Subject: [manet] link lenght and link optimization

From: Ehsan Ataie <[email-masked]>
Date: Tue, 9 Nov 2004 00:46:55 -0800 (PST)

hi,
is there any way for calculating link optimization
with ns2 in an ad hoc routing protocol? in other
words, i want to know the lenght of a link between a
source and its destination in e.g. DSR protocol and
also the lenght of the optimized link between those
nodes.
thanks in advanced.
Ehsan

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From: Dave Maltz <[email-masked]>
Date: Tue, 09 Nov 2004 06:24:54 -0500

> also the lenght of the optimized link between those

If you created your mobility traces using setdest, then the trace file 
probably already contains "god" information, which gives the shortest 
number of hops between two nodes at that point in time.  If your trace 
conforms to the expected format, you can use calcdest to add god 
information to a trace constructed using other means (e.g., another program 
such as ad-hockey)

You can then compare the number of hops a packet took with the shortest 
number of hops that existed at that time.

Caveats:
1) the "shortest number of hops" is calculated assuming the successful 
transmission range is a perfect circle of some pre-set radius.  This is a 
simplification of both the real world and how the simulator calculates 
successful receptions.

2) in a congested network, packets can be stuck in interface queues long 
enough that the nodes move substantially between when a packet is 
originated and when it is finally received at its destination.  This can 
cause packets to appear to take *less* than the shortest number of hops.

Cheers,
 -dam