Subject: Re: [manet] AODV RREP

From: Bart Braem <[email-masked]>
Date: Sat, 21 May 2005 13:53:28 +0200

> In AODV, during a route discovery process, if an intermediary node already
> have a route to the destination that is fresh enough, it can send back an
> RREP. The advantage of this function is it decrease the response time in
> large networks. however, I think this behavior has several drawbacks. First
> it allows blackhole attacks 

I do not think blackhole attacks can be prevented just by disabling 
intermediate RREP generation. 
E.g. using RERRs one could do almost the same, just broadcast a RERR, for an 
intermediate node on the route, to the next hop on that route. 
Another problem is that information contained in RREQs is also used to 
determine new routes, when a node broadcasts a RREQ with the targetted node 
as the originator other nodes may route through that node (because that nodes 
lies on the reverse path).

> and second it had a global effect of 
> "gathering" all the communication on a few routes. 

If they know where to find a specific node then they are good candidates for a 
route, probably the fastest route too. If you want real redundant networks 
AODV should not be used as the routing protocol.

> These routes become some 
> good targets for anybody listening to the traffic. I think a routing
> protocol should have a opposite behavior i.e. distribute the routes on the
> paths and thus reduce the risk of bottlenecks and reduce the damage and
> overhead due to link error.

AODV is focused on the shortest path (measured in hops), not on distributing 
information.

Of course these are my 2 eurocents...

Bart Braem

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