> -----Original Message-----
> From: Simon Byrnand [mailto:simon@igrin.co.nz]
> Sent: Thursday, 01, November 2001 10:01 AM

> Yes, I think they use either a buffered or large windowed throttling
> algorithm, which is what I was getting at in my original
> message. If they
> are, I think its a good idea because it allows the overall
> download speed
> to be controlled, but without ruining the interactive responsiveness.
>
> Regards,
> Simon

I'm fairly sure you will find its the ATM layer that does all of the traffic
shaping. There is no need to complicate things with IP packet queueing, as
ATM has queuing and rate-limiting built in. I would hazard a guess that the
PVC (the VP=0/VC=100 for those who are interested) is configured as VBR-nrt,
which means you cannot set the maximum burst value to zero. Telecom
configure the JetStart service as 150kbps ATM for the sustained cell rate
and permit small bursts. ATM uses a funky algorithm to ensure that your
average cell rate stays at 150kbps, but allows it to go higher for very
short periods of time.

BTW, 150kbps of ATM = 128kbps of PPP/IP, its not a typo.

Cheers,
Nik

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Received on Thu Nov 1 10:36:19 2001