Voice Over IP in UK - Vonage/Motorola VT2442 QoS problems...

Author

Vonage/Motorola VT2442 QoS problems...

PCPaul

2007-11-19, 7:11 pm

I have my house phone through Vonage to a Virgin 2Mb cable connection.
Generally it's very good, but sometimes, mainly when I have a torrent
downloading, the phone calls break up badly.

The cable modem is a Virgin-supplied motorola SB5100i (on an ex-Telewest
network, if it makes a difference). Vonage supplied a VT2442 Wan/VoIP/4
port router when I joined them. You'd think the two motorola boxes would
play nicely.

I know it could be just plain old overloading, but I've seen it happen
even when a torrent is only running at 1-2KB/s and there is nobody else
uploading from me. The network is otherwise quiet, and the activity
lights bear that out.

The phone gets better instantly if I kill the torrent.

Any ideas how to improve things? (Apart from scheduling torrents to only
run from 2am-7am, which is the current neighbour-friendly solution).

It seems like QoS *should* mean that the VoIP calls get a big enough lump
of the bandwidth anyway. Or am I missing something?

ßodincus

2007-11-20, 7:11 am

PCPaul wrote:
> I have my house phone through Vonage to a Virgin 2Mb cable connection. =

> Generally it's very good, but sometimes, mainly when I have a torrent=20
> downloading, the phone calls break up badly.
>=20
> The cable modem is a Virgin-supplied motorola SB5100i (on an ex-Telewes=
t=20
> network, if it makes a difference). Vonage supplied a VT2442 Wan/VoIP/4=
=20
> port router when I joined them. You'd think the two motorola boxes woul=
d=20
> play nicely.
>=20
> I know it could be just plain old overloading, but I've seen it happen =

> even when a torrent is only running at 1-2KB/s and there is nobody else=
=20
> uploading from me. The network is otherwise quiet, and the activity=20
> lights bear that out.
>=20
> The phone gets better instantly if I kill the torrent.
>=20
> Any ideas how to improve things? (Apart from scheduling torrents to onl=
y=20
> run from 2am-7am, which is the current neighbour-friendly solution).
>=20
> It seems like QoS *should* mean that the VoIP calls get a big enough lu=
mp=20
> of the bandwidth anyway. Or am I missing something?
>=20
Torrenting opens quite a lot of connections, both in and out.
Be sure that the router Vonage supplied is properly set to prioritize=20
VoIP traffic (port 5060 UDP for SIP signalling and some high range UDP=20
ports for RTP traffic - the real "voice" traffic. Sorry I can't help you =

with a proper port range, every device is set with its own, there is no=20
standard for it).
Be sure not to let your P2P client open too many connections, because=20
the router computational power may be insufficient to timely deliver the =

packets if the connections are too many.
Reduce the number of peers and connections until your voice is not=20
breaking up.
QOS doesn't reserve bandwidth, but handles how quick a packet should be=20
forwarded.
If your router computational power is constantly running at 100%=20
capacity, there is no room for QOS-prioritized packets.
On top of that, an x-TW 2Mb BB is (AFAIK) 256 Kb up, and if you max out=20
the uplink channel, your downlink stops completely. That's the way cable =

broadband [don't] work.
You loose half of your downlink speed when you push out a quarter of=20
your uplink speed.
It's a very fine balance that you can achieve only by trial and error,=20
tweaking you P2P client parameters to limit both the number of=20
connections (in & out) and the upload speed / available bandwidth.
Remember that VirginMedia Cable BB connections are under STM from 4pm to =

midnight, if you exceed your download (and in the future upload) daily=20
allowance in that timeframe, you're "throttled" down to a lower service=20
level.
The wise move IMPOV is to postpone torrent downloading through the night.=

Happy tweaking.

--=20
=DF=F8dinc=B5s=B2=B0=B0=B0 - The Y2K Druid
----------------------------
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