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									AODVv6 and IPv6
Global Connectivity
   Anders Nilsson
   Ph.D student
   Lund University, Sweden




                             1
Introduction
   Internet and Ad hoc networks
   AODV for IPv6
   GloMoSim simulator




                                   2
     Global Connectivity
   Internet Access from anywhere,
    including ad hoc networks.
   Ad hoc networks around 802.11
    hotspots or UMTS phones.
   Ad hoc networks in emergency
    rescue situations.




                                     3
Acquiring gateway information

   Address of an Internet Gateway.
   A globally routable prefix is needed
    to be reachable from the Internet.
   The gateway distributes its
    address and prefix.
   This information can be supplied in
    AODV RREQs and RREPs.


                                       4
Finding the gateway
   A new Internet Gateway multicast
    group is used.
   A node sends a special RREQ for
    the multicast address.
   The gateway responds with a „I‟
    flagged RREP providing its
    address and prefix.
   The node enters the address of the
    gateway as a default route.

                                     5
Addresses
   When searching for a gateway,
    any global address can be used,
    for example a Home Address
   If non is available, use the
    MANET_INITIAL_PREFIX.
   This address is deleted and RERR
    is sent
   DAD may optionally be used for
    the new address

                                       6
Sending Data
   Is destination local or global?
   Look up routing table, if found send
    as normally. If not found -> RREQ.
   If a default route exists, we MAY
    wait for a reply. If not acquire one.
   If we receive no RREP, send
    packet through default GW.
   If RREP is received, set host route
    and send as normally.

                                        7
Sending Data #2
   1: Use a routing header to specify the
    gateway and rely on normal AODV
    routing.
   2: Rely on default routes in intermediate
    nodes.
   1 means more packet overhead but
    conforms easier to current AODV draft.
   2 has less packet overhead but requires
    changes to AODV draft.


                                                8
Default route issues
   If intermediate nodes receives a
    packet and has no route -> RERR.
    The packet is dropped.
   Intermediate nodes must avoid
    sending RREQ or do gateway
    discovery. Cascading effect.
   Default routes can be setup by
    intermediate nodes when receiving
    RREP „I‟.
                                    9
Expanding ring issue
   How big area to search before assuming
    the packet in Internet?
   Default draft parameters -> 2.2 sec delay
    for a 3 hop scenario!
   One request only -> 0.09 sec for the
    same scenario. Same delivery ratio.
   One request needs a carefully selected
    hop limit, because expanding ring isn‟t
    really used.


                                           10
Some simulation results
   The fraction of “global” control
    packets is higher for low mobility.
   High mobility causes many link
    breaks and more “normal” AODV
    control packets.
   Small networks with high mobility
    have higher delay and lower
    delivery ratio.

                                          11
Conclusions
   AODV can be used for the
    necessary gateway signalling
   The methods seems to be working
    in both simulation and real
    implementation
   A few issues and sub problems
    need more work.



                                  12
Future Work
   Testing and optimisations.
   Multiple Gateways
   Colliding networks
   Micro- and macro mobility,
    handoffs




                                 13

								
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