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Re: [ns] Expoo traffic
> I have a question about expoo traffic. I want to know if during "on"
> periods, packets are transmitted with a delay between them or not. Do we
> have : [][][][][][]____[][][] or [] [] [] [] [] []_____[] [] [] ?
>
> On Off On On Off On
The current implementation sends packets at a fixed rate (whatever the variable
rate_ is set to) during `on' periods. If that rate is the same as the link
speed, they will be sent back to back. If the rate is less than the link speed
they will be sent with a delay in between so the average over the on period is
rate_.
Note that upper layer protocols like TCP may change the way the packets
generated by the ExpOO generator actually go across the wire, due to timers,
slow start, etc. For example, if TCP backs off due to congestion but your
traffic generator keeps generating traffic, it will be sent in a large burst
when the congestion on the network goes away.
> In another hand, i've found in a computer science technical report*, that
> "the on-off source provided by ns simulator" doesn't correspond to any of
> the known on-off models". There is a new C++ class (for expoo.cc), and i
> want to know if it's necessary to replace the old one by this new
> proposition.
>
> *"On the specification of NS and other Known On-Off Sources"
I wouldn't know about that. Traffic in the 'real world' is a moving target, no
pun intended. Other factors in ns, such as fixed packet sizes &c may skew your
results even if you find a more 'realistic' traffic generator.
-Eric
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Eric H. Weigle CCS-1, RADIANT team
[email protected] Los Alamos National Lab
(505) 665-4937 http://home.lanl.gov/ehw/
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