Eduardo, the flag simply introduces a random delay to each packet (i. e. the CBR sources does not send 1 pkt ever T seconds, but every T+random(-T/2,T/2). I am not sure about the random interval, but this is the way it works, and it is useful to avoid that the two sources transmit at the same *exact* time.
Regards, Marco Fiore >---- Messaggio originale---- >Da: [EMAIL PROTECTED] >Data: 8-giu-2006 5.09 AM >A: "Marco Fiore"<[EMAIL PROTECTED]> >Ogg: Re: R: [ns] two equal UDP CBR flows in droptail queue get different bandwidths? > >That does this flag do exactly? >On Wednesday 07 June 2006 08:39, Marco Fiore wrote: >> Eduardo, >> >> it could be a synchronization issue. >> Try to avoid >> synchronization between flows >> by setting the random flag of the cbr >> flows >> to true: "$cbr_name set random_ 1". >> >> Regards, >> >> Marco Fiore >> >> >---- >> >> Messaggio originale---- >> >> >Da: [EMAIL PROTECTED] >> >Data: 7-giu-2006 >> >> 3.00 PM >> >> >A: <ns-users@ISI.EDU> >> >Ogg: [ns] two equal UDP CBR flows in >> >> droptail queue get different bandwidths? >> >> >Hi there: >> > >> >I've set up >> >> this experiment. I have two source nodes S1 and S2 directly >> >> >connected >> >> to a node R1 and two destination nodes D1 and D2 also directly >> >> >connected to a node R2. Nodes R1 and R2 are connected. All links are 1 >> >> Mb/s >> >> >Full duplex with DropTail. Now, here's the thing. I set up two >> >> flows, one >> >> >going from S1 to D1 and the other one form S2 to D2. Both >> >> flows are UDP CBR 1 >> >> >Mb/s. Flow 1 starts at t=0 and finishes at t=20. >> >> flow 2 starts at t=10 and >> >> >stops at t=15. Sim runs from t=0 to t=25. >> > >> >I'd expect that at t=10 (when flow 2 starts), both flows would >> >> experience the >> >> >same amount of packet losses, so that each one would >> >> use about 0.5Mb/s of the >> >> >link between R1 and R2. But what really >> >> happens is that from t=10 to t=15, >> >> >flow 2 uses all bandwidth while >> >> flow 1 loses all packets. Since both flows >> >> >have the same parameters, >> >> shouldn't they receive the same share of bandwidth >> >> >during that >> >> period? Or am i missing something here? >> >> >Thanks in advance. >> > >> >-- >> >Eduardo J. Ortega - Linux user #222873 >> >"No fake - I'm a big fan of >> >> konqueror, and I use it for everything." -- Linus >> >> >Torvalds > >-- >Eduardo J. Ortega - Linux user #222873 >" No fake - I'm a big fan of konqueror, and I use it for everything." -- Linus >Torvalds >
