Mobile Ad Hoc Networking Working Group                Charles E. Perkins
INTERNET DRAFT                             Sun Microsystems
10 August Laboratories
20 November 1998                                      Elizabeth M. Royer
                                 University of California, Santa Barbara

            Ad Hoc On Demand Distance Vector (AODV) Routing
                      draft-ietf-manet-aodv-01.txt
                      draft-ietf-manet-aodv-02.txt

Status of This Memo

   This document is a submission by the Mobile Ad Hoc Networking Working
   Group of the Internet Engineering Task Force (IETF).  Comments should
   be submitted to the manet@itd.nrl.navy.mil mailing list.

   Distribution of this memo is unlimited.

   This document is an Internet-Draft.  Internet-Drafts are working
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Abstract

   The Ad Hoc On-Demand Distance Vector (AODV) routing protocol is
   intended for use by mobile nodes in an ad hoc network characterized
   by frequent changes in link connectivity to each other caused
   by relative movement.  It offers quick adaptation to dynamic
   link conditions, low processing and memory overhead, low network
   utilization, and establishment of both unicast and multicast routes
   between sources and destinations which are loop free at all times.
   It makes use of destination sequence numbers, which are a novel means
   of ensuring loop freedom even in the face of anomalous delivery of
   routing control messages, and which solve solving classical problems associated
   with distance vector protocols, including the problem of
   "counting ``counting
   to infinity". infinity''.

                                Contents

Status of This Memo                                                    i

Abstract                                                               i

 1. Introduction                                                       2                                                       1

 2. Overview                                                           2                                                           1

 3. AODV Terminology                                                   4                                                   3

 4. Route Request (RREQ) Message Format                                       6                                5

 5. Route Reply (RREP) Message Format                                         8                                  6

 6. Multicast Route Invalidation Message Format                       10

 7. Node Operation - Unicast                                          11
     7.1.                                           7
     6.1. Maintaining Route Utilization Records . . . . . . . . . .   11
     7.2.    7
     6.2. Generating Route Requests (RREQs) . . . . . . . . . . . . . . . .   11
     7.3.    8
     6.3. Forwarding Route Requests . . . . . . . . . . . . . . . .   12
     7.4.    8
     6.4. Generating Route Replies (RREPs)  . . . . . . . . . . . . . . . .   13
     7.5. Generating Hello Messages . . .    9
     6.5. Maintaining Local Connectivity  . . . . . . . . . . . . .   13
     7.6.   10
     6.6. Initiating Triggered Route Replies (Triggered RREPs)  . . . . . . . . . . .   14
     7.7. Detecting Link Breakage . . . . . . . . . . . . . . . . .   15   11

 7. Multicast Route Activation (MACT) Message Format                  12

 8. Node Operation - Multicast                                        15                                        13
     8.1. Maintaining Multicast Tree Utilization Records  . . . . .   15   13
     8.2. Generating Multicast Route Requests RREQs  . . . . . . . . . . .   15 . . . .   13
     8.3. Forwarding Multicast Route Requests . . . . . . . . . . .   17   14
     8.4. Generating Multicast Route Replies  . . . . . . . . . . .   17   14
     8.5. Forwarding Route Replies  . . . . . . . . . . . . . . . .   15
     8.6. Route Deletion and Multicast Tree Pruning . . . . . . . .   18
     8.6.   16
     8.7. Repairing Link Breakages  . . . . . . . . . . . . . . . .   20
     8.7.   17
     8.8. Initiating Triggered Route Replies  . . . . . . . . . . .   22   19

 9. Configuration Parameters                                          22 Quality of Service                                                20

10. AODV and Aggregated Networks                                      20

11. Using AODV with Other Networks                                    21

12. Extensions                                                        21
    12.1. Hello Interval Extension Format . . . . . . . . . . . . .   22
    12.2. Multicast Group Leader Extension Format . . . . . . . . .   22
    12.3. Multicast Group Information Extension Format  . . . . . .   23
    12.4. Maximum Delay Extension Format  . . . . . . . . . . . . .   24

11.
    12.5. Minimum Bandwidth Extension Format  . . . . . . . . . . .   24

13. Configuration Parameters                                          25

14. Security Considerations                                           24                                           26

1. Introduction

   The Ad-Hoc Ad Hoc On-Demand Distance Vector (AODV) algorithm enables
   dynamic, self-starting, multihop routing between participating mobile
   nodes wishing to establish and maintain an ad-hoc ad hoc network.  AODV
   allows mobile nodes to obtain routes quickly for new destinations,
   and does not require nodes to maintain routes to destinations that
   are not in active communication.  Additionally, AODV allows for the
   formation of multicast groups whose membership is free to change
   during the lifetime of the network.  AODV also defines timely
   responses allows mobile nodes to
   respond quickly to link breakages and changes in network topology.
   The operation of AODV is loop free, and by avoiding the Bellman-Ford
   "counting
   ``counting to infinity" infinity'' problem offers quick convergence when the
   ad-hoc
   ad hoc network topology changes (typically, when a node moves in the
   network).

   One distinguishing feature of AODV is its use of a destination
   sequence number for each route entry.  The destination sequence
   number is created by the destination or the multicast grouphead group leader
   for any usable route information it sends to requesting nodes.  Using
   destination sequence numbers ensures loop freedom and is simple to
   program.  Given the choice between two routes to a destination, a
   requesting node always selects the one with the greatest sequence
   number.

   Another feature of AODV is that link breakages cause immediate
   notifications to be sent to the affected set of nodes, but only that
   set of nodes.

2. Overview

   Route Requests (RREQs), Route Replies (RREPs), and Multicast
   Route Invalidations (MINVs) Activations (MACTs) are the three message types defined by
   AODV. These message types are handled by UDP, and normal IP header
   processing applies.  So, for instance, the requesting node is
   expected to use its IP address as the source IP address for the
   messages.  The range of dissemination of broadcast RREQs can be
   indicated by the TTL in the IP header.  Fragmentation is typically
   not required.

   As long as the endpoints of a communication connection have valid
   routes to each other, AODV does not play any role.  When a route
   to a new destination (either a single node or a multicast group)
   is needed, the node uses a broadcast RREQ to find a route to the
   destination.  A route can be determined when the request RREQ reaches either
   the destination itself, or an intermediate node with a fresh enough
   route to the destination.  The route is made available by unicasting
   a RREP back to the source of the RREQ. Since each node receiving the
   request keeps track of caches a route back to the source of the request, the RREP
   can be unicast back from the destination to the source, or from any
   intermediate node that is able to satisfy the request back to the
   source.  In the multicast scenario,  RREQs are also used when a node wishes to join a multicast
   group.  A special join flag in the RREQ lets informs nodes know that when they receive receiving the
   RREP, they are not just setting route pointers but are actually
   grafting a branch on to the also setting
   multicast tree.

   If a RREP is broadcast to the limited broadcast address
   (255.255.255.255), and has a TTL of one, and a destination address
   of route pointers, which will be used if the node itself with metric 0, then it route is received by all selected
   to be added onto the
   node's neighbors, and treated by them as tree.

   In case AODV cannot rely on lower-level mechanisms for neighborhood
   determination, a "hello" message.  This
   hello special ``hello'' message is a local advertisement defined for use at the continued presence of
   the node.  Neighbors that are using routes through the broadcasting
   node will continue to mark the routes as valid.  If hello messages
   from
   network layer.

   For multicast groups, a particular node stop coming, the neighbor can assume that the
   node has moved away.  When that happens, the neighbor will mark the
   link to ``Group Hello'' message is broadcast across
   the node as broken, and may trigger a notification to some of
   its other neighbors that network by the link has broken.  Hello messages also
   carry multicast group leader.  The message carries
   multicast group and corresponding grouphead group leader IP addresses.  This
   information is used for repairing multicast trees after a previously
   disconnected portion of the network containing part of the multicast
   tree becomes reachable once again.

   Since AODV is a routing protocol, it deals with route table
   management.  AODV assumes the following fields exist in each route  Route table entry:

      - Destination IP Address
      - Destination Sequence Number
      - Hop Count
      - Next Hop
      - Lifetime

   This information must be kept even for ephemeral
   routes, such as are created to temporarily keep track of reverse
   paths towards nodes originating RREQs.  For multicast tree routes,  AODV assumes the following
   fields exist in each route table entry:

      - Destination IP Address
      - Destination Sequence Number
      - Hop Count
      - Next Hop field is
   likely to contain more than one entry.  For multicast tree routes,
   the
      - Lifetime
      - Routing Flags

   The following information is stored in each entry of the multicast
   route table: table for multicast tree routes:

      - Multicast Group IP Address
      - Multicast Grouphead Group Leader IP Address
      - Multicast Group Sequence Number
      - Hop Count to next Multicast Group member
      - Hop Count to Multicast Group leader
      - Next Hops
      - Lifetime
   Here the Hop Count corresponds to the distance in hops to the
   multicast grouphead.  Also, the

   The Next Hops field is a linked list of structures, each of which contain
   contains the fields:

      - Node IP Address
      - Active Flag

   The Active Flag indicates whether address of a neighbor in the link has actually been set, or
   whether an MINV messages multicast tree.

   The IP Address of a Next Hop is still pending only used to forward multicast
   messages after a MACT message has activated the route (see
   Section 8.5). 8.6).

3. AODV Terminology

   This protocol specification uses conventional meanings [1] for
   capitalized words such as MUST, SHOULD, etc., to indicate requirement
   levels for various protocol features.  This section defines other
   terminology used with AODV that is not already defined in [2].

      multicast grouphead

      forwarding node

         A node which agrees to forward packets destined for another
         destination node, by retransmitting them to a next hop which is
         closer to the destination along a path which has been set up
         using routing control messages.

      group leader

         A node which is a member of the given multicast group and which
         is the first such group member in the connected portion of
         the network.  This node is responsible for initializing and
         maintaining the multicast group destination sequence number.

      multicast tree

         The tree containing all nodes which are members of the
         multicast group and all nodes which are needed to connect the
         multicast group members.

      multicast route table

         The table were ad-hoc where ad hoc nodes keep routing (including next hops)
         information for various multicast groups.

      request table

         The table where ad-hoc ad hoc nodes keep information concerning the
         first node to request to join a multicast group.  There is one
         entry in the table for each multicast group for which the node
         has received a RREQ with the J `J' flag set (see Section 8.2.

      route table

         The table where ad-hoc nodes keep routing (including next hop)
         information for various destinations.  For IPv6, this can be
         associated with the Destination Cache.

      triggered update

         An unsolicited route update transmitted by an intermediate 8.2).

      subnet leader

         A node
         along which is a member of the path subnet defined by a specific
         routing prefix, and which offers reachability to every other
         node with the destination.

   This protocol specification uses conventional meanings [1] same routing prefix.  The subnet leader is
         responsible for
   capitalized words such as MUST, SHOULD, etc., to indicate requirement
   levels initializing and maintaining the destination
         sequence number for various protocol features. every node on the subnet.

4. Route Request (RREQ) Message Format

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |J|R|        Reserved           |   Hop Count   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          Broadcast ID                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Destination IP address                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Destination Sequence Number                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Source IP address                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Source Sequence Number                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The format of the Route Request message is illustrated above, and
   contains the following fields:

      Type           xx

      J              Join flag; set when source node wants to join a
                     multicast group.

      R              Repair flag; set when a node wants to initiate
                     a repair to connect two previously disconnected
                     portions of the multicast tree.

      Reserved       Sent as 0; ignored on reception.

      Hop Count      The number of hops from the Source IP Address to
                     the node handling the request.

      Broadcast ID   A sequence number uniquely identifying the
                     particular RREQ
                   uniquely when taken in conjunction with the
                     source node's IP address.

      Destination IP Address
                     The IP address of the destination for which a route
                     is desired.

      Destination Sequence Number
                     The last sequence number received in the past by
                     the source for any route towards the destination.

      Source IP Address
                     The IP address of the node which originated the
                     Route Request.

      Source Sequence Number
                     The current sequence number to be used for route information
                     entries pointing to (and generated by by) the source
                     of the route request.

   Extension:

   When a node wishes to repair a multicast tree, it appends the
   Multicast Group Leader extension (see Section 12.2).

5. Route Reply (RREP) Message Format

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |L|R|U| Reserved|  Prefix Size  |    Length   Hop Count   | Multicast Grouphead IP Addr...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ...Multicast Grouphead
   |                     Destination IP Addr address                    |   Multicast Group Hop Count
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Destination Sequence Number                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                           Lifetime                            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Type     xx

      Length
               The length of the extension field.

      Multicast Grouphead IP Address

   The IP Address of the Multicast Grouphead.  This
               extension is only used when a route to the Multicast
               Grouphead is known.

      Multicast Group Hop Count
               The distance in hops of the node sending the RREQ from
               the Multicast Grouphead.  This extension is only used for
               route rebuilding.

   This extension is included only when a route to the multicast
   grouphead is known.

5. Route Reply Message Format

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |L|          Reserved           |   Hop Count   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Destination IP address                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Destination Sequence Number                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                           Lifetime                            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The format format of the Route Reply message is illustrated above, and
   contains the following fields:

      Type          xx

      L             If the `L' bit is set, the message is a ``hello''
                    message and contains a list of the node's neighbors.

      R             Repair flag; set when a node wants to initiate
                    a repair to connect two previously disconnected
                    portions of the multicast tree.

      U             Update flag; set in a Group Hello, when the group
                    leader information has changed.

      Reserved      Sent as 0; ignored on reception.

      Prefix Size   If nonzero, the Prefix Size specifies that the
                    indicated route vector may be used for any nodes
                    with the same routing prefix (as defined by the
                    Prefix Size) as the requested destination.

      Hop Count     The number of hops from the Source IP Address to
                    the Destination IP Address.  For multicast route
                    requests this indicates the number of hops to the
                    multicast
                  grouphead.

      L           If the 'L' bit is set, the message is a "hello"
                  message and contains a list of the node's neighbors. group leader.

      Destination IP Address
                    The IP address of the destination for which a route
                    is supplied.

      Destination Sequence Number
                    The destination sequence number associated to the
                    route.

      Lifetime      The time for which nodes receiving the RREP consider
                    the route to be valid.

   Extension:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |    Length     |  Multicast Group IP Address ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ... Multicast Group IP Address  | Multicast Grouphead IP Addr ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ... Multicast Grouphead IP Addr |  Multicast Group Seq Number ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ... Multicast Group Seq Number  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Type     xx

      Length
               The length of the extension field.

      Multicast Group IP Address
               The IP Address of

   When the Multicast Group.

      Multicast Grouphead IP Address
               The IP Address of RREP is sent for a multicast destination, the Multicast Grouphead.

      Multicast
   Group Sequence Number
               The current sequence number of the Multicast Group.

   This Information extension is included when responding appended (see Section 12.3).

   Note that the Prefix Size allows a Subnet Leader to supply a multicast group route
   request.

6. Multicast Route Invalidation Message Format

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |            Reserved           |   Hop Count   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Destination IP address                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Destination Sequence Number                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Source
   for every host in the subnet defined by the routing prefix, which
   is determined by the IP address                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Source Sequence Number                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The format of the Multicast Route Invalidation message is illustrated
   above, Subnet Leader and contains the following fields:

      Type     xx

      Reserved
               Sent as 0; ignored on reception.

      Hop Count
               The number Prefix
   Size.  In order to make use of hops from this feature, the Source IP Address Subnet Leader has to
   guarantee reachability to all the
               Destination IP Address.

      Destination IP Address
               The IP address of hosts sharing the Multicast Group for which a route indicated subnet
   prefix.  The Subnet Leader is supplied. also responsible for maintaining the
   Destination Sequence Number
               The destination sequence number associated to for the
               Multicast Group.

      Source IP Address
               The IP address of the node which originated the Route
               Request.

      Source Sequence Number
               The current sequence number for route information
               generated by the source of the route request.

   Extensions:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |    Length     |      Next Hop IP Address...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       ...Next Hop IP Address      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Type     xx

      Length
               The length of the extension field

      Next Hop IP Address
               The IP address of the node chosen to be the next hop for
               the multicast tree.

   This extension is included when a source node wishes to invalidate
   all but one of the routes set up by RREPs.  It is not included when a
   multicast tree member is pruning itself from the tree.

7. whole subnet.

6. Node Operation - Unicast

   This section describes the scenarios under which nodes generate
   RREQs and RREPs for unicast communication, and how the fields in the
   message are handled.

7.1.

6.1. Maintaining Route Utilization Records

   For each valid route maintained by a node (containing a finite
   metric), the node also maintains a list of those neighbors that
   are actively using the route.  This active-list of neighbors will
   receive notifications from the node in the event of detection of a
   link breakage.

7.2.  A neighbor is on the active list if it has sent any
   packet to the node to be forwarded to the destination within the last
   ACTIVE_ROUTE_TIMEOUT milliseconds.

6.2. Generating Route Requests (RREQs)

   A node broadcasts a RREQ when it determines that it needs a route to
   a destination and does not have one available.  This can happen if
   the destination is previously unknown to the node, or if a previously
   valid route to the destination expires.  Routes can become invalid
   if they time out (the Lifetime associated with the route expires), expires or else if a link breakage results in is broken (i.e., an
   infinite metric being is associated with the route. route).  When a route table
   entry is marked with an infinite metric, its expiration time is also
   updated to be the current time plus BAD_LINK_LIFETIME milliseconds.
   After the expiration time, the route MAY be expunged from the node's
   route table.

   After broadcasting a RREQ a node waits for a RREP, and if the reply
   is not received within RREP_WAIT_TIME seconds, milliseconds, the node may
   rebroadcast the RREQ. The RREQ may be rebroadcast up to a maximum of
   RREQ_RETRIES times.  Each rebroadcast has to increment the Broadcast
   ID field.  The node MAY choose to use larger TTL values in the IP
   header field, or wait for longer times for the RREP to arrive.

7.3.

6.3. Forwarding Route Requests

   When a node receives a broadcast RREQ, it first checks to see
   whether it has received a RREQ with the same Source IP Address and
   a broadcast ID fields field of equal unsigned integer value within the
   last BCAST_ID_SAVE milliseconds.  If such a RREQ has been received,
   the node silently discards the newly received RREQ. Otherwise, the
   node checks to see whether it has a route to the destination.  If
   the node does not have a route, it rebroadcasts the RREQ from its
   interface(s) with the same field values, but using its own IP address in the IP header of the
   outgoing RREQ. The TTL or hop limit field in the outgoing IP header
   is decreased by one.  The Hop Count field in the broadcast RREQ
   message is incremented by one, to account to for the new hop through the
   intermediate node.  In this case, the node also creates or updates a
   reverse route to the Source IP Address in its routing table with next
   hop equal to the IP address of the neighboring node that sent the
   broadcast RREQ (often not equal to the Source IP Address field in the
   RREQ message).  This reverse route might be used for an eventual RREP
   back to the original node making which originated the RREQ (identified by the Source
   IP Address).  The  If no route exists for the Source IP address, or if an
   existing route would expire too soon, the reverse route is put into
   the route table with lifetime REV_ROUTE_LIFE milliseconds.

   If, on the other hand, the node does have a route for the
   destination, it compares the destination sequence number (dest-seqno)
   for that route with the Destination Sequence Number field of the
   incoming RREQ. If the node's existing dest-seqno is smaller than
   the Destination Sequence Number field of the RREQ, the node again
   rebroadcasts the RREQ just as if it did not have a route to the
   destination at all.

   If the node has a route to the destination, and the node's existing
   dest-seqno is greater than or equal to the Destination Sequence
   Number of the RREQ, then the node generates a RREP as discussed
   further in section 7.4.

7.4. 6.4.

6.4. Generating Route Replies (RREPs)

   If a node receives a route request for a destination, and has a
   fresh enough route to satisfy the request, the node generates a
   RREP message and unicasts it back to the node indicated by the
   Source IP Address field of the received RREQ. First, If the node is not the
   destination node, it copies over
   its the destination sequence number from
   the entry in its route table,
   or if table entry.  If the generating node is the node destination
   itself, it uses a destination sequence number at least equal to a
   sequence number generated after the last detected change in its
   neighbor set.  If set and at least equal to the node destination sequence number in
   the RREQ. If the destination node has not detected any change in its
   set of neighbors since it last incremented its destination sequence
   number, it may use the same destination sequence number.

   As part of the process of generating the RREP, the generating node
   creates or updates an entry in its routing table for the Source
   IP Address, if necessary as described in section 7.3. 6.3.  The Source
   Sequence Number is put into the route entry, along with the Hop Count
   from the RREQ. The expiration time for the route table entry is set
   to the current time plus ACTIVE_ROUTE_TIMEOUT seconds. milliseconds.

   If the generating node is not the destination node, then the
   generating node calculates the Hop Count between the Source IP
   Address and the Destination IP Address by adding together the Hop
   Count from the RREQ and the hop count stored places its distance in the route table entry
   for hops from the destination node.  If, on
   in the other hand, Hop Count field.  If the generating node is the destination node itself,
   node, it places the value zero in the Hop Count field.  The Hop Count
   field in is incremented by one at each hop as the RREP is
   simply equal forwarded to
   the source.  When the RREP reaches the source, the Hop Count received will
   represent the distance, in hops, of the RREQ. destination from the source.

   If the node is not the destination node, it calculates the Lifetime
   field of the RREP by subtracting the current time from the expiration
   time in its route table entry.  Otherwise, if the generating node
   is also the destination node, it copies the value MY_ROUTE_TIMEOUT
   into the Lifetime field of the RREP. Each node MAY make a separate
   determination about its value MY_ROUTE_TIMEOUT.

   If the generating node is not the node indicated by the Destination
   IP Address, then it puts the next hop towards the destination in the
   active-list for the reverse path route entry.

7.5. Generating Hello Messages

   Every

6.5. Maintaining Local Connectivity

   Each forwarding node generates SHOULD keep track of which of its neighbors are
   active next hops (i.e., which next hops have been used to forward
   packets towards some destination within the last ACTIVE_ROUTE_TIMEOUT
   milliseconds).  Each forwarding node SHOULD attempt to determine
   which of its active next hop neighbors are actually within its
   broadcast range by using the following procedure.

   When a "hello" message once every HELLO_INTERVAL
   milliseconds.  This hello message is forwarding node receives a broadcast RREP with TTL = 1, (unicast or multicast) packet
   from one of its active neighbors, and retransmits the message fields set as follows:

      Destination IP Address packet to
   the node's IP address,
      Destination Sequence Number next hop, the latest sequence number

      Hop Count   0

      Lifetime    (1 + ALLOWED_HELLO_LOSS) * HELLO_INTERVAL

   The Hello Messages MAY also contain extensions denoting node SHOULD NOT transmit any additional data for
   NEXT_HOP_WAIT milliseconds.  Instead, the
   multicast groups which are known node SHOULD listen to see
   if the node, along with next hop retransmitted the groups'
   corresponding groupheads.  These extensions packet.  If the retransmission is
   detected, the node can be used by nodes
   which have just joined the network to fill in their Request Table
   up-to-date request information.  The information is also used for
   route rebuilding, as is described later.

   The extensions have assume that the following format:

      Multicast Group IP Address
                        IP address of known multicast group

      Multicast Grouphead IP Address
                        IP Address of corresponding multicast grouphead

7.6. Initiating Triggered Route Replies

   A node can trigger an unsolicited RREP if either it detects a link
   breakage for a next hop along an active route in is still within its route table, or
   if it receives
   broadcast range, and can then resume transmission.  Otherwise, the
   node SHOULD attempt to detect a RREP response from the next hop, using the
   following methods:

    -  Any suitable link-layer indication, e.g.  a neighbor with an infinite metric for an
   active route (i.e., containing link-layer
       acknowledgement, or a Destination IP Address for which
   there is CTS to receive the packet, or a route table entry with RTS the
       packet to its own downstream next hop.

    -  Receiving a nonempty active-list)

   The unsolicited RREP is ICMP ACK message from the next hop.

    -  A RREQ unicast to each neighbor in the nonempty
   active-list next hop, asking for the a route to that destination.  The contents of the
   RREP fields are set as follows:

      L           0

      Hop Count   65,535

      Destination IP Address next
       hop.

    -  An ICMP Echo Request message unicast to the next hop.

   The ICMP ACK message SHOULD be sent to a forwarding node by a next
   hop which is also the destination IP address shown in the broken route

      Destination Sequence Number
                  One plus IP header
   of the packet, when the destination sequence number recorded in has not sent any packets to the route.

7.7. Detecting Link Breakage

   A
   forwarding node can detect a link breakage by listening for "hello" messages
   from its set of neighbors. within the last HELLO_INTERVAL milliseconds.  If it the
   next hop cannot be detected by any of these methods, the forwarding
   node MUST assume that the link is broken, and take corrective action
   by following the methods specified in Section 6.6.

   A node MAY detect a link breakage by listening for broadcasts
   and ``hello'' messages from its set of neighbors.  If it has
   received hello messages from a particular neighbor, but misses more than
   ALLOWED_HELLO_LOSS consecutive broadcasts or hello messages from
   that neighbor, the node can presume MUST assume that the particular its neighbor is no longer able to maintain a direct
   link with
   in the mobile node. neighborhood.  When this happens, the node should assume
   that its link with the former neighbor has been broken, and SHOULD proceed as
   in Section 7.6. 6.6.  A node should SHOULD assume that a hello message has been
   missed if it is not received within 1.5 2.1 times the duration of the
   HELLO_INTERVAL.

   Alternatively,

   A node MAY offer connectivity information by broadcasting local
   ``hello'' messages as follows.  Every HELLO_INTERVAL milliseconds,
   the node can use any physical-layer or link-layer
   methods to detect link breakages with nodes checks whether it has considered as
   neighbors.

8. Node Operation - Multicast

   This section describes sent a broadcast (e.g., a RREQ) within
   the scenarios under which nodes last HELLO_INTERVAL. If it has not, it MAY generate
   RREQs, RREPs, and MINVs for multicast communication, a ``hello''
   message.  This hello message is a broadcast RREP with TTL = 1, and how
   the message fields in the messages are handled.

8.1. Maintaining Multicast Tree Utilization Records

   For set as follows:

      Destination IP Address
                  The node's IP address.

      Destination Sequence Number
                  The node's latest sequence number.

      Hop Count   0

      Lifetime    (1 + ALLOWED_HELLO_LOSS) * HELLO_INTERVAL

   In addition to regular Hello messages, each valid multicast group (containing
   leader will also broadcast a finite metric) Group Hello message system-wide every
   GROUP_HELLO_INTERVAL milliseconds.  This system-wide Group Hello
   message has IP TTL value greater than the diameter of
   which a node is a part, either because it the network
   and is initialized to a member hop count of zero.  The hop count value is
   incremented by one by each node as the group
   or because it message is a router for forwarded.  This
   Group Hello message contains the multicast tree, the node also
   maintains a list of those neighbors that are likewise a part IP Addresses of the
   multicast tree.  This active-list of neighbors is used for forwarding
   messages received Multicast Groups
   for which the multicast group.  A node will forward such
   a message to every neighbor listed as a part of is the Group Leader, along with the corresponding
   multicast tree,
   except that neighbor group sequence numbers.  Nodes in the multicast tree can
   use these messages to update their current distance from which the group
   leader.  The information in the message arrived.

8.2. Generating Multicast is also used for merging
   partitioned multicast trees, as is described later.  See Section 12.3
   for extensions needed to complete a GROUP_HELLO message.

6.6. Initiating Triggered Route Requests Replies (Triggered RREPs)

   A node sends a route request (RREQ) can trigger an unsolicited RREP if either when it determines that it
   should be detects a part of link
   breakage for a multicast group, and next hop along an active route in its route table, or
   if it receives a RREP from a neighbor with an infinite metric for an
   active route (i.e., containing a Destination IP Address for which
   there is not already a member
   of that group, or when it has route table entry with a message to send nonempty active-list)

   The unsolicited RREP is broadcast to inform each neighbor in the
   nonempty active-list for the multicast
   group but does not have a route to that group.  If the node wishes to
   join the multicast group, it sets destination.  The contents
   of the flag J RREP fields are set as follows:

      L           0

      Hop Count   255 (= infinity)
      Destination IP Address
                  The destination in the RREQ; otherwise,
   it leaves broken route

      Destination Sequence Number
                  One plus the flag unset.  The destination address of sequence number recorded for
                  the RREQ is
   always route.

7. Multicast Route Activation (MACT) Message Format

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |P|G|        Reserved                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Multicast Group IP address                   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Source IP address                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Source Sequence Number                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The format of the Multicast Route Activation message is illustrated
   above, and contains the following fields:

      Type        xx

      P           Prune flag; set when a node wishes to prune itself
                  from the multicast group address.  If tree, unset when the node has is activating a record
   of another node (the multicast grouphead) requesting to be
                  tree link.

      G           Group Leader flag; set by a multicast tree member
   of that multicast group, it has two options.  If the node has
                  fails to repair a known
   route multicast tree link breakage, and
                  indicates to the grouphead, group member receiving the message
                  that it will place should become the new multicast group leader.

      Reserved    Sent as 0; ignored on reception.

      Multicast Group IP Address
                  The IP address of that node in
   the extension field and will unicast the RREQ to the corresponding
   next hop Multicast Group for that destination.  Otherwise, if the node does not have which a
                  route to the grouphead, or if it does not know who the multicast
   grouphead is, it will broadcast the RREQ with destination is supplied.

      Source IP address
   set to the Address
                  The IP address of the multicast group, and it will not include
   the extension field.

   These scenarios can occur during initialization of a node, when a node discovers it should be a member of a multicast group, or when
   a previously valid branch of which originated the multicast tree expires.  Branches Route
                  Request.

      Source Sequence Number
                  The current sequence number for route information
                  generated by the source of the multicast route request.

   To prune itself from the tree become invalid if they time out (the Lifetime
   associated with (i.e., inactivate its last link to the route expires), or if
   multicast tree), a link breakage results in multicast tree member sends an infinite metric being associated MACT with the route.

   The process of waiting for a RREP 'P'
   flag = 1 to a RREQ with a multicast
   destination address is the same as next hop.  A multicast tree member that described in Section 7.2.
   The node may resend the RREQ up to RREQ_RETRIES times if a RREP is
   not received.  If the original RREQ was unicast has more than
   one next hop to a specific node
   and a RREP is not received within RREP_WAIT_TIME seconds, the node
   will broadcast the next RREQ (and all subsequent RREQs for that multicast group) across the network.  The destination IP address of
   the rebroadcast is set tree SHOULD NOT try to prune itself
   from the address of multicast tree.

8. Node Operation - Multicast

   This section describes the scenarios under which nodes generate
   RREQs, RREPs, and MACTs for multicast group, communication, and how the extension field containing
   fields in the messages are handled.

8.1. Maintaining Multicast Tree Utilization Records

   For each multicast grouphead address tree to which a node belongs, either because it
   is
   not included.  If a RREP member of the group or because it is not received after RREQ_RETRIES total
   requests, a router for the multicast
   tree, the node may assume also maintains a list of next hops -- i.e., those
   neighbors that there are no other members likewise a part of
   that particular group within the network.  If it wanted to join multicast tree.  This
   list of next hops is used for forwarding messages received for
   the multicast group, it group.  A node will then become forward a multicast message to
   every such next hop, except that neighbor from which the message
   arrived.  If there are multiple next hops, the forwarding operation
   MAY be performed by broadcasting the multicast grouphead for packet to the node's
   neighbors; only the neighbors that belong to the multicast group and initialize tree will
   continue to forward the destination sequence number multicast packet.

8.2. Generating Multicast RREQs

   A node sends a multicast RREQ either when it determines that it
   should be a part of
   the a multicast group.  Otherwise, if group, and it only wanted is not already a member
   of that group, or when it has a message to send packets to that the multicast
   group without actually joining but does not have a route to that group.  If the node wishes
   to join the multicast group, it will drop sets the
   packets it had for that group.

   Each node `J' flag in the network receiving a RREQ message with RREQ;
   otherwise, it leaves the J flag
   set, i.e.  every member unset.  The destination address of
   the network, checks their Request Table
   to see whether there RREQ is already an entry for this always set to the multicast group. group address.  If there is no entry for the group, the node records
   knows the IP Address
   of group leader and has a route to it, the node which sent the RREQ, together with will place
   the IP group leader's address of in the group for which it requested Multicast Group Leader extension
   (Section 12.2), and will unicast the RREQ to be a member, in the Request
   Table.  Because corresponding next
   hop for that destination.  Otherwise, if the first node does not have a
   route to request to be in a group becomes
   the multicast grouphead, entries in the Request Table represent
   multicast groupheads.  If a node wishes to join or send a message to
   a multicast group in the future, it will first consult its Request
   Table to see if another node had previously requested to join that
   group.  Based on the existence leader, or nonexistence of an entry for if it does not know who the multicast
   group in the Request Table, the node leader is, it will then send broadcast the RREQ as described at the beginning of and will not include the section.

8.3. Forwarding Multicast Route Requests
   extension field.

   The operation process of nodes forwarding RREQs waiting for a RREP to a RREQ with a multicast
   destination address is similar
   to that for the reception and forwarding of RREQs same as that described in Section 7.3, with the following exceptions.  If 6.2.
   The node may resend the RREQ is up to RREQ_RETRIES times if a join
   request, when the node creates RREP
   is not received.  If a reverse route RREQ was unicast to the Source IP
   Address, it places a route pointer in its multicast routing table, in
   addition to its (unicast) routing table.  Further, group leader and a
   RREP is not received within RREP_WAIT_TIME milliseconds, the node can only
   respond to
   will broadcast subsequent RREQs for that multicast group across
   the network.  If a join RREQ if it RREP is a member of not received after RREQ_RETRIES total
   requests, the multicast tree.  The
   generation node may assume that there are no other members of that
   particular group within the route reply (RREP) message is discussed in connected portion of the
   following section.

8.4. Generating Multicast Route Replies network.  If a node receives a multicast it
   wanted to join route request for a the multicast group, and it is already a member of MAY then become the multicast tree
   group leader for that multicast group and initialize the destination
   sequence number of the multicast group.  Otherwise, if it only wanted
   to send packets to that group without actually joining the group, it
   will drop the packets it had for that group.

   Each node updates its route and multicast route tables and
   then generates in the network receiving a RREP message.  It unicasts RREQ message with the RREP back `J' flag
   set MAY check its request table to see whether there is already an
   entry for this multicast group.  If there is no entry for the group,
   the node indicated by records the Source IP Address field of the received
   RREQ. The RREP contains the current destination sequence number for node which sent the multicast group, as well as RREQ,
   together with the IP address of the multicast
   grouphead.

   If a node receives a multicast join route request for a multicast group and it is not already a member of the multicast tree for that
   group, which it will rebroadcast the RREQ requested to its neighbors.

   If
   be a member, in the Request Table.  Because the first node receives a multicast route to request that is not a join
   message, it can reply if it has
   membership in a route to group becomes the multicast tree.
   Otherwise it will continue forwarding group leader, entries
   in the message.

   In Request Table represent multicast group leaders.  If the event that a node receives a unicasted
   multicast route request group leader changes at any time, the nodes will note this
   change by updating their Request Table so that specifies its own the node IP address as
   matches that of the destination address (i.e. new group leader.  If the source node believes this destination node wishes to be the join or
   send a message to a multicast
   grouphead), but the node is in fact not the grouphead, group, it can simply
   ignore the RREQ. The source node will time out after RREP_WAIT_TIME
   seconds and will broadcast a new RREQ without the grouphead address
   specified.

   Every time first consults its Request
   Table.  Based on the Multicast Grouphead sends existence of an RREP in response to a
   RREQ, it increments entry for the multicast group sequence number by one and
   attaches
   in this table, the new value of node will then send the sequence number to RREQ as described at the RREP.

   Regardless
   beginning of whether the this section.

8.3. Forwarding Multicast Route Requests

   The operation of nodes forwarding RREQs for multicast grouphead or an intermediate node
   generates the RREP, is similar
   to that for the RREP fields are set reception and forwarding of RREQs as follows:

      Hop Count    The distance described in hops the node initiating
   Section 6.3, with one exception.  If the RREP RREQ is from a join request, when
   the multicast grouphead.  This field is
                   incremented by each node that forwards the RREP along
                   the creates a reverse route to the source.

      Destination Source IP Address Address, it places
   the information in its Multicast Route table.  The IP address generation of the destination for which a
   route reply (RREP) message is supplied, discussed in this case the following section.

8.4. Generating Multicast Route Replies

   If a node receives a multicast grouphead.

      Destination Sequence Number
                   The destination sequence number associated with the
                   route to join RREQ for a multicast group, and
   it is already a member of the grouphead.

      Lifetime     The time multicast tree for which nodes receiving that group, the
   node updates its Multicast Route Table and then generates a RREP consider
   message.  It unicasts the route RREP back to be valid.

      Multicast Group IP Address
                   The the node indicated by the
   Source IP Address field of the Multicast Group.

      Multicast Grouphead IP Address received RREQ. The IP Address of RREP contains
   the Multicast Grouphead.

      Multicast Group Sequence Number
                   The current sequence number for the multicast group, the distance
   of the Multicast Group.

8.5. Route Deletion responding node from the nearest multicast group member,
   and the IP address of the group leader.  Further information about
   the multicast group leader is entered into the Multicast Tree Pruning

   When a Group
   Information extension (see Section 12.3).

   A node broadcasts an can only respond to a join RREQ message, if it is likely to receive more
   than one reply since any node in a member of the
   multicast tree can respond. tree.  If the RREQ was a join request, the RREP message traveling back
   to the node which originated the request sets up receives a multicast route pointers,
   effectively grafting request that is
   not a branch onto join message, it can reply if it has a route to the multicast
   tree.  If multiple
   branches to  Otherwise it will continue forwarding the same destination are created in such message.  If a manner, node
   receives a
   loop will be formed.  Hence, in order to prevent the formation of
   any such loops, multicast join route request for a multicast group and it
   is necessary to delete all but one not already a member of the routes
   created by the RREP messages.  The RREP containing the largest
   destination sequence number is chosen to be multicast tree for that group, it will
   rebroadcast the added branch RREQ to the
   multicast tree. its neighbors.

   In the event that a node receives more than one
   RREP with a unicasted multicast route request
   that specifies its own IP address as the same (largest) sequence number, it selects destination address (i.e.,
   the first
   one with the smallest hop count, i.e.  the shortest distance to source node believes this destination node to be the multicast grouphead.  After waiting for RREP_WAIT_TIME seconds,
   group leader), but the node must then deactivate all routes created by other RREPs.
   This is accomplished by broadcasting a multicast-invalidate (MINV)
   message.  The Destination IP Address of the MINV packet is set to in fact not the
   IP address of group leader, it
   can simply ignore the multicast group, RREQ. The source node will time out after
   RREP_WAIT_TIME milliseconds and will broadcast a new RREQ without the IP
   group leader address specified.

   Regardless of the next hop
   along the branch which was added to whether the multicast tree is included
   in group leader or an extension field.  The intermediate
   node generates the RREP, the RREP fields are set as follows:

      Hop Count field    Distance of the MINV is set responding node to 1.
   All nodes receiving this message whose address does not match that
   listed in the extension field of the packet will delete the nearest
                   multicast
   tree pointer to group member.

      Destination IP Address
                   The IP address of the node from which supplies a route to
                   the packet came. multicast group.

      Destination Sequence Number
                   The node which
   was chosen as the next hop sets the 'active' flag for destination sequence number of the sending node which
                   supplies a route to true, thereby finalizing the creation of the tree branch.

   Various scenarios exist multicast group.

      Lifetime     The time for the which nodes receiving the MINV message.
   If RREP consider
                   the node receiving this message route to be valid.

   The Multicast Group Information extension described in Section 12.3
   is also included.

8.5. Forwarding Route Replies

   If an intermediate node receives a member RREP in response to a RREQ that it
   has transmitted (or retransmitted on behalf of the multicast
   group, some other node), it will not
   increments the Hop Count and forward the MINV any further.  If it is not a
   member RREP along the path to the
   source of the multicast group and no other nodes use it as a router
   for the multicast group, it will propagate the MINV further up the
   tree, effectively removing (pruning) itself from the multicast tree.
   The Destination IP Address of the propagated MINV message is set
   to the IP address of the multicast group, and the extension field
   indicating the next hop is not included.  The lack of the next hop
   extension field indicates to all nodes receiving the packet that
   their multicast tree route pointer to this source node (if such a
   route pointer exists) should be deleted.  If the next hop selected
   by the source node's MINV message was not previously a multicast
   tree member, it will have propagated the original RREQ further up
   the network in search of nodes which are tree members.  Thus it is
   possible that this node also received more than one RREP. RREQ.

   When the node receives more than one RREP for the same RREQ, it
   operates in a manner similar to the source node by saving the route
   information with the greatest sequence number, and beyond that the
   lowest hop count; it discards all other RREPs.  This node forwards
   the first RREP towards the source of the RREQ, and then forwards
   later RREPs only if they have a greater sequence number or smaller
   metric.  When
   the node receives an MINV announcing it as the next hop, it will
   send its own MINV announcing the node it has chosen as its next hop,

8.6. Route Deletion and so on up the tree, until Multicast Tree Pruning

   When a node which was already broadcasts a part of RREQ message, it is likely to receive more
   than one reply since any node in the multicast tree is reached. can respond.
   If the RREQ was a join request, the RREP message traveling back to
   the node receives an MINV and discovers
   it was not chosen as which originated the next hop and is not otherwise request sets up route pointers, which
   may eventually graft a part of branch onto the multicast tree, it will delete the tree pointers and send an MINV
   without the next hop extension field tree.  If multiple
   branches to prune itself from the tree.

   When same destination are created in such a source node sends an MINV selecting manner, a next hop,
   loop will be formed.  Hence, in order to prevent the formation of
   any such loops, it sets is necessary to activate only one of the
   'active' flag for this next hop routes
   created by the RREP messages.  The RREP containing the largest
   destination sequence number is chosen to true.  If be the next hop also needs added branch to send an MINV message specifying which the
   multicast tree.  In the event that a node receives more than one
   RREP with the same (largest) sequence number, it has chosen as its
   next hop, it lists selects the IP address of this next hop in first
   one with the next smallest hop
   extension count, i.e., the shortest distance to a
   member of the MINV. Upon receiving this MINV message, multicast group.  After waiting for RREP_WAIT_TIME
   milliseconds, the source node will not delete must choose the tree pointer route it wishes to this node (even though use as
   its
   IP address is not listed in the next hop extension) because the
   'active' flag has already been set.

   To prevent the possibility of multicast group data messages being
   delivered link to the source node from multiple neighboring nodes before
   the MINV messages is broadcast, no node multicast tree.  This is allowed to forward accomplished by sending a data
   Multicast Activation (MACT) message.  The Destination IP Address of
   the MACT packet is set to this source node before the reception IP address of the MINV message. multicast group.  The nodes know they have not yet received the MINV
   node will unicast this message because
   the 'active' flag for that tree branch remains unset.  Only after
   receiving to the MINV and setting selected next hop, effectively
   activating the 'active' flag can route.  After receiving this message, the node node's
   neighbor to which the MINV is addressed forward any multicast group data packets
   to MACT was sent activates the node. route entry for the
   link in the multicast route table, thereby finalizing the creation of
   the tree branch.  All neighbors not receiving this message will time
   out and delete that node as a next hop for the multicast group in
   their route tables, having never activated the route entry for that
   next hop.

   Two scenarios exist for a neighboring node receiving the MACT
   message.  If this node was previously a member of the multicast
   tree, it will not propagate the MACT message any further.  However,
   if the next hop selected by the source node's MACT message was not
   previously a multicast tree member, it will have propagated the
   original RREQ further up the network in search of nodes which are
   tree members.  Thus it is possible that this node also received more
   than one RREP, as noted in section 8.5.

   When the node receives an MACT announcing it as the next hop, it will
   send its own MACT announcing the node it has chosen as its next hop,
   and so on up the tree, until a node which was already a part of the
   multicast tree is reached.

   If a multicast group member revokes its member status and wishes to
   remove itself from the multicast tree, it can do so if it is not a
   multicast router for any other nodes in the multicast group. group (i.e.,
   if it is a leaf node).  If this is the case, it may broadcast unicast to its
   next hop on the tree an MINV MACT message without with the next hop
   extension 'P' flag set and with
   the Destination IP Address set to the IP address of the multicast
   group in order to prune itself from the tree.  Similarly, if the node
   receiving this message is not a member of the multicast group and
   does not have any other nodes routing through it, it may send its own MINV
   MACT message up the tree.

8.6.

8.7. Repairing Link Breakages

   Branches of the multicast tree become invalid if they time out
   (the Lifetime associated with the route expires), or if a link
   breakage results in an infinite metric being associated with the
   route.  When a link breakage is detected between two nodes on the
   multicast tree, the node upstream downstream of the break (i.e. (i.e., the node
   which is further from the multicast grouphead) group leader) is responsible
   for initiating the repair of the broken link.  In order to build
   the route back up, this node will broadcast a RREQ with destination
   IP address set to the IP address of the grouphead group leader and with the J
   `J' flag set.  The destination sequence number of the RREQ is the
   last known sequence number of the multicast group.  The Multicast
   Group Hop Count field is set to the distance of the source node from
   the multicast grouphead. group leader.  Only a node which has a hop count for
   the multicast group smaller less than or equal to the indicated value can
   respond.  This hop count requirement is included to prevent nodes
   on the same side of the break as the node initiating the repair
   from replying to the RREQ. The RREQ is broadcast using an expanding
   rings search.  Because of the high probability that other nearby
   nodes can be used to rebuild the route to the grouphead, group leader, the
   original RREQ is broadcast with a TTL (time to live) field value
   equal to the Multicast Group Hop Count.  In this way, the effects of
   the link breakage may be localized.  If no reply is received within
   RREP_WAIT_TIME seconds, the RREQ milliseconds, all subsequent RREQs (up to RREQ_RETRIES
   total attempts) will be rebroadcast with a larger
   TTL value, and so on until the message is broadcast across the entire
   network or until the route is rebuilt. network.  Any
   node that is a part of the multicast tree and which had that has a multicast
   group hop count smaller than that contained in the RREQ can return an
   a RREP. If there is more than one RREP received at the originating
   node, route deletions occur as described in the previous section.

   If no response is received after RREQ_RETRIES broadcasts, it can be
   assumed that the network has become partitioned and the multicast
   tree cannot be repaired at this time.  In this situation, if the
   node which had initiated the route rebuilding becomes was a multicast group
   member, it will become the new multicast grouphead group leader for its part of
   the multicast tree partition.  It broadcasts a RREP with an infinity metric and Group Hello with the
   multicast group address extension field containing the corresponding
   multicast group IP address included.  The `U' flag in the Group Hello
   is set, indicating that there has been a change in the group leader
   information.  All nodes receiving this RREP message update their Request
   Tables to indicate the new grouphead group leader information.  Nodes which are
   a part of the multicast group tree also update the
   grouphead group leader information
   for that group in their Multicast Route Table to indicate the new grouphead.  All nodes will change
   group leader.  On the information
   in their hello messages to reflect this update.

   In other hand, if the event that node which had initiated the link break could
   repair is not be repaired, the a multicast
   tree will remain partitioned until the group member, there are two parts of the network
   become connected once again.  A node from one partition of the
   network will know that possibilities.
   If it only has come into contact with a node from
   the other side of the network by noting the difference in one next hop for the hello
   message multicast group information.  The node who is a part of the
   network partition with the lower grouphead IP address will initiate
   the tree repair.  It tree, it will unicast
   a RREQ message MACT message, with the R 'P' flag set
   back set, to the multicast grouphead of its partition in order to get
   permission to rebuild next hop, thereby
   indicating that it is pruning itself from the tree.  The node must seek permission to
   rebuild the tree in order to prevent multiple nodes
   receiving this message will note that it is coming from attempting its upstream
   link, i.e., from a node that is closer to rebuild the tree if contact between group leader than it
   is.  If the two partitions node receiving this message is
   re-established in more than one place.  Multiple repairs would create
   loops within the a multicast tree.  Additionally, since the node
   initiating group member,
   it will become the repair new group leader and will broadcast a Group
   Hello message as indicated above.  If it is not necessarily a multicast tree member, group
   member and it
   may only has one other next hop link, it will similarly
   prune itself have become disconnected from the multicast grouphead on
   its side of the partition, tree and so the lack of reply this process will prevent it
   from attempting to repair the tree.  The grouphead continue until a
   multicast group member is reached.  On the other hand, if the only node
   which can respond to an RREQ with the R flag set.  It will respond to initiated the request by sending an RREP granting permission to one rebuilding is not a group member and only it has more
   than one node to rebuild next hop for the tree, it cannot prune itself, since doing
   so would partition the tree.  Any nodes which requested permission  It instead chooses one of its next hops
   and which do not receive sends an RREP will time out and not attempt MACT with the
   repair.  As 'G' flag set.  This flag indicates that
   the RREP travels back next group member to receive this message should become the node, it will establish new
   group leader.  If the node's next hop is a
   multicast tree branch if one did not already exist.  After receiving group member, this node
   will become the RREP, group leader.  Otherwise, the node which sent the repair request will unicast a RREQ
   to its
   own MACT message with the grouphead 'G' flag set to one of its next hops, and
   so on until a group member is reached.

   In the other network partition, using the node it
   had received event that the hello message from as link break can not be repaired, the next hop.  This RREQ multicast
   tree will
   contain remain partitioned until the current value two parts of the partitions multicast group sequence
   number.  Upon receiving the RREQ, network
   become connected once again.  A node from one partition of the multicast grouphead
   network will take know that it has come into contact with a node from the larger
   other partition of its and the received multicast group sequence number,
   increment this value network by one, and respond with a RREP. As the RREP
   is propagated back to noting the source node, a branch on to difference in the Group
   Hello message multicast
   tree is added.  When the initiating group leader information.  A node receives the RREP, it will
   broadcast across which is a
   part of the network an RREP partition with an infinity metric and the
   multicast lower group leader IP address extension field containing
   and which is also a member of the corresponding multicast group IP address, and tree can initiate the
   tree repair.  It will unicast a RREQ message with the multicast grouphead IP
   address and `R' flag set
   back to the multicast group sequence number fields set leader of its partition in order to get
   permission to show rebuild the
   updated information.  All tree.  The node must seek permission to
   rebuild the tree in order to prevent multiple nodes receiving this RREP (i.e. from attempting
   to rebuild the entire
   connected portion of tree if contact between the network), will have two partitions is
   re-established in more than one place.  Multiple repairs would create
   loops within the updated multicast
   group information for that group. tree.  The group leader is the only node
   which was the grouphead
   of can respond to a RREQ with the other partition `R' flag set.  It will also note this message respond
   to the request by sending a RREP granting permission to one and only
   one node to rebuild the tree.  Any nodes which requested permission
   and which do not receive a RREP will time out and not attempt the
   repair.  As the RREP travels back to the node, it will establish a
   multicast tree branch if one did not already exist.  After receiving
   the RREP, the node which sent the repair request will unicast a RREQ
   to the group leader of the other network partition, using the node
   it had received the Group Hello message from as the next hop.  This
   RREQ will contain the current value of the partitions multicast group
   sequence number.  Upon receiving the RREQ, the multicast group leader
   will take the larger of its and the received multicast group sequence
   number, increment this value by one, and respond with a RREP. This
   is the group leader which will become the leader of the reconnected
   multicast tree.  As the RREP is propagated back to the source node, a
   branch on to the multicast tree is added.  When the initiating node
   receives the RREP, the tree will be reconnected.  The next time the
   group leader broadcasts a Group Hello, it will set the `U' flag to
   indicate that there is a change in the group leader information and
   group members should update the corresponding information.  The node
   which was the group leader of the other partition will also note this
   message and update its tables to indicate that the other grouphead group leader
   is now the multicast
   grouphead group leader for the entire network.

8.7.

8.8. Initiating Triggered Route Replies

   A node can trigger an unsolicited RREP if it has an entry in its
   Request Table for a multicast group, sends a RREQ to join the
   a multicast group, group and after RREQ_RETRIES times does not receives
   a response.  The node will then become the new multicast grouphead, group
   leader, and it will broadcast a RREP with infinity metric TTL (a Group
   Hello message) and with the multicast group / grouphead IP Address / Sequence
   number extension information set to reflect that it is now the grouphead group
   leader for the multicast group.  In addition, in order to ensure
   nodes maintain consistent and up-to-date information about who the
   multicast groupheads group leaders are, any node which is a grouphead group leader for a
   multicast group will broadcast an unsolicited RREP containing its
   IP Address and the multicast group IP address for which it is the
   grouphead such a Group Hello across the network
   every RREP_UPDATE seconds. GROUP_HELLO_INTERVAL milliseconds.  The contents of the RREP
   fields (including the Multicast Group Information Extension) are set
   as follows:

      L           0

      Hop Count   65,535   0

      Destination IP Address
                  The IP Address of the node sending the Group Hello.

      Destination Sequence Number
                  The node's latest destination sequence number.

      Multicast Group IP Address
                  The IP Address of the Multicast Group for which the
                  node is the group leader.

      Multicast Group Sequence Number
                  One plus the last known sequence number of the
                  multicast group.

   Nodes receiving the Group Hello incrememt the Hop Count field by one
   before forwarding the message.

9. Quality of Service

   AODV currently provides some minimal controls to enable mobile nodes
   in an ad hoc network to specify, as part of a RREQ, certain Quality
   of Service parameters that a route to a destination must satisfy.
   In particular, a RREQ MAY include a Maximum Delay extension (see
   Section 12.4) or a Minimum Bandwidth extension (see Section 12.5).

   If, after establishment of such a route, any node along the path
   detects that the requested Quality of Service parameters can no
   longer be maintained, that node MUST originate a ICMP QOS_LOST
   message back to the node which had originally requested the now
   unavailable parameters.

10. AODV and Aggregated Networks

   AODV has been designed for use by mobile nodes with IP addresses
   that are not necessarily related to each other, to create an ad hoc
   network.  However, in some cases a collection of mobile nodes MAY
   operate in a fixed relationship to each other and share a common
   subnet prefix, moving together within an area where an ad hoc network
   has formed.  Call such a collection of nodes a ``subnet''.  In this
   case, it is possible for a single node within the subnet to advertise
   reachability for all other nodes on the subnet, by responding with
   a RREP message to any RREQ message requesting a route to any node
   with the subnet routing prefix.  Call the single node the ``subnet
   router''.  In order for a subnet router to operate the AODV protocol
   for the whole subnet, it has to maintain a destination sequence
   number for the entire subnet.  In any such RREP message sent by the
   subnet router, the Prefix Length field of the RREP message MUST be
   set to the length of the subnet prefix.  Other nodes sharing the
   subnet prefix SHOULD NOT issue RREP messages.

11. Using AODV with Other Networks

   In some configurations, an ad hoc network may be able to provide
   connectivity between external routing domains that do not use
   AODV. If the points of contact to the other networks can act as
   subnet routers (see section 10) for any relevant networks within
   the external routing domains, then the ad hoc network can maintain
   connectivity to the external routing domains.  Indeed, the external
   routing networks can use the ad hoc network defined by AODV as a
   transit network.

   In order to provide this feature, a point of contact to an external
   network (call it an Infrastructure Router) has to act as a ``subnet
   router'' for every subnet of interest within the external network
   for which the Infrastructure Router can provide reachability.  This
   includes the need for maintaining a destination sequence number for
   that external subnet.

   If multiple Infrastructure Routers offer reachability to the same
   external subnet, those Infrastructure Routers have to cooperate (by
   means outside the scope of this specification) to provide consistent
   AODV semantics for ad hoc access to those subnets.

12. Extensions

   RREQ, RREP, and MACT messages have extensions defined in this version
   (and, possibly, future versions) of the protocol.  Extensions have
   the following format:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |    Length     |     type-specific data ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   where:

      Type     xx

      Length   The length of the type-specific data, not including the
               Type and Length fields of the extension.

   Extensions with types between 128 and 255 may NOT be skipped.  The
   rules for extensions will be spelled out more fully, and conform with
   the rules for handling IPv6 options.

12.1. Hello Interval Extension Format

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |    Length     |  Hello Interval ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ... Hello Interval, continued   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Type     xx

      Length   The length of the extension field.

      Hello Interval
               The number of milliseconds between successive
               transmissions of a ``hello'' message (RREP).

   The Hello Interval extension MAY be appended to a RREP message with
   TTL == 1, to be used by a neighboring receiver in determine how long
   to wait for subsequent such RREP messages.

12.2. Multicast Group Leader Extension Format

   This extension is appended to a RREQ by a node wishing to repair a
   multicast tree.

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |     Type      |    Length     |   Multicast Group Hop Count   |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |              Multicast Group Leader IP Address                |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Type     xx

      Length   The length of the extension.

      Multicast Group Hop Count
               The distance in hops of the node sending the RREQ from
               the Multicast Group Leader.

      Multicast Group Leader IP Address
               The IP Address of the Multicast Group Leader.

   This extension is only used for rebuilding a multicast tree branch.
   In that case, a route to the Multicast Group Leader was known before
   the need for the repair was discovered, and the IP address of the
   group leader is placed in the extension field.

12.3. Multicast Group Information Extension Format

   The following extension is used to carry additional information for
   the RREP message (see Section 5) when sent to establish a route to a
   multicast destination.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |    Length     |  Multicast Group IP Address ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ... Multicast Group IP Address  |  Multicast Group Seq Number ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ... Multicast Group Seq Number  |  Multicast Group Ldr IP Addr ..
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   .. Multicast Group Ldr IP Addr  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Type     xx

      Length   The length of the extension field.

      Multicast Group IP Address
               The IP Address of the Multicast Group.

      Multicast Group Seq Number
               The current sequence number of the Multicast Group.

      Multicast Group Ldr IP Addr
               The IP Address of the current Multicast Group Leader.

   This extension is included when responding to a multicast group
   RREQ. It is also used by a multicast group leader when sending a
   Group Hello.  The extension fields indicate which group the node
   is the group leader of and the current sequence number for that
   group.  For a Group Hello the Multicast Group Ldr IP Address field
   is not included, since this information is already indicated by the
   Destination IP Address field of the message.

12.4. Maximum Delay Extension Format

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |    Length     |          Max Delay            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Type         xx

      Length       The length of the extension field.

      Max Delay    The number of seconds allowed for a transmission from
                   the source to the destination.

   The Maximum Delay Extension can be appended to a RREQ by a requesting
   node in order to place a maximum bound on the acceptable time
   delay experienced on any acceptable path from the source to the
   destination.

   Before forwarding the RREQ, an intermediate node MUST compare its
   NODE_TRAVERSAL_TIME to the (remaining) Max Delay indicated in the
   Maximum Delay Extension.  If the Max Delay is less, the node MUST
   discard the RREQ and not process it any further.  Otherwise, the
   node subtracts NODE_TRAVERSAL_TIME from the Max Delay value in
   the extension and continues processing the RREQ as specified in
   Section 6.3.

12.5. Minimum Bandwidth Extension Format

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |    Length     |    Minimum Bandwidth ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     ...  Minimum Bandwidth        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Type         xx

      Length       The length of the extension field.

      Minimum Bandwidth
                   The amount of bandwidth (in kilobits/sec) needed
                   for acceptable transmission from the source to the
                   destination.

   The Minimum Bandwidth Extension can be appended to a RREQ by a
   requesting node in order to specify the minimal amount of bandwidth
   that must be made available along acceptable path from the source to
   the destination.

   Before forwarding the RREQ, an intermediate node sending the RREP.

      Destination Sequence Number
                  One plus MUST compare its
   available link capacity to the destination sequence number recorded Minimum Bandwidth indicated in the route.

      Multicast Group IP Address
                  The IP Address of
   extension.  If the Multicast Group requested amount of which bandwidth is not available,
   the node just became the grouphead.

      Multicast Grouphead IP Address
                  The IP Address of MUST discard the new Multicast Grouphead, i.e. RREQ and not process it any further.
   Otherwise, the node sending the RREP.

      Multicast Group Sequence Number
                  The Sequence Number of continues processing the multicast group, RREQ as set by
                  the new multicast grouphead.

9. specified in
   Section 6.3.

13. Configuration Parameters

   This section gives default values for some important values
   associated with AODV protocol operations.  A particular
   mobile node may wish to change certain of the parameters, in
   particular the NET_DIAMETER, MY_ROUTE_TIMEOUT, MY_TRAVERSAL_TIME,
   ALLOWED_HELLO_LOSS, RREQ_RETRIES, and possibly the HELLO_INTERVAL. In
   the latter case, the node should advertise the HELLO_INTERVAL in its
   ``hello'' messages, by appending a Hello Interval Extension to the
   RREP message.

      ACTIVE_ROUTE_TIMEOUT   3000

      ALLOWED_HELLO_LOSS     2

      BAD_LINK_LIFETIME      2 * RREP_WAIT_TIME

      BCAST_ID_SAVE          3000          30000

      GROUP_HELLO_INTERVAL   5000

      HELLO_INTERVAL         1000

      MTREE_BUILD            2 * REV_ROUTE_LIFE

      NET_DIAMETER           35

      NEXT_HOP_WAIT          NODE_TRAVERSAL_TIME + 10

      NODE_TRAVERSAL_TIME    40

      MY_TRAVERSAL_TIME      NODE_TRAVERSAL_TIME

      MY_ROUTE_TIMEOUT       6000

      REV_ROUTE_LIFE         RREP_WAIT_TIME

      RREP_UPDATE            5000
      RREP_WAIT_TIME         3 * NODE_TRAVERSAL_TIME * NET_DIAMETER / 2

      RREQ_RETRIES           3           2

   Note that the network may contain more than NET_DIAMETER ** 2 nodes.
   NET_DIAMETER measures the number of "cells" ``cells'' (typically wireless)
   that would have to be placed end to end in order to cover the area of the
   network.

10. Extensions

   RREQ, RREP, and MINV messages may have further extensions defined
   in future versions of the protocol.  These extensions will have the
   following format:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |    Length     |     type-specific data ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   where:

      Type     xx

      Length   The length of the type-specific data, not including the
               Type and Length fields of the extension.

   Extensions with types between 128 and 255 may NOT be skipped.  The
   rules for extensions will be spelled out more fully, and conform with stretch across
   the rules for handling IPv6 options.

11. network at its widest point.

14. Security Considerations

   Currently, AODV does not specify any special security measures.
   Route protocols, however, are prime targets for impersonation
   attacks, and must be protected by use of authentication techniques
   involving generation of unforgeable and cryptographically strong
   message digests or digital signatures.  It is expected that, in
   environments where security is an issue, that IPSec authentication
   headers will be deployed along with the necessary key management to
   distribute keys to the members of the ad hoc network using AODV.

References

   [1] S. Bradner.  Key Words for Use in RFCs to Indicate Requirement
       Levels.  RFC 2119, March 1997.

   [2] Charles E. Perkins.  Terminology for Ad-Hoc Networking.
       draft-ietf-manet-terms-00.txt, November 1997.  (work in
       progress).

Author's Address

   Questions about this memo can be directed to:

      Charles E. Perkins
      Networking and Security Center
      Sun Microsystems Laboratories
      901 San Antonio Rd.
      Palo Alto, CA 94303
      USA
      1
      +1 650 786 6464
      1
      +1 650 786 6445 (fax)
      cperkins@eng.sun.com

      Elizabeth M. Royer
      Dept
      Dept.  of Electrical and Computer Engineering
      University of California, Santa Barbara
      Santa Barbara, CA 93106
      1
      +1 805 893 7788
      1
      +1 805 893 3262 (fax)
      eroyer@alpha.ece.ucsb.edu