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alex 05-04-2005 11:57 PM

QOS / TOC help on grandstream 486
Hi all,

I recently asked a question regarding QOS in uk.telecom and got no response,
so thought here might be a better idea...
I have a grandstream ATA486 set up in the recommended way, such that it is:
Cable modem > ATA > Wireless router > PC's. My problem is that I am on a
shared internet connection with other people in my house, and the QOS
facilities that I was hoping for in placing the ATA in front of the router
aren't what I'd thought. I live with some (irritating) bandwidth hogs,
however they are here to stay so the option of getting them to stop
downloading unfortunately doesn't exist.

When one of them starts downloading, although I can hear people OK, our
upstream isn't so good and there is a big delay in what I say and it is
constantly breaking up. As the ATA has all traffic from the router passed to
it before going to the cable modem, I want it to literally strangle the
bandwidth going to the router so it can reserve all the bandwidth it needs
for my VOIP calls. I believe this can be done by adjusting the Layer 2 and
layer 3 QOS settings, however do not know what these should be. I have tried
changing the values for layer 3 QOS (diffserv/presidence value), and
although it accepts the changes, doesnt seem to affect performance. If I
change the layer 2 settings, the ATA will not get an IP from the cable modem
so cannot connect for SIP services and none of the computers can access the

The manual says shocking nothing about these settings, and after emailing
support at grandstream I got the reply:
"Please try to swap the position of 486 and your wireless router by
connecting the 486 behind your wireless router to see whether this improves
a little bit. Or you may use our new f/w and set 486 into bridge mode."
which doesn't make much sense to me, as the instructions say that having the
ATA used as a client off the router gets rid of the QOS features it has. And
the firmware which they say to use to set it to bridge mode is still a BETA
version, so the box hasn't updated to it, and there are lots of reports on
the net about it being troublesome. Plus what would bridge mode do, I
thought bridging was linknig two networks together, whereas I almost want to
cut out the second part of the network (the Pc's linked from the wireless
router) when the phone is in use.

If anyone could help it would be much appreciated, or point me to the place
where I can get help.


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