voip question

Hi,

 I've been using netfilter successfully -- thanks for
writing it.

I was wondering if I could improve my VOIP calls using
netfilter.

 The main problem is excessive jitter delay to the receiver
when P2P
or WEB uploads /browsing is/are occurring.

I have 512/128 ADSL and I am using tc-htb and using a
reduced MTU (576
bytes). The RTP data is getting through its just that the
jitter delay
is very long (seconds). The jitter delay returns to
unnoticeable when
the uploads are stopped. Some basic testing indicates that
jitter
delay is mostly unnoticeable if all other traffic is limited
to
24kbit(!) upload.

I was wondering if netfilter could detect the
outgoing/incoming RTP
traffic and then set a flag. After RTP traffic has finished
the flag
would be removed (using a timeout). The flag could then be
used to
CLASSIFY other packets into say a 24kbit upload pool.

 Looking at the iptables docs there is no specific module
that could
do this although you could hack the 'condition' module to
enable
setting of flags and add timeouts by reusing some of the
'recent'
module code. I am thinking about doing this, but I'd
thought I'd ask
first to see if anyone has any thoughts about whether its
been done
already or whether it would work or whether its too hard.

Thx,
Matt.

> -----Original Message-----
> From: netfilter-bounceslists.netfilter.org
> [mailto:netfilter-bounceslists.netfilter.org]On
Behalf Of Matthew Pepar
> Sent: Friday, March 24, 2006 6:58 PM
> To: netfilterlists.netfilter.org
> Subject: voip question
> 
> 
> I was wondering if I could improve my VOIP calls using
netfilter.

I use L7-filter coupled with tc and iptables to give VOIP
packets a higher priority over other packets:

	http://l7-filter.so
urceforge.net/

I hope that helps.
-pablo

ps:  If you want to see my prioritized traffic real-time,
you can go here:

	http://www.hillsandlakes.com/stats/graphs/shaping
_one_hour.html

pps:  I cap http uploads at 256kbps.

I wrote a module to do what I described, based on the
'condition'
module. Works well for me. Try it out if you have the same
problem.
http://condition2.
sourceforge.net.

On 3/25/06, Matthew Pepar <thepigsgmail.com> wrote:
> Hi,
>
>  I've been using netfilter successfully -- thanks for
writing it.
>
> I was wondering if I could improve my VOIP calls using
netfilter.
>
>  The main problem is excessive jitter delay to the
receiver when P2P
> or WEB uploads /browsing is/are occurring.
>
> I have 512/128 ADSL and I am using tc-htb and using a
reduced MTU (576
> bytes). The RTP data is getting through its just that
the jitter delay
> is very long (seconds). The jitter delay returns to
unnoticeable when
> the uploads are stopped. Some basic testing indicates
that jitter
> delay is mostly unnoticeable if all other traffic is
limited to
> 24kbit(!) upload.
>
> I was wondering if netfilter could detect the
outgoing/incoming RTP
> traffic and then set a flag. After RTP traffic has
finished the flag
> would be removed (using a timeout). The flag could then
be used to
> CLASSIFY other packets into say a 24kbit upload pool.
>
>  Looking at the iptables docs there is no specific
module that could
> do this although you could hack the 'condition'
module to enable
> setting of flags and add timeouts by reusing some of
the 'recent'
> module code. I am thinking about doing this, but I'd
thought I'd ask
> first to see if anyone has any thoughts about whether
its been done
> already or whether it would work or whether its too
hard.
>
> Thx,
> Matt.
>