asterisk users - May 2005 - QoS for improvements

Hello! Everybody!!,
I want to run VoIP in the same LAN (15 windows clients) which we use for
surfing the Internet. 6-7 softphones in the same client's machines is
'the
target'. My DSL is 128kbps, (I can go to 256kbps if required). So, I am told
to install some QoS's in the LAN to improve the voice quality. Frankly, I
don't know what it (QoS= Quality of Service) is. I hope you may help me
giving "Links" to read and briefing me your ideas.
Thanks to everybody in the list.
So far my success and progress are your help.
Thanks again
Kumara

> don't know what it (QoS= Quality of Service) is. I hope you may help me
> giving "Links" to read and briefing me your ideas.
1 minute of google search I found this :
http://compnetworking.about.com/od/networkdesign/l/bldef_qos.htm

which looks like a pretty nice explanation

hth

Kumara Jayaweera wrote:
> I want to run VoIP in the same LAN (15 windows clients) which we use for
> surfing the Internet.
Some magic words: QoS Asterisk HTB TC. Not easy to find good material 
over the internet, but Google may give you some ideas - how to use them 
is another problem, which you have to figure out alone, as there are a 
few resources to research.

Start here:
http://www.krisk.org/astlinux/misc/astshape

I've spent may hours to play with HTB QoS settings on the firewall, but with
absolutely no effect. In fact, this is normal, because the time required to let
a data packet going through the ADSL line will break the voice jitter. The only
right way to handle this issue is to modify the MTU on the router.

Without setting a TOS for voip, data where going through and voice was unusable.
With a lowdelay (0x10) TOS set for voip, voice was going through, but data was
blocked.
With a lowdelay TOS and an HTB QoS on the router, data where going through
slowly and voice was scambled.

After many tests, an MTU of 700 did work quite well. I did loose 15% of
bandwidth for data (twice more overheads), but data and voice may be used
together.

Those tests have been done on a 256 kbps up stream.

There is a quite good explenation about this issue on Cisco's web
site, and about they're LFI technology (link fragmentation and
interleaving):
http://www.cisco.com/warp/public/788/voice-qos/voip-mlppp.html#link_frag

Jean-Chrsitophe




Kumara Jayaweera a ?crit :
>Hello! Everybody!!,
>I want to run VoIP in the same LAN (15 windows clients) which we use for
>surfing the Internet. 6-7 softphones in the same client's machines is
'the
>target'. My DSL is 128kbps, (I can go to 256kbps if required). So, I am
told
>to install some QoS's in the LAN to improve the voice quality. Frankly,
I
>don't know what it (QoS= Quality of Service) is. I hope you may help me
>giving "Links" to read and briefing me your ideas.
>Thanks to everybody in the list.
>So far my success and progress are your help.
>Thanks again
>Kumara
>
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