Why is the activity light on my cable modem blinking?

[kgeissler 0]

It is hooked up to my Win2k Server machine. My cable modem activity light is always blinking. I am not sure what is sending data over my modem.

 

I checked my startup and there is nothing out of the ordinary running. I stopped all services which could be causing this, but it still blinks.

 

 

Does Win2k server have any services that hits the net all the time? If I shut the box off the blinking stops, so I know it is not data coming into the modem.

 

Any ideas?

[clutch 1]

Is the network card blinking at the same time this is going on? My modem still receives info even if it isn't passing it on to my router. Just a thought.

[kgeissler 0]

Yea...the light on the NIC is blink also...

[Busby 0]

Prolly/could be people port scanning you. I've had so many "alerts" from ZoneAlarm about like port scanning (I guess) tonight that it is scary. Had 21 (I did do the tests at grc.com though) cleared it, then I have like 23 now. Scary stuff that people scan/ping you all the time.

[kgeissler 0]

I have Norton Internet Security running and it shows nothing in the log.

 

BTW, the light blinks almost constantly.

[Dirty Harry 0]

DHCP...???

[kgeissler 0]

I thought about that too, but I would think that would be a one time thing till your IP address needs to be renewed.

[midngnd 0]

Mine is doing it as well still...and that's when the only thing I've got going is AOL IM. I know AOL IM isn't sending that much data, so I gave Time Warner a call. It's been going on a while since I called them, they told me about a month or so ago that they were doing something to their system to prevent viruses or some other b.s. But it still does it...and it gets annoying at night seeing the reflection of the activity light on the hub and modem on the wall.

[kgeissler 0]

Who is your ISP? I had ATT@home, but that got changed once @home went bankrupt. Now I have ATTBI. It only started when I switched.

[midngnd 0]

Time Warner is my ISP. (Roadrunner)

[Dirty Harry 0]

Could it be that your NIC is autodetecting the speed of the other devices and trying to get the cable modem to accept 100 Mbps speed? The modem only does 10 Mbps, but your card (likely) does 100 Mbps. This is no problem, but many NICs are by default on autodetect, i.e. they are figuring out the highest possible speed constantly. Try setting the NIC to 10 Mbps and see if the blinking stops.

[kgeissler 0]

Good idea...I will try that when I get home.

[kgeissler 0]

Well, that wasn't it. I changed the card to 10MB and it still blinked.

[MHz 0]

Could be spyware...use Adaware and make sure some advertiser isn't watching you too closely.

[OLEerror 0]

kgeissler, have your firewall block all Internet traffic and see if the modem continues to blink. If so, it may be your ISP polling the modem. It's not uncommon for cable ISPs to do this, even though they should only do it for short periods of time to test their system. Unfortunately, many allow it to happen constantly.

[ryoko 0]

Did I miss something? Your nic will always broadcast traffic. Take a look at a hub or switch. You can see when a broadcast occurs as every light goes off almost at once. Grab an old clunker, install just the OS and the nic. Basically just enough to get on the cable network. You will see the same happen. It is normal behavior. Every packet has info in it for what computer to send the data to. Your PC must read that to see if data is meant for you. Also there is a ton of communications between your pc and the other network devices, like the cable modem. Don't worry about the blinking light.

[DoubleTap 0]

I know someone that is running a sniffer and they say most of the traffic is ARP requests. Constant ARP requests.

 

DT