Internet connection problem

[Dartgod]

I hope someone knows what's causing this.

I have Road Runner cable internet that runs to a Motorola wireless router. All the proper lights are lit on my cable modem and my home PC is connected via a LAN cable. After the computer sits idle for a long period (couple of hours or so) I lose my internet connection. Any web site I go to returns a DNS error. If I reboot, everything works fine. I'm pretty sure the problem is in the PC, but I can't figure it out.

Any of you fellow geeks have any ideas?

[nmt1]

Yeah, that is strange. I think it points to something being out of whack with the router though. Did you contact Motorola yet?

[HC_Chief]

Check with your ISP... they may be logging MAC addresses to insure you are putting only ONE system on the internet, per terms of your service agreement.

I know some ISPs do that.

You do not need to clone your PC's MAC address unless that's the address they have on file as the permitted address.

[Dartgod]

Originally Posted by nmt1

Yeah, that is strange. I think it points to something being out of whack with the router though. Did you contact Motorola yet?

No, not yet. I'm going to try to exchange it at Walmart first.

[Dartgod]

Originally Posted by HC_Chief

Check with your ISP... they may be logging MAC addresses to insure you are putting only ONE system on the internet, per terms of your service agreement.

I know some ISPs do that.

You do not need to clone your PC's MAC address unless that's the address they have on file as the permitted address.

I've thought about that. I wonder if cloning the modem address might help.

[HC_Chief]

Originally Posted by Dartgod

I've thought about that. I wonder if cloning the modem address might help.

Shouldn't have to. Unless, again, the ISP has some sort of MAC tracing enabled. Give them a call and see. I know when I was on Communistcast, they traced MAC addies, so I had to clone.

TWC doesn't... plus my service is 100% up and running at 5Mbps

[Dartgod]

Originally Posted by HC_Chief

Shouldn't have to. Unless, again, the ISP has some sort of MAC tracing enabled. Give them a call and see. I know when I was on Communistcast, they traced MAC addies, so I had to clone.

TWC doesn't... plus my service is 100% up and running at 5Mbps

I've got Time Warner (Roadrunner) also. I think I'll swap the router out and if I still have the same issue, call Motorola.

[nmt1]

Originally Posted by Dartgod

I've got Time Warner (Roadrunner) also. I think I'll swap the router out and if I still have the same issue, call Motorola.

Any update on the problem?

[Dartgod]

Originally Posted by nmt1

Any update on the problem?

Last night it was acting up so I hardcoded the DNS addresses on my NIC card TCP/IP properties. This morning it worked fine although Outlook had some problems connecting to my mail server initially. I got errors that it couldn't connect, but I hit Send/Receive again and it downloaded the mail just fine. I left the PC on all day so I'll see if it still connects ok when I get home.

[chiefz]

Essentially the WAN side (cable) will now pickup the DHCP address which used to be directed to your PC and the LAN side will be assigned an internal private address that will either perform NAT if you have multiple public IPs or PAT (most likely).

Sound to me like an arp cache problem on return traffic.

I can't see any other reason why you router would stop passing traffic to your PC but start again once the machince is reset or when you enable, then disable the MAC cloning option.

Basically when you do either of these things the CAM table of the switch is clear along with any arp entries associated with those MAC addresses.

The problem has to reside somewhere at the MAC/LLC layer (layer 2 of the OSI model) or on some layer offering support to both layer 2 and 3 like ARP.

Just out of curiousity, is there a setting in your router to clear the arp cache?

[chiefz]

Originally Posted by Dartgod

Last night it was acting up so I hardcoded the DNS addresses on my NIC card TCP/IP properties. This morning it worked fine although Outlook had some problems connecting to my mail server initially. I got errors that it couldn't connect, but I hit Send/Receive again and it downloaded the mail just fine. I left the PC on all day so I'll see if it still connects ok when I get home.

Also, check your BIOS for a setting called "Wake On LAN" and make sure that anything associated with the LAN functionality of your machine is disabled as far as power management is concerned.

What could be happening is that when you plug your machine directly into the cable it is on what is called a broadcast domain with all other machinces that share an IP address in your subnet mask range.

In other words it will hear broadcasts from other machines within its own network pretty well all of the time causing the NIC (network interface card) to never be able to go into sleep mode (if wake on LAN is enabled).

Now when you plug it in with a router in the middle it changes things.

Suddenly the public interface of your router in on that broadcast domain an you are on your own.

Routers will not forward broadcasts by default and eventually any TCP connections you had will timeout with no activity over a period of time.

With no traffic being received the NIC will shut itself down (sleep mode) if wake on LAN is enabled and will not come back up until new traffic is received.

Generally I always disable it because I have found that it rarely works like it is supposed.

Note: Most machines these days are Energy Star compliant and wake on LAN is enabled by default.

It might not be your issue but I have seen similar things happen before.

[Dartgod]

Update: I upgraded to the latest version of ZoneAlarm and the problem seems to have gone away. The PC has been on for 4 days straight without a reboot and the internet works everytime I've tried it. Thanks to all of you for your advice.