I recently switched from SBC DSL to cable internet. I have a Scientific Atlanta DPC2100R2 series cable modem and a Linksys WRT54G router. When I had DSL, the “Internet” light on the router didn’t blink unless I was actually sending traffic back and forth - loading a web page or something like that. But with the cable modem, both the “Internet” light on the router and the “PC” light on the modem blink constantly, and occasionally it seems like my router is crashing. While the “Internet” light will blink, the WAN and port 1 lights stay solid, my computer can’t connect to the internet, and when I try to call up 192.168.1.1 in a browser it times out. Restarting the router fixes it, but sometimes only for a few minutes. The problem is intermittent, and started recently. The cable company says my connection is great, and when I’ve had the cable modem plugged directly into the computer I’ve had no problems. Does anyone know of a conflict between this modem and router? And what’s with all the traffic?
One bump, just in case.
Maybe somebody is portscanning you?
Port scans, Various worms trying to propagate them selves. There is a reason people use some kind of firewall software.
Just for the record, the only computers connected are Macs, so there’s no spyware or anything on the computers themselves. And I thought it might be port scans, but I thought it was odd that I never saw any activity like that with my DSL modem.
They probably are not seeing anything past the business end of the NAT firewall on the router.
Well I wouldn’t go that far as I’m sure with that attitude that there is no anti-spyware installed.
But does the router still show traffic when the macs are powered down?
Yes, even with the computers powered down, the network shows activity, and as I said, the WAN and Port 1 lights do not blink. I should add that the wireless network is secured with WPA2 Personal.
What speed and duplex settings are on the router and in the cable modem? I’m wondering if you have a mismatch. They should both be set to autonegotiate, not hard-set to 100FD or anything else.
Are you able to log into the cable modem and change the settings? If so, you should double-check them. Some modems (like mine) have to be manually set to be used with a router (I had to switch it from PPPoE to bridge mode.) I don’t know if this is the case with cable (I have DSL,) but it might be worth looking into.
I don’t think this is the complete answer, but remember cable modems operate in a different network mode than DSL. A cable modem is part of a LAN. You and your neighbors are sharing a LAN, which in turn is connected to the larger network run by the cable company (and hence to the internet) via a bridge somewhere in your neighborhood. IIRC, in all ethernet LANs, each machine sends out keep alive packets so that every machine knows they are there. It is part of the ethernet standard. I have always assumed that the traffic I see on my router are those overhead packets. If I am correct, during times when lots of machines are on there should be more packets. This does not depend on the other computers using the internet, just that they are powered on. Note that the packets don’t contain much information, just enough to tell the other network cards that there is something else connected. Remember also you are part of a LAN, so every packet you send and receive is going to every device (cable modem) on the network. I don’t know whether the cable modem forwards those packets to your home router. But if it does, anyone with the right software and hardware can capture all that traffic. For privacy all packets are encrypted according to the DOCIS standard for cable modems. How good that really is, I have no idea.