On Wednesday 18 December 2002 21:51, James Ma wrote:
> Hi, All,
>
> I did some work on QoS with CBQ. Basically, I wanted to separate VoIP
> traffic from other traffics and give it guarantied bandwidth. I used the
> following scripts to do the work,
>
> #!/bin/sh
>
>
> OPTION="allot 1514 maxburst 20 avpkt 1000"
>
>
> tc qdisc del dev eth0 root
>
>
> tc qdisc add dev eth0 root handle 10: cbq bandwidth 10mbit avpkt 1000
>
> tc class add dev eth0 parent 10: classid 10:2 cbq bandwidth 10mbit rate
> 34kbit $OPTION prio 3 bounded
>
> tc class add dev eth0 parent 10:2 classid 10:10 cbq bandwidth 10mbit rate
> 30kbit $OPTION prio 3
>
> tc class add dev eth0 parent 10:2 classid 10:20 cbq bandwidth 10mbit rate
> 4kbit $OPTION prio3
>
> tc filter add dev eth0 parent 10: protocol ip prio 3 u32 match ip tos 0x20
> 0xf0 flowid 10:2
>
> tc filter add dev eth0 parent 10: protocol ip prio 3 u32 match ip dst 0/0
> flowid 10:2
>
> tc filter add dev eth0 parent 10:2 protocol ip prio 3 u32 match ip tos 0x20
> 0xf0 flowid 10:10
>
> tc filter add dev eth0 parent 10:2 protocol ip prio 3 u32 match ip dst 0/0
> flowid 10:20
>
>
>
>
> It seemed working -- when there was no VoIP traffic, a ftp link was using
> all 34kbit rate. When there was VoIP traffic, the ftp rate dropped to
> 17kbit (which was correct because the voice traffic was using 17kbit).
> Unfortunately, the voice quality was not good. Even if without ftp traffic,
> there were packets loss for voice traffic (if you count from 1 to 20 with
> one handset, you miss certain figures on the other end, they are 4, 5, 8,
> 9, 12, 13 etc). Any one had the same problem before? Any one can explain
> it? Any parameter I should adjust to better suit this application?
What if you add a small prio qdisc to class 10:10 and 10:20 ??
tc qdisc add dev eth0 parent 10:10 pfifo limit 10
This is a short pfifo that can hold 10 packets.
Stef
--
stef.coene@docum.org
"Using Linux as bandwidth manager"
http://www.docum.org/
#lartc @ irc.oftc.net
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