[LARTC] leaky bucket on bursty multicast

Oivind oivindg at gmail.com
Wed May 24 13:18:25 CEST 2006


Thanks for replying :)
I have been playing a bit with the following setup, but unfortunately I
am confused about how to specify the queue length of my multicast class
below, to absorb the small bursts seen. It would be great with an example,
for example with a megabyte buffer.

# QDISC
tc qdisc replace dev eth3 root handle 1: htb default 30

# CLASSES
# root class
tc class replace dev eth3 parent 1:  classid 1:1  htb rate 5mbit ceil 5mbit
burst 50Kb cburst 100Kb
# multicast class
tc class replace dev eth3 parent 1:1 classid 1:15 htb rate 5mbit ceil 5mbit
burst 50Kb cburst 100Kb
# other traffic
tc class replace dev eth3 parent 1:1 classid 1:30 htb rate 1mbit ceil 5mbit

#filters here (not shown)


Thanks,
Oivind



On 4/8/06, Andy Furniss <andy.furniss at dsl.pipex.com> wrote:
>
> Oivind wrote:
> > On 3/1/06, Andy Furniss <andy.furniss at dsl.pipex.com> wrote:
> >
> >>Oivind wrote:
> >>
> >>>Hi all,
> >>>I have an average 2mbit multicast stream that once in a while bursts
> >>>high (up to 20mbit/s) in short periods (about 200ms). Could anyone
> >>>please help me with directions using tc for configuing leaky bucket
> >>>shaping to this stream? I have a 5mbit/s ceiling.
> >>>
> >>>My system is running gentoo linux 2.6.14, and I have compiled in all
> >>>QoS modules.
> >>
> >>I suppose it depends what you want to do with the burst ie. propogate it
> >>,smooth it without loss or drop packets to maintain  a rate.
> >
> >
> > I would like to smooth the bursts out at the ceiling bandwidth without
> > any packet drops (unless an unacceptable lengthy burst of course).
>
> Sorry for not replying earlier, I lost this one.
>
> What you want should be OK with htb/tbf/hfsc ratelimiting at 5meg - just
> choose a leaf queue/buffer length that can absorb the burst.
>
> Andy.
>
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