What is this traffic?

Sorry, I hit Send by mistake.

Anyway, it appears to be once each second, and bringing up Status of the internet gateway shows it's 30 packets sent, and 24 received, each time. In Netstat I don't see any established connections that would account for this activity.

I've disabled the radio completely in the router, in an attempt to isolate the source of this traffic, but that didn't make any difference. I also tried putting the SB5120 cablemodem into standby mode, but that didn't change it either. So it's between the computer and the router, but with no established connection that's shown in Netstat.

Is this a periodic handshake between the two devices to make sure they are still there? Is there any way I can turn it off?

My guess is that it's UPnP, a service on your computer that allows you to configure your Router from your computer without going to the web interface.

Chris

you could download a protocol sniffer like EtherDetect and see what the traffic looks like.... That's what I use when things look weird around the router LEDs. Maybe some kind of monitor was installed & is running ?

If XP, try the ctrl-alt-del and take a look at the activity.