[Asterisk-Dev] Re: Ethernet buffering problems causing jitter

[Mike Nugent]

On 2.6, the e100 has parameters on loading the module.  I found them in
the source to the module, but a google search turned up this:
http://www.winsystems.com/resources/appnotes/ftp/Intel82559/Linux/2.4_kernel/README.txt

I set the parameters on the firewall, not on the Asterisk box.  You
might also look into QoS.  I found that setting Asterisk to a higher
priority than anything else helped some.  Right now, it's set to 0x10
which would share a pfifo_fast queue with everything from ssh to
streaming audio.

I set this up on the outgoing interface on my firewall:
qdisc tbf 10: dev eth1 rate 1000Kbit burst 1536b lat 1.5s 
 Sent 15070755 bytes 191759 pkts (dropped 0, overlimits 0) 

qdisc sfq 40: dev eth1 quantum 1514b 
 Sent 10087494 bytes 21383 pkts (dropped 0, overlimits 0) 

qdisc tbf 30: dev eth1 rate 20Kbit burst 1600b lat 546.9s 
 Sent 45201468 bytes 382448 pkts (dropped 2419, overlimits 183331) 

qdisc sfq 20: dev eth1 quantum 1514b 
 Sent 64292311 bytes 542859 pkts (dropped 0, overlimits 0) 

qdisc prio 1: dev eth1 bands 4 priomap  2 3 3 3 2 3 1 1 2 2 2 2 2 2 2 2
 Sent 181152570 bytes 1715991 pkts (dropped 2419, overlimits 0)

The Asterisk packets are identified simply by the machine they come
from.  If this doesn't work for you, you could easily have iptables mark
the packets coming out of the Asterisk box and filter on that.

Hope this helps.



On Fri, 2004-03-19 at 08:52, Matt Lawson wrote:
> Yes this interests us as well.  Since we've started using VOIP there 
> have always  been intermittent quality problems.
> 
> My sysadmin is curious as to how exactly you did this, if it was with 
> ethtool or some other way?
> 
> Thanks.
> 
> > Last week we were experiencing lots of jitter due to our firewall not
> > handling packets smoothly.
> >
> > The firewall has two 82557's on it.
> >
> > In order to fix this, I used the e100 module and set RxDescriptors and
> > TxDescriptors to 1024 and flow_control to 1.
> >
> > Just thought this might interest people in the event that they're
> > getting the same problems.
-- 
Mike Nugent
System Administrator
Calltrex