[ns] Confusion in AODV

following is the scenario,
http://dgr8swativekariya.wordpress.com/?p=13&preview=true
Scenario Image <http://dgr8swativekariya.wordpress.com/?p=13&preview=true>
I am using for the study of the protocols. At presently, I am studying the
AODV protocol.
In this scenario
node n0 is sending data to n11
after sometime, Node n8 is moving far from the other nodes, so node n8 is
doing local repair by initiating the RREQ for N11, but node N5, sends the
RRER to node N0. But after sometime node N11 send error message to the N0
and also initiates the route discovery for node NO.

I cant understand why the node N11 initiates the route discovery, while all
the links are bidirectional.

Please help me to understand this,
Thanks in advance

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*Swati Vekariya,
Pursuing M.E.(C.S.E)
Parul Institute Of Engineering and Technology.
*