AODVv6 and IPv6 Global Connectivity

1
AODVv6 and IPv6 Global Connectivity

• Anders Nilsson
• Ph.D student
• Lund University, Sweden

2
Introduction

• Internet and Ad hoc networks
• AODV for IPv6
• GloMoSim simulator

3
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.

4
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.

5
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.

6
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

7
Sending Data

• Is destination local or global?
• Look up routing table, if found send as normally.
  If not found -gt 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.

8
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.

9
Default route issues

• If intermediate nodes receives a packet and has
  no route -gt 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.

10
Expanding ring issue

• How big area to search before assuming the packet
  in Internet?
• Default draft parameters -gt 2.2 sec delay for a 3
  hop scenario!
• One request only -gt 0.09 sec for the same
  scenario. Same delivery ratio.
• One request needs a carefully selected hop limit,
  because expanding ring isnt really used.

11
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.

12
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.

13
Future Work

• Testing and optimisations.
• Multiple Gateways
• Colliding networks
• Micro- and macro mobility, handoffs