[ns] TCP and packet drop: where are the retransmitted packets?

[Arne Lie]

 Ethan,

Thanks, I will have a look and see if full TCP header is possible; however,
I need only a unique sequence number series.

Arne

> -----Opprinnelig melding-----
> Fra: Ethan Giordano [mailto:giordano at cis.udel.edu] 
> Sendt: 27. juni 2006 12:49
> Til: Arne Lie
> Emne: Re: [ns] TCP and packet drop: where are the 
> retransmitted packets?
> 
> There are two different sequence numbers...the TCP sequence 
> number and the internal unique id for each packet. I think 
> you have to turn on tcp header output for the trace to see 
> the tcp sequence number.
> 
> ~Ethan
> 
> Arne Lie wrote:
> > Hi all,
> >  
> > For some time I have only been interested in the congestion 
> response 
> > of the different TCP congestion control algorithms, and the way it 
> > balances flow throughput to available capacity, packet drop 
> statistics, etc.
> >  
> > However, now I need to see how well TCP tackles 
> retransmissions, e.g. 
> > with SACK. When I inspect the event trace file, dropped 
> packets are "never"
> > retransmitted, in that ns-2 seems to increment the sequence numbers 
> > (both per flow and per simulation) all the time,
> >   
> >>>>>>>> making it impossible to know WHEN a retransmission 
> is performed.
> >>>>>>>>                 
> > <<<<<<<<<
> >  
> > Is this a correct observation? If yes, are there any 
> workarounds? If 
> > incorrect, how *do* I find the retransmission event, and e.g. how 
> > *many* packets are duplicated/retransmitted (SACK vs. non-SACK)?
> >  
> > best regards
> >  
> > Arne
> >