How to shape traffic with burst???

tkmbe · 08-22-2013, 11:24 AM

Hello

I have the following "qos" script to limit the download traffic of clients on my router:

Code:

...
for i in $hosts; do
  host="$base.$i"
  echo "Creating $RATE class for host $host"
  $tc class add dev $DEV parent 1:0 classid 1:$i cbq bandwidth $DEV_MAX_RATE rate $RATE avpkt 1000 prio 5 bounded isolated \
  allot 1514 weight 1 maxburst 21
  $tc filter add dev $DEV parent 1: protocol ip prio 5 u32 match ip dst $host flowid 1:$i
done

For example download limit is 160kbps for each host.
What I want to add is that each host can use more bandwidth a short time, so "normal" web pages will be loaded "rapidly" and downloads and heavy pages will go with normal download speed.
So normal each host has 160kps but say for 1minute every 20min will download at 512kbps or something similar...

Any hints ideas how to do with burst or anything else?

Thanks a lot

Beat

Ygrex · 08-23-2013, 05:10 AM

have you looked at man-pages? http://linux.die.net/man/8/tc-cbq it does have parameters to configure burst

---------- Post added 08-23-13 at 10:11 AM ----------

oh, you use maxburst indeed; what is the question then?

baldy3105 · 08-24-2013, 11:46 AM

The "burst" you are talking about with traffic shaping works on a much smaller time scale that you envisage. Its really designed to ensure that a tcp window will be allowed in one go before the shape rate kicks in. It operates on the timescale of a fraction of a second, not what you are imagining. Over a period of seconds upwards it really does limit at an average of "bandwidth"

However having said that, you are not using traffic shaping you are using class based queueing. CBQ does not limit to "bandwidth" it provides a mnimum guarantee of "bandwidth". Bandwidth in this case is a minimum not a maximum.

If you have two classes set for 60/40% bw, either can use 100%. Only when both are contending for link usage will the 60/40% division be imposed on the traffic.

I'm not sure you can do what you are trying to do with normal QoS controls because its not what they are intended for.