30-06-2012, 05:51 PM
AODVjr - A Simplified Version of AODV
A Simplified Version of AODV.ppt (Size: 305 KB / Downloads: 43)
Ad hoc On-Demand Distance Vector (AODV) Routing
AODV is an ad-hoc routing protocol. It is able to discover a route through a network of computers.
Creates routes on-demand
Built for mobile networks
Loop free with quick convergence
Can scale to handle a few hundred nodes
Can be integrated into the existing protocol stack
When AODV was designed it incorporated many features designed to maximize performance at the cost of added complexity.
Simplicity
The goal of AODVjr is simplicity. Unlike AODV it does not require:
RERR messages
Sequence numbers
Precursor lists
Gratuitous RREP
Hop count
Hello messages
It is able to do this by requiring only destinations to reply to RREQ and uses end-to-end hello messages to maintain routes.
Link Layer Detection
Link layer detection allows a sending node to detect if a unicast packet is successfully received.
In simulations AODV using link layer detection provides amazing performance.
Currently it is impossible to access link layer feedback information in off the shelf hardware.
Current implementations use periodic hello messages to detect local link connectivity.
Hello messages cause a large amount of control overhead. Each node must periodically send broadcast packets. Each receiving node must also process them.
Control Overhead
AODV with hello messages
Every node in the network must broadcast a Hello message and every receiving node must process it. Routing overhead is controlled by the total number of nodes.
If a route breaks a RERR message must be sent to each node using that route, eventually reaching the source.
AODVjr
Connect packets are unicast from destination to source along active routes; routing overhead is affected by the number of active routes.
Conclusion
With currently available hardware AODVjr is as good as AODV with hello messages.
Routing overhead in AODVjr is related to the number of active routes, not the number of nodes.
RERR messages, sequence numbers and other optimizations could be added optionally to further improve performance.
Security can easily be added as there are no mutable fields in the control packets.
AODVjr is much simpler than AODV.