Re: [LARTC] time window in CBQ

[Stef Coene <stef.coene@docum.org>]

On Friday 05 September 2003 09:22, Andreani Luca wrote:
> Dear list,
>
> I have two linux boxes acting as VoIP Gateway in the following
> configuration:
>
>
>         IP Phone ----------+                 +------------------+
> +------------------+                  +---------------- IP Phone
>
> 		         |-----------eth0-| Linux BOX1
> |
> |-hdlc0----------hdlc0-| Linux BOX2 |-hdlc0-----------|
>
>         PC ----------------- -+                 +------------------+
> +-----------------+                   +--------------- PC
>
> The hdlc link is 64 kbps.
>
> I tried to make a configuration in order to guarantee the bandidth of the
> VoIP calls versus the data traffic between the two PCs.
> I used CBQ + Prio and U32 filter. The ip Phones mark the packet with TOS
> 0x40. I also need the entire bandidth available for data traffic
> when there are no calls.
>
> I used the following configuration:
>
>
> insmod /lib/modules/2.4.17_mvl21-sandpoint/kernel/net/sched/sch_cbq.o
>
> insmod /lib/modules/2.4.17_mvl21-sandpoint/kernel/net/sched/sch_prio.o
>
> insmod /lib/modules/2.4.17_mvl21-sandpoint/kernel/net/sched/cls_u32.o
>
> tc qdisc del dev $int root
>
> tc qdisc add dev $int root handle 1:0 cbq bandwidth $banda avpkt 1000 cell
> 8
>
> tc class add dev $int parent 1:0 classid 1:1 cbq bandwidth $banda rate
> $banda maxburst 20 avpkt 500
>
> tc class add dev $int parent 1:1 classid 1:2 cbq bandwidth $banda rate
> $banda_voce maxburst 20 avpkt 500
>
> tc class add dev $int parent 1:1 classid 1:3 cbq bandwidth $banda rate
> $banda_dati maxburst 1 avpkt 500
>
> tc qdisc add dev $int parent 1:2 handle 20: prio
>
> tc qdisc add dev $int parent 1:3 handle 30: prio
>
> tc filter add dev $int parent 1:0 protocol ip prio 1 u32 match ip tos 0x40
> 0xff flowid 1:2
>
> tc filter add dev $int parent 1:0 protocol ip prio 1 u32 match ip tos 0x00
> 0xff flowid 1:3
>
>
> According to the test I performed, the configuration works because the VoiP
> traffic has its bandwidth, however the voice quality is absolutely bad.
> This occurs because
> the bandidth is given in "avarage" while I need a more "instant" bandidth.
> How can I reduce the time window used to calculate the rate of the VoIP
> class. Note (in the script) that I tried setting maxburst=1 for the best
> effort class but had no result,
Check your bandwidth parameter :
http://www.docum.org/stef.coene/qos/faq/cache/5.html

Stef

-- 

stef.coene@docum.org
 "Using Linux as bandwidth manager"
     http://www.docum.org/
     #lartc @ irc.oftc.net

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