RE: [ns] Priority in ns, CBQ(parameters)

[Carlos Alberto Kamienski <cak@cin.ufpe.br>]

George

Now I understand clearly your question!
CBQ permits you implement a PQ-like and a WRR-like scheduler, or a mix of
both.
PQ and WRR have difference scheduling strategies. If you set two queues
with different priorities, then the higher priority queue will get strict
preference, and the lower priority queue could get starved!
Parameter allot_ has no effect when you are using priorities!
If you set two or more classes with the same priority, than you distribute
the bandwidth between them using allot_. (I  never used CBQ
mixing priority with allot).

So, if you just want to configure a simple PQ (two queues, one level),
then set different priorities to different queues and do not care about
allot_.
Otherwise, if you want to configure a simple WRR, give the same priority
to the queues and distribute the bandwidth using allot_.

Sorry for the confusion!

Carlos

> Hi Carlos!
> 
> Thanks for the answer!
> 
> My next question would be! What would happen if I had the same priority for
> both TCP and UDP packets, but still as before 60% allocation for UDP and 40%
> for TCP! Will there be any differences?
> 
> What function does the priority have, since the UDP is not allowed to use
> more than 60%? 
> 
> Thanks in advance
> 
> Regards	George
> 
> -----Original Message-----
> From: Carlos Alberto Kamienski [mailto:cak@cin.ufpe.br]
> Sent: Friday, November 17, 2000 11:57 AM
> To: George Khoury (ERA)
> Cc: 'Haobo Yu'; ns-users@isi.edu
> Subject: Re: [ns] Priority in ns, CBQ(parameters)
> 
> 
> > I thought since I have 60% and 40% allocation, the TCP could never get
> > complitely starved!! Am I wrong?
> 
> No. You are correct. This is the idea! Unless the CBQ implementation could
> present in some time a silly error, starvation should never happen if the
> queue has a minimum amount of link bandwidth.
> 
> Carlos
> 
> > 
> > Thanks in advance
> > 
> > Regards	George
> > 
>