LARTC - May 2001 - TBF question

Who can explain parameter buffer and limit in TBF

tc qdisc add dev eth1 parent 20:1 tbf rate 2Mbit buffer 30Kb/8 limit 15Kb

TBF uses internal 2 TBF control mechanism.  One for the short burst and
one for a long time control.  I think that buffer and limit contols ths
short burst and rate the long time traffic control.  I putted it on my
TODO list to test it out.

Gery Kahn wrote:
> 
> Who can explain parameter buffer and limit in TBF
>
> tc qdisc add dev eth1 parent 20:1 tbf rate 2Mbit buffer 30Kb/8 limit 15Kb
> 
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-- 

Stef

More QOS info : http://users.belgacom.net/staf/

hi,
> TBF uses internal 2 TBF control mechanism.  One for the short burst and
> one for a long time control.  I think that buffer and limit contols ths
> short burst and rate the long time traffic control.  I putted it on my
> TODO list to test it out.
limit is the sum of the bucket size (=burst) and the size of the queue. So
we police the traffic if limit is the same as burst (queue size is zero),
and we shape if limit is larger than burst (queue size larger zero).
rate/burst for the longtime controll, peakrate/mtu for the shorter
timescale (only if you need a upper bound), limit to decide about the
queue lenght. For more details look at...

http://www.cosy.sbg.ac.at/~kwagner/tbf02_kw.ps


That''s how I understand TBF. Correct me if I got it wrong.

Kurt