert Review as defined in
   [RFC5226].

23.5.  Address Block TLV Types

   This specification defines three Address Block TLV Types, which must
   be allocated from the "Address Block TLV Types" namespace defined in
   [RFC5444].  IANA are requested to make allocations in the 8-127 range
   for these types.  This will create three new Type Extension
   registries with assignments as specified in Table 11, Table 12 and
   Table 13, respectively.  Specifications of these TLVs are in
   Section 14.2.2 and Section 15.2.2.

   +------+------+-----------+----------------------------+------------+
   | Name | Type |    Type   | Description                | Allocation |
   |      |      | Extension |                            | Policy     |
   +------+------+-----------+----------------------------+------------+
   |  MPR | TBD4 |     0     | Specifies that a given     |            |
   |      |      |           | network address is of a    |            |
   |      |      |           | router selected as an MPR  |            |
   |  MPR | TBD4 |   1-255   | Unassigned                 | Expert     |
   |      |      |           |                            | Review     |
   +------+------+-----------+----------------------------+------------+

             Table 11: Address Block TLV Type assignment: MPR



















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   +---------------+------+-----------+-------------------+------------+
   |      Name     | Type |    Type   | Description       | Allocation |
   |               |      | Extension |                   | Policy     |
   +---------------+------+-----------+-------------------+------------+
   | NBR_ADDR_TYPE | TBD5 |     0     | Specifies that a  |            |
   |               |      |           | given network     |            |
   |               |      |           | address is of a   |            |
   |               |      |           | neighbor reached  |            |
   |               |      |           | via the           |            |
   |               |      |           | originating       |            |
   |               |      |           | router, if it is  |            |
   |               |      |           | an originator     |            |
   |               |      |           | address           |            |
   |               |      |           | (ORIGINATOR = 1), |            |
   |               |      |           | is a routable     |            |
   |               |      |           | address (ROUTABLE |            |
   |               |      |           | = 2), or if it is |            |
   |               |      |           | both              |            |
   |               |      |           | (ROUTABLE_ORIG =  |            |
   |               |      |           | 3)                |            |
   | NBR_ADDR_TYPE | TBD5 |   1-255   | Unassigned        | Expert     |
   |               |      |           |                   | Review     |
   +---------------+------+-----------+-------------------+------------+

        Table 12: Address Block TLV Type assignment: NBR_ADDR_TYPE

   +---------+------+-----------+-------------------------+------------+
   |   Name  | Type |    Type   | Description             | Allocation |
   |         |      | extension |                         | Policy     |
   +---------+------+-----------+-------------------------+------------+
   | GATEWAY | TBD6 |     0     | Specifies that a given  |            |
   |         |      |           | network address is      |            |
   |         |      |           | reached via a gateway   |            |
   |         |      |           | on the originating      |            |
   |         |      |           | router, with value      |            |
   |         |      |           | equal to the number of  |            |
   |         |      |           | hops                    |            |
   | GATEWAY | TBD6 |   1-255   |                         | Expert     |
   |         |      |           |                         | Review     |
   +---------+------+-----------+-------------------------+------------+

           Table 13: Address Block TLV Type assignment: GATEWAY

   Type extensions indicated as Expert Review SHOULD be allocated as
   described in [RFC5444], based on Expert Review as defined in
   [RFC5226].





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23.6.  NBR_ADDR_TYPE Values

   Note: This section does not require any IANA action, as the required
   information is included in the descriptions of the NBR_ADDR_TYPE
   Address Block TLV allocated in Section 23.5.  This information is
   recorded here for clarity, and for use elsewhere in this
   specification.

   The Values which the NBR_ADDR_TYPE Address Block TLV can use are the
   following:

   o  ORIGINATOR := 1;

   o  ROUTABLE := 2;

   o  ROUTABLE_ORIG := 3.

24.  Contributors

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

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

   o  Emmanuel Baccelli, INRIA , France, <Emmanuel.Baccelli@inria.fr>

   o  Thomas Heide Clausen, LIX, 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, <hiroki.satoh.yj@hitachi.com>

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

   o  Monden Kazuya, Hitachi SDL, Japan, <kazuya.monden.vw@hitachi.com>

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

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

25.  Acknowledgments

   The authors would like to acknowledge the team behind OLSRv1,
   specified in RFC3626, including Anis Laouiti (INT, Paris), Pascale
   Minet (INRIA, France), Laurent Viennot (INRIA, France), and Amir



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   Qayyum (M.A. Jinnah University, Islamabad) 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 (listed alphabetically): Khaldoun Al
   Agha (LRI), Teco Boot (Infinity Networks), Song-Yean Cho (LIX), Alan
   Cullen (BAE Systems), Louise Lamont (CRC), Li Li (CRC), Joe Macker
   (NRL), Richard Ogier (SRI), Charles E. Perkins (WiChorus), Henning
   Rogge (FGAN), and the entire IETF MANET working group.

26.  References

26.1.  Normative References

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

   [RFC5148]    Clausen, T., Dearlove, C., and B. Adamson, "Jitter
                considerations in MANETs", RFC 5148, February 2008.

   [RFC5226]    Narten, T. and H. Alvestrand, "Guidelines for Writing an
                IANA Considerations Section in RFCs", RFC 5226, BCP 26,
                May 2008.

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

   [RFC5497]    Clausen, T. and C. Dearlove, "Representing multi-value
                time in MANETs", RFC 5497, March 2009.

   [RFC5498]    Chakeres, I., "IANA Allocations for MANET Protocols",
                RFC 5498, March 2009.

   [NHDP]       Clausen, T., Dean, J., and C. Dearlove, "MANET
                Neighborhood Discovery Protocol (NHDP)", work in
                progress draft-ietf-manet-nhdp-12.txt, March 2010.

26.2.  Informative References

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

   [RFC3626]    Clausen, T. and P. Jacquet, "The Optimized Link State
                Routing Protocol", RFC 3626, October 2003.

   [RFC4880]    Callas, J., Donnerhacke, L., Finney, H., and R. Thayer,



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                "OpenPGP message format", RFC 4880, November 2007.

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

   [HIPERLAN2]  Jacquet, P., Minet, P., Muhlethaler, P., and N.
                Rivierre, "Increasing reliability in cable free radio
                LANs: Low level forwarding in HIPERLAN.", 1996.

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

   [FSR]        Pei, G., Gerla, M., and T. Chen, "Fisheye state routing
                in mobile ad hoc networks", 2000.

   [FSLS]       Santivanez, C., Ramanathan, R., and I. Stavrakakis,
                "Making link-state routing scale for ad hoc networks",
                2000.

Appendix A.  Example Algorithm for Calculating MPRs

   The following specifies an algorithm which MAY be used to select
   MPRs.  MPRs are calculated per OLSRv2 interface, but then a single
   set of MPRs is formed from the union of the MPRs for all OLSRv2
   interfaces.  (As noted in Section 17 a router MAY improve on this, by
   coordination between OLSRv2 interfaces.)  A router's MPRs are
   recorded using the element N_mpr in Neighbor Tuples.

   If using this example algorithm then the following steps MUST be
   executed in order for a router to select its MPRs:

   1.  Set N_mpr := false in all Neighbor Tuples;

   2.  For each Neighbor Tuple with N_symmetric = true and N_willingness
       = WILL_ALWAYS, set N_mpr := true;

   3.  For each OLSRv2 interface of the router, use the algorithm in
       Appendix A.2.  Note that this sets N_mpr := true for some
       Neighbor Tuples, these routers are already selected as MPRs when
       using the algorithm for following OLSRv2 interfaces.

   4.  OPTIONALLY, consider each selected MPR in turn, and if the set of
       selected MPRs without that router still satisfies the necessary
       conditions, for all OLSRv2 interfaces, then that router MAY be
       removed from the set of MPRs.  This process MAY be repeated until
       no MPRs are removed.  Routers MAY be considered in order of



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       increasing N_willingness.

   Note that only symmetric strict 2-hop neighbors are considered, thus:

   o  Symmetric 1-hop neighbor routers with N_willingness = WILL_NEVER
      MUST NOT be selected as MPRs, and MUST be ignored in the following
      algorithm (and hence also ignore any 2-Hop Tuples whose
      N2_neighbor_iface_addr_list is included in the
      N_neighbor_addr_list of any such Neighbor Tuple).

   o  Symmetric 2-hop neighbor routers which are also symmetric 1-hop
      neighbor routers MUST be ignored in the following algorithm (i.e.,
      ignore any 2-Hop Tuples whose N2_2hop_addr is in the
      N_neighbor_addr_list of any Neighbor Tuple).

A.1.  Terminology

   The following terminology will be used when selecting MPRs for the
   OLSRv2 interface I:

   N(I)  - The set of symmetric 1-hop neighbors which have a symmetric
      link to I.

   N2(I)  - The set of network addresses of interfaces of a router with
      a symmetric link to a router in N(I); this MAY be restricted to
      considering only information received over I (in which case N2(I)
      is the set of N2_2hop_addr in 2-Hop Tuples in the 2-Hop Set for
      OLSRv2 interface I).

   Connected to I via Y  - A network address A in N2(I) is connected to
      I via a router Y in N(I) if A is a network address of an interface
      of a symmetric 1-hop neighbor of Y (i.e., A is the N2_2hop_addr in
      a 2-Hop Tuple in the 2-Hop Set for OLSRv2 interface I, and whose
      N2_neighbor_iface_addr_list is contained in the set of interface
      network addresses of Y).

   D(Y, I)  - For a router Y in N(I), the number of network addresses in
      N2(I) which are connected to I via Y.

   R(Y, I):  - For a router Y in N(I), the number of network addresses
      in N2(I) which are connected to I via Y, but are not connected to
      I via any router which has already been selected as an MPR.

A.2.  MPR Selection Algorithm for each OLSRv2 Interface

   When selecting MPRs for the OLSRv2 interface I:





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   1.  For each network address A in N2(I) for which there is only one
       router Y in N(I) such that A is connected to I via Y, select that
       router Y as an MPR (i.e., set N_mpr := true in the Neighbor Tuple
       corresponding to Y).

   2.  While there exists any router Y in N(I) with R(Y, I) > 0:

       1.  Select a router Y in N(I) with R(Y, I) > 0 in the following
           order of priority:

           +  greatest N_willingness in the Neighbor Tuple corresponding
              to Y, THEN;

           +  greatest R(Y, I), THEN;

           +  greatest D(Y, I), THEN;

           +  N_mpr_selector is equal to true, if possible, THEN;

           +  any choice.

       2.  Select Y as an MPR (i.e., set N_mpr := true in the Neighbor
           Tuple corresponding to Y).

Appendix B.  Example Algorithm for Calculating the Routing Set

   The following procedure is given as an example for calculating the
   Routing Set using a variation of Dijkstra's algorithm.  First all
   Routing Tuples are removed, and then, using the selections and
   definitions in Appendix B.1, the procedures in the following sections
   (each considered a "stage" of the processing) are applied in turn.

B.1.  Local Interfaces and Neighbors

   The following selections and definitions are made:

   1.  For each Local Interface Tuple, select a network address from its
       I_local_iface_addr_list, this is defined as the selected address
       for this Local Interface Tuple.

   2.  For each Link Tuple, the selected address of its corresponding
       Local Interface Tuple is defined as the selected local address
       for this Local Interface Tuple.

   3.  For each Neighbor Tuple with N_symmetric = true, the selected
       local address is defined as the selected local address of the
       selected Link Tuple for that Neighbor Tuple.




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   4.  For each network address (N_orig_addr or in N_neighbor_addr_list,
       the "neighbor address") from a Neighbor Tuple with N_symmetric =
       true, select a Link Tuple with L_status = SYMMETRIC whose
       corresponding Neighbor Tuple is this Neighbor Tuple and where, if
       possible, L_neighbor_iface_addr_list contains the neighbor
       address.  This is defined as the selected Link Tuple for that
       neighbor address.

   5.  For each network address (N_orig_addr or in N_neighbor_addr_list,
       the "neighbor address") from a Neighbor Tuple with N_symmetric =
       true, a selected address from the L_neighbor_iface_addr_list of
       the selected Link Tuple for the neighbor address, if possible
       equal to the neighbor address, is defined as the selected link
       address for that neighbor address.

   6.  Routing Tuple preference is decided by preference for
       corresponding Neighbor Tuples in this order:

       *  For greater N_willingness.

       *  For N_mpr_selector = true over N_mpr_selector = false.

B.2.  Add Neighbor Routers

   The following procedure is executed once.

   1.  For each Neighbor Tuple with N_symmetric = true, add a Routing
       Tuple with:

       *  R_dest_addr := N_orig_addr;

       *  R_next_iface_addr := selected link address;

       *  R_local_iface_addr := selected local address;

       *  R_dist := 1.

B.3.  Add Remote Routers

   The following procedure is executed for each value of h, starting
   with h := 1 and incrementing by 1 for each iteration.  The execution
   MUST stop if no new Routing Tuples are added in an iteration.

   1.  For each Router Topology Tuple, if:

       *  TR_to_orig_addr is not equal to the R_dest_addr of any Routing
          Tuple added in an earlier stage, AND;




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       *  TR_from_orig_addr is equal to the R_dest_addr of a Routing
          Tuple with R_dist = h (the "previous Routing Tuple"),

       then add a new Routing Tuple, with:

       *  R_dest_addr := TR_to_orig_addr;

       *  R_next_iface_addr := R_next_iface_addr of the previous Routing
          Tuple;

       *  R_local_iface_addr := R_local_iface_addr of the previous
          Routing Tuple;

       *  R_dist := h+1.

       There may be more than one possible Routing Tuple that may be
       added for an R_dest_addr in this stage.  If so, then, for each
       such R_dest_addr, a Routing Tuple which is preferred SHOULD be
       added.

B.4.  Add Neighbor Addresses

   The following procedure is executed once.

   1.  For each Neighbor Tuple with N_symmetric = true:

       1.  For each network address (the "current address") in
           N_neighbor_addr_list, if the current address is not equal to
           the R_dest_addr of any Routing Tuple, then add a new Routing
           Tuple, with:

           +  R_dest_addr := current address;

           +  R_next_iface_addr := selected link address;

           +  R_local_iface_addr := selected local address;

           +  R_dist := 1.

B.5.  Add Remote Routable Addresses

   The following procedure is executed once.

   1.  For each Routable Address Topology Tuple, if:

       *  TA_dest_addr is not equal to the R_dest_addr of any Routing
          Tuple added in an earlier stage, AND;




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       *  TR_from_orig_addr is equal to the R_dest_addr of a Routing
          Tuple (the "previous Routing Tuple"),

       then add a new Routing Tuple, with:

       *  R_dest_addr := TA_dest_addr;

       *  R_next_iface_addr := R_next_iface_addr of the previous Routing
          Tuple;

       *  R_local_iface_addr := R_local_iface_addr of the previous
          Routing Tuple;

       *  R_dist := R_dist of the previous Routing Tuple + 1.

       There may be more than one possible Routing Tuple that may be
       added for an R_dest_addr in this stage.  If so, then, for each
       such R_dest_addr, a Routing Tuple which is preferred SHOULD be
       added.

B.6.  Add Attached Networks

   The following procedure is executed once.

   1.  For each Attached Network Tuple, if:

       *  AN_net_addr is not equal to the R_dest_addr of any Routing
          Tuple added in an earlier stage, AND;

       *  AN_orig_addr is equal to the R_dest_addr of a Routing Tuple
          (the "previous Routing Tuple),

       then add a new Routing Tuple, with:

       *  R_dest_addr := AN_net_addr;

       *  R_next_iface_addr := R_next_iface_addr of the previous Routing
          Tuple;

       *  R_local_iface_addr := R_local_iface_addr of the previous
          Routing Tuple;

       *  R_dist := R_dist of the previous Routing Tuple + AN_dist.

       There may be more than one possible Routing Tuple that may be
       added for an R_dest_addr in this stage.  If so, then, for each
       such R_dest_addr, a Routing Tuple with minimum R_dist MUST be
       selected, otherwise a Routing Tuple which is preferred SHOULD be



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       added.

B.7.  Add 2-Hop Neighbors

   The following procedure is executed once.

   1.  For each 2-Hop Tuple, if:

       *  N2_2hop_addr is a routable address, AND;

       *  N2_2hop_addr is not equal to the R_dest_addr of any Routing
          Tuple added in an earlier stage,

       then define the "previous Routing Tuple" as that with R_dest_addr
       = N_orig_addr of the corresponding Neighbor Tuple, and add a new
       Routing Tuple, with:

       *  R_dest_addr := N2_2hop_addr;

       *  R_next_iface_addr := R_next_iface_addr of the previous Routing
          Tuple;

       *  R_local_iface_addr := R_local_iface_addr of the previous
          Routing Tuple;

       *  R_dist := 2.

       There may be more than one possible Routing Tuple that may be
       added for an R_dest_addr in this stage.  If so, then, for each
       such R_dest_addr, a Routing Tuple which is preferred SHOULD be
       added.

Appendix C.  TC Message Example

   TC messages are instances of [RFC5444] messages.  This protocol
   requires that TC messages contains <msg-hop-limit> and <msg-orig-
   addr> fields.  It supports TC messages with any combination of
   remaining message header options and address encodings, enabled by
   [RFC5444] that convey the required information.  As a consequence,
   there is no single way to represent how all TC messages look.  This
   appendix illustrates a TC message, the exact values and content
   included are explained in the following text.

   The message has full Message Header (four bit Flags field value is
   15).  Its four bit Message Address Length field has value 3 and hence
   addresses in the message have length four octets, here being IPv4
   addresses.  The overall message length is 57 octets.




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   The message has a Message TLV Block with content length 13 octets
   containing three TLVs.  The first two TLVs are interval and validity
   times for the message.  The third TLV is the content sequence number
   TLV used to carry the 2 octet ANSN, and (with default type extension
   zero, i.e., COMPLETE) indicating that the TC message is complete.
   Each TLV uses a TLV with Flags octet value 16, indicating that it has
   a Value, but no type extension or start and stop indexes.  The first
   two TLVs have a Value Length of 1 octet, the last has a Value Length
   of 2 octets.

   The message has two Address Blocks.  (This is not necessary, the
   information could be conveyed using a single Address Block, the use
   of two Address Blocks, which is also allowed, is illustrative only.)
   The first Address Block contains 3 addresses, with Flags octet value
   128, hence with a Head section, (with length 2 octets) but no Tail
   section, and hence Mid sections with length two octets.  The
   following TLV Block (content length 6 octets) contains a single
   NBR_ADDR_TYPE TLV (Flags octet value 16, includes a Value but no
   indexes) indicating that these addresses are associated with the
   Value (with Value Length 1 octet) ROUTABLE_ORIG, i.e., they are
   originator addresses of advertised neighbors that are also routable
   addresses.

   The second Address Block contains 1 address, with Flags octet 176
   indicating that there is a Head section (with length 2 octets), that
   the Tail section (length 2 octets) consists of zero valued octets
   (not included), and that there is a single prefix length, which is
   16.  The network address is thus Head.0.0/16.  The following TLV
   Block (content length 8 octets) includes one TLV that indicates that
   the originating router is a gateway to this network, at a given
   number of hops distance (Value Length 1 octet).  The TLV Flags octet
   value of 16 again indicates that a Value, but no indexes are needed.



















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      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       |1 1 1 1 0 0 1 1|0 0 0 0 0 0 0 0 0 0 1 1 1 0 0 1|
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                      Originator Address                       |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |   Hop Limit   |   Hop Count   |    Message Sequence Number    |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 1| INTERVAL_TIME |0 0 0 1 0 0 0 0|
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |0 0 0 0 0 0 0 1|     Value     | VALIDITY_TIME |0 0 0 1 0 0 0 0|
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |0 0 0 0 0 0 0 1|     Value     | CONT_SEQ_NUM  |0 0 0 1 0 0 0 0|
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |0 0 0 0 0 0 1 0|         Value (ANSN)          |0 0 0 0 0 0 1 1|
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |1 0 0 0 0 0 0 0|0 0 0 0 0 0 1 0|             Head              |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |              Mid              |              Mid              |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |              Mid              |0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0|
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     | NBR_ADDR_TYPE |0 0 0 1 0 0 0 0|0 0 0 0 0 0 0 1| ROUTABLE_ORIG |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |0 0 0 0 0 0 0 1|1 0 1 1 0 0 0 0|0 0 0 0 0 0 1 0|     Head      |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Head (cont)  |0 0 0 0 0 0 1 0|0 0 0 1 0 0 0 0|0 0 0 0 0 0 0 0|
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |0 0 0 0 0 1 0 0|    GATEWAY    |0 0 0 1 0 0 0 0|0 0 0 0 0 0 0 1|
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Number Hops  |
     +-+-+-+-+-+-+-+-+

Appendix D.  Constraints

   Any process which updates the Local Information Base, the
   Neighborhood Information Base or the Topology Information Base MUST
   ensure that all constraints specified in this appendix are
   maintained, as well as those specified in [NHDP].

   In each Originator Tuple:

   o  O_orig_addr MUST NOT equal any other O_orig_addr.

   o  O_orig_addr MUST NOT equal this router's originator address.

   In each Local Attached Network Tuple:



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   o  AL_net_addr MUST NOT equal any other AL_net_addr.

   o  AL_net_addr MUST NOT equal or be a sub-range of any network
      address in the I_local_iface_addr_list of any Local Interface
      Tuple.

   o  AL_net_addr MUST NOT equal this router's originator address, or
      equal the O_orig_addr in any Originator Tuple.

   o  AL_dist MUST NOT be less than zero.

   In each Link Tuple:

   o  L_neighbor_iface_addr_list MUST NOT contain any network address
      that AL_net_addr of any Local Attached Network Tuple equals or is
      a sub-range of.

   In each Neighbor Tuple:

   o  N_orig_addr MUST NOT be changed to unknown.

   o  N_orig_addr MUST NOT equal this router's originator address, or
      equal O_orig_addr in any Originator Tuple.

   o  N_orig_addr MUST NOT equal the AL_net_addr in any Local Attached
      Network Tuple.

   o  If N_orig_addr != unknown, then N_orig_addr MUST NOT equal the
      N_orig_addr in any other Neighbor Tuple.

   o  N_neighbor_addr_list MUST NOT contain any network address which
      includes this router's originator address, the O_orig_addr in any
      Originator Tuple, or equal or have as a sub-range the AL_net_addr
      in any Local Attached Network Tuple.

   o  If N_orig_addr = unknown, then N_willingness = WILL_NEVER, N_mpr =
      false, N_mpr_selector = false, and N_advertised = false.

   o  N_willingness MUST be in the range from WILL_NEVER to WILL_ALWAYS,
      inclusive.

   o  If N_mpr = true, then N_symmetric MUST be true and N_willingness
      MUST NOT equal WILL_NEVER.

   o  If N_symmetric = true and N_mpr = false, then N_willingness MUST
      NOT equal WILL_ALWAYS.





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   o  If N_mpr_selector = true, then N_advertised MUST be true.

   o  If N_advertised = true, then N_symmetric MUST be true.

   In each Lost Neighbor Tuple:

   o  NL_neighbor_addr MUST NOT include this router's originator
      address, the O_orig_addr in any Originator Tuple, or equal or have
      as a sub-range the AL_net_addr in any Local Attached Network
      Tuple.

   In each 2-Hop Tuple:

   o  N2_2hop_addr MUST NOT equal this router's originator address,
      equal the O_orig_addr in any Originator Tuple, or equal or have as
      a sub-range the AL_net_addr in any Local Attached Network Tuple

   In each Advertising Remote Router Tuple:

   o  AR_orig_addr MUST NOT be in any network address in the
      I_local_iface_addr_list in any Local Interface Tuple or be in the
      IR_local_iface_addr in any Removed Interface Address Tuple.

   o  AR_orig_addr MUST NOT equal this router's originator address or
      equal the O_orig_addr in any Originator Tuple.

   o  AR_orig_addr MUST NOT be in the AL_net_addr in any Local Attached
      Network Tuple.

   o  AR_orig_addr MUST NOT equal the AR_orig_addr in any other
      Advertising Remote Router Tuple.

   In each Router Topology Tuple:

   o  There MUST be an Advertising Remote Router Tuple with AR_orig_addr
      = TR_from_orig_addr.

   o  TR_to_orig_addr MUST NOT be in any network address in the
      I_local_iface_addr_list in any Local Interface Tuple or be in the
      IR_local_iface_addr in any Removed Interface Address Tuple.

   o  TR_to_orig_addr MUST NOT equal this router's originator address or
      equal the O_orig_addr in any Originator Tuple.

   o  TR_to_orig_addr MUST NOT be in the AL_net_addr in any Local
      Attached Network Tuple.





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   o  The ordered pair (TR_from_orig_addr, TR_to_orig_addr) MUST NOT
      equal the corresponding pair for any other Router Topology Tuple.

   o  TR_seq_number MUST NOT be greater than AR_seq_number in the
      Advertising Remote Router Tuple with AR_orig_addr =
      TR_from_orig_addr.

   In each Routable Address Topology Tuple:

   o  There MUST be an Advertising Remote Router Tuple with AR_orig_addr
      = TA_from_orig_addr.

   o  TA_dest_addr MUST be routable.

   o  TA_dest_addr MUST NOT overlap any network address in the
      I_local_iface_addr_list in any Local Interface Tuple or overlap
      the IR_local_iface_addr in any Removed Interface Address Tuple.

   o  TA_dest_addr MUST NOT include this router's originator address or
      include the O_orig_addr in any Originator Tuple.

   o  TA_dest_addr MUST NOT equal or have as a sub-range the AL_net_addr
      in any Local Attached Network Tuple.

   o  The ordered pair (TA_from_orig_addr, TA_dest_addr) MUST NOT equal
      the corresponding pair for any other Attached Network Tuple.

   o  TA_seq_number MUST NOT be greater than AR_seq_number in the
      Advertising Remote Router Tuple with AR_orig_addr =
      TA_from_orig_addr.

   In each Attached Network Tuple:

   o  There MUST be an Advertising Remote Router Tuple with AR_orig_addr
      = AN_orig_addr.

   o  AN_net_addr MUST NOT equal or be a sub-range of any network
      address in the I_local_iface_addr_list in any Local Interface
      Tuple or be a sub-range of the IR_local_iface_addr in any Removed
      Interface Address Tuple.

   o  AN_net_addr MUST NOT equal this router's originator address or
      equal the O_orig_addr in any Originator Tuple.

   o  AN_net_addr MUST NOT equal the AL_net_addr in any Local Attached
      Network Tuple.





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   o  The ordered pair (AN_orig_addr, AN_net_addr) MUST NOT equal the
      corresponding pair for any other Attached Network Tuple.

   o  AN_seq_number MUST NOT be greater than AR_seq_number in the
      Advertising Remote Router Tuple with AR_orig_addr = AN_orig_addr.

   o  AN_dist MUST NOT be less than zero.

Appendix E.  Flow and Congestion Control

   Due to its proactive nature, this protocol has a natural control over
   the flow of its control traffic.  Routers transmit control messages
   at predetermined rates specified and bounded by message intervals.

   This protocol employs [NHDP] for local signaling, embedding MPR
   selection advertisement through a simple Address Block TLV, and
   router willingness advertisement (if any) as a single Message TLV.
   Local signaling, therefore, shares the characteristics and
   constraints of [NHDP].

   Furthermore, the use of MPRs can greatly reduce the signaling
   overhead from link state information dissemination in two ways,
   attaining both flooding reduction and topology reduction.  First,
   using MPR flooding, the cost of distributing link state information
   throughout the network is reduced, as compared to when using classic
   flooding, since only MPRs need to forward link state declaration
   messages.  Second, the amount of link state information for a router
   to declare is reduced to need only contain that router's MPR
   selectors.  This reduces the size of a link state declaration as
   compared to declaring full link state information.  In particular
   some routers may not need to declare any such information.  In dense
   networks, the reduction of control traffic can be of several orders
   of magnitude compared to routing protocols using classical flooding
   [MPR].  This feature naturally provides more bandwidth for useful
   data traffic and pushes further the frontier of congestion.

   Since the control traffic is continuous and periodic, it keeps the
   quality of the links used in routing more stable.  However, using
   some options, some control messages (HELLO messages or TC messages)
   may be intentionally sent in advance of their deadline in order to
   increase the responsiveness of the protocol to topology changes.
   This may cause a small, temporary, and local increase of control
   traffic, however this is at all times bounded by the use of minimum
   message intervals.







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Authors' Addresses

   Thomas Heide Clausen
   LIX, Ecole Polytechnique

   Phone: +33 6 6058 9349
   EMail: T.Clausen@computer.org
   URI:   http://www.ThomasClausen.org/


   Christopher Dearlove
   BAE Systems ATC

   Phone: +44 1245 242194
   EMail: chris.dearlove@baesystems.com
   URI:   http://www.baesystems.com/


   Philippe Jacquet
   Project Hipercom, INRIA

   Phone: +33 1 3963 5263
   EMail: philippe.jacquet@inria.fr


   The OLSRv2 Design Team
   MANET Working Group
























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