A.O.D.V.%20Routing%20Algorithm

1
A.O.D.V. Routing Algorithm

• Ad-Hoc On Demand Distance Vector
• Distance Vector algorithm for Mesh networks
• Self-starting (OD)
• Network silent until routes are requested
• Link failure/Timeout/Error reporting
• Supports Unicast or Multicast routing
• No routing overhead in packets
• - Slow to insert a new link, Still uses Flooding

2
DSR-AODV Similarities

• Route Request Forwarding/Response
• Route request RREQ
• Propagates until destination is found.
• Route Reply RREP
• Destination sends reply back.
• Routing errors RRER
• When a link fails, a routing error is thrown back
  much like a reply would.
• Path Reversal
• Assumes symmetry in links
• Flooding
• Routing storage generally minimal
• No excess information is stored in the routing
  tables.
• During broadcast forwarding, network is clouded
  with temporary routes.

3
DSR-AODV Differences

• AODV is a Distance Vector algorithm
• Routing information is stored in the node, not
  the packet
• Maintains at most one route for a single
  destination.
• Routing tables are fresh.
• No stale information about nodes that are no
  longer accessible or necessary.
• Routing table timeouts handled per-node.
• Neighboring nodes exchange Hello messages (MAC
  Layer), which do not effect the routing tables or
  sequence numbers. If there is an error it will
  be reported on receipt of a route-request.
• Sequence numbers used as timestamps.
• Ensures RREQs not forwarded unnecessarily
• Keep up with a potentially dynamic network.

4
AODV Routing Table

• Routing table of each node maintains
• Next-Hop (Node Pointer)
• Sequence number (Integer)
• Hop Count (Integer)
• Values updated on receipt of RREQ, RREP, or RRER
• Partial order constraint.
• Seq(A) lt Seq(B) or
• Seq(A) Seq(B) HopCount(A) gt HopCount(B)
• Intermediate node (B) either has a newer route to
  endpoint than the start node, or it has a shorter
  route that is equally recent.
• Sorry Toucan Sam, this guarantees NO LOOPS!

5
AODV Implementations

• AODV-UU
• Kernel or User mode
• Also available for IPv6
• http//core.it.uu.se/AdHoc/AodvUUImpl
• NIST Kernel AODV
• Based on defunct mad-hoc
• http//w3.antd.nist.gov/wctg/aodv_kernel/
• WinAODV (Binaries)
• http//moment.cs.ucsb.edu/AODV/aodv-windows.html