Subject: [manet] RE: manet Digest, Vol 12, Issue 13

From: Hyunwook Cha <[email-masked]>
Date: Thu, 14 Apr 2005 08:45:54 +0900

Hi Cindy,

As long as I understand AODV, DSN is essential for route discovery
because routing loop can be avoided through comparison between
maintained one in route tables and one in control messages. 

RREQ can not update existing route entries in receiving nodes because
sender node does not have valid route information. And receiving node
decides that it can generate RREP or not by comparing DSN in its table
with DSN in RREQ (hop count is also used for tie-breaking) unless the
"destination only" flag is set. In this case, when RREQ is forwarded
again, actually DSN in RREQ remains unchanged. Only if the "destination
only" flag is set, DSN in RREQ can be changed to make sure that RREP
generated by destination node can update routing table in nodes on the
reverse path.    

Hoping this helps.

HyunWook Cha

> Date: Wed, 13 Apr 2005 10:53:57 +1000
> From: Cindy <[email-masked]>
> Subject: [manet] the effect of destination sequence number
> To: "[email-masked]" <[email-masked]>
> Message-ID: <[email-masked]>
> Content-Type: text/plain; charset="us-ascii"
> 
> Hello all,
> 
> Following my previous question, can anybody who has
> a clear thoughs about destination sequence
> number(DSN) tell me, what is the effect of
> DSN during the RREQ transmission?
> 
> 2 facts are:
> 
> 1. the forwarding node will not modify its route
> table entry for the destination node during RREQ
> transmission.
> 
> 2. the node generating RREP simply copies its known
> or its own destination sequence number into RREP
> field, which is obviously the freshest one.
> 
> This means the RREQ will be accepted anyway if it is
> not a duplicate one.  I am wondering can we ignore
> the DSN during RREQ transmission?
> 
> Looking forward to any clarifications!
> 
> Cheers,
> 
> Cindy
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