Need help with Router Setup on Cable Modem

[Irnard]

Ok guys. Let me begin with this short story so you understand my problem. I am running 3 computers on SurfBoard 3100 Cable Modem and Linksys BEFSR41 Router (with latest firmware). Few days ago I lost ability to connect to my ISP (Adelphia) my modem worked fine, Activity LED flickering, but my router couldn't get IP from them. I decided to leave it for a day and see what happens (uninterrupted service with Adelphia is a fantasy). Next day it was the same. I called tech support. After 45 mins of waiting on hold and another 30 mins going thru the idiotic reset computer routine I was asked for MAC address of my cable modem. And at once I was advised to stay online for some Engineer. This very unfriendly engineer informed me that my Cable Modem was "shot down" (I guess they put my MAC address on their black list of modems that are not allowed to connect to system) because my router was holding same IP address for more than 3 hrs and that caused problems for other customers. I was also advised if this happens again I will be suspended. When I tried asking him what can I do to prevent it he stated that its not their problem but mine and routers and he cannot answer any other questions. Ok so my questions are:
1. Did anyone had similar problems with their ISP ?
2. I checked their User Agreement but unless they put this under "causing interference for other users" there is no other info about 3 hr limit on you IP address.
3. I thought ISP can reset your IP remotly and you cannot do anything about it. How can my router not allow their server to reset my IP ?
4. Why did I never found any thread in any broadband/network message boards about someone having this problem, altough I found a lot of people using same configuration and ISP ?
5. What should I do (besides coming home every three hours and unplugging cable modem and router to force IP reset which is out of question). Is there any Win 98SE (my OS) setup or my router setup which would fix this ?

One more thing I want to say. My image of broadband ISPs is falling badly. I had been Adelphia Cable Modem user for 3 yrs now. The speed is down every year getting slower (as oppose to faster) and now is terrible (unless you want to surf at 3AM) service is out every 2 days. Email service is out about 20% of the time. Techs are about as familiar with computers as my 8 yr sister and it always takes exactly 45 min to talk to a tech. On top of that they rised the price from $39.99 to $43.99. I hate them but I hate dial-up more and thats the only reason they have me as a customer now. So please. I now there are some proffesional network people in this forum who can reply to my questions. Thanks:rolleyes:

[perk]

Just asking, don't want to assume anything, you do have the router set up for DHCP right?

[cplclegg]

I think you found a tech who was talking out of his ass so to speak. There is no plausible reason that just because your IP is not renewing that it hurts others. I've had DHCP on my router for a year now and the IP never changed, this is even with power outages and moving my computer hardware around. Besides, the whole point of DHCP is for this instance when one IP gets locked for one user your modem can pick another one up and have no conflict. I hate tech support for this reason, they aren't properly trained to do the job at hand and often make the problem worse by making things up.

[Irnard]

Yes my router is set up for DHCP.
Now I am clueless. I also thought that DHCP should automatically assign IPs and that my router should not be able to interfere with that. What should I do now ? Live with day by day fear that they will suspend my account because I interfere with their DHCP server ? Please send some ideas what should I do with those buttheads now or in case they turn off my account. Thanks...

[HarveyWG]

What is it that you are doing on the net most of the time. I know I have an entirely different ISP than you. I have Time Warner RR, and they do limit the bandwidth usage, so if you try running a server on their system be it FTP, web server, or such, and you end up using a lot of the bandwidth available while having a residential account they will disconnect you w/o telling you. The only way you can use their service for stuff like that is if you have a commercial account for business purposes.

[Irnard]

Harvey,
No I am not running server here. I already looked thru their User Agreement and servers of any type are prohibited and I dont like to push my luck. I have 3 computers (Mine, my wifes and my parents) hooked up to the router. All of them are turned off when not used (no 24hr usage), but I dont switch off the modem nor the router, since they dont have power button and I preffer not to dive behind the desk to constantly plug those in and out. I noticed that since I had the router the activity LED on both (cable & router are constantly flickering even if all computers are off. Before when modem went straight to computer, if the computer was off the activity LED was OFF. That only leads me to believe that my router is constantly "talking" to the network. I checked the setup of the router and its set NOT to keep alive the connection and has Connect on Demand ON. Max Idle time is 30 mins. So everything seems ok on my side. I am totally lost why are they making this problem for me... as always any ideas are more than welcome...

[cplclegg]

Try talking to another tech. This 3 hour rule still bothers me. This would be the same thing as having a download for more than 3 hours going or even browsing the web for 3 hours straight. Let me ask you a strange question...how is the cable run to the modem? Is it tucked behind anything that is big and electric? I had a problem of my connection going out every 4 hours on the dot because my refridgerator would turn on and the interference would disrupt my cable modem because the wire was right behind the fridge. But call again and maybe you'll get a different answer. The only way you could possible be disrupting other customers if you have DHCP enabled is if the other customers are trying to use a static IP that has been already assigned to you or their network is overburdened and there aren't enough IP's to go around at one time. Neither sounds like it could happen.

[MtCableman]

Sounds like the "tech" gave you a line just so he could get you off the phone. That explaination is BS! Call again and again until you get someone who knows what they are taling about. You might even try the local office.

[Kip Patterson]

Just so I am clear on how you are configured, your router is set on the WAN side to obtain an IP address automatically?

Kip

[Irnard]

Hey guys, thanks for ideas. Let me answer some of your questions. My computer, modem and router are not close to any major appliances, also I don't have problem with connection now. The engineer who I talked to after being transfered from tech support clearly stated that THEY suspended my service and after that call he reopened it with the warning about not holding the IP for more than 3 hrs or ELSE (read: or you will go back to dial-up). I am telling you this company is screwed up badly. I seriously think that their network actually is overburdened and there are not enough IPs to go around. Thats the closest explanation for their action against me. KIP my router is set up to automatically get IP from them. Seriously guys there is nothing wrong on my side with the connection. I don't assign the IP myself. I think I will call them up for more info but I doubt that they will know difference between DHCP and CPR, still maybe... Right now I am trying to find in the router setup option to make him get IP from their DHCP server at least every 3 hrs, make him disconnect if I am not using net for more than 1 hr and disable him from keeping the connection if no one is using the net. I just don't want to get suspended for a month or more. If they do that I won't even know why, since explanation: "Because your router was holding IP for too long and that interrupted other customers doesn't make too much sense to me".

[computer nerd]

This is gonna sound weird, but here it goes.

I have a similar setup as Irnard. 3 computers, Toshiba PCX1000 Cable Modem, and BEFSR41 Router. One night I was surfing and downloading away. All of a sudden I lost my IPs on all computers. After hours and hours of troubleshooting I found out that it was a small space heater that my wife plugged in the other room but on the same circuit as the router in my office. This happened 3 different times. So, I had to unplug the power to the router for 30 seconds, plug the power back in, told my wife to NEVER use the space heater on that circuit AGAIN! I was able to reproduce the problem over and over again.

Don't know if this helps or has anything to do with you, but like I said WEIRD!

[Irnard]

Ok Guys.
Fresh update. After holding for 40 mins on hold I had a chance to talk to someone from Adelphia Tech a little smarter and more pleasant to talk to. I asked him for more detail about why my account was suspended because I want to take steps to avoid it. He checked my account notes and all that stuff and he told me that what is written is totally different from what the engineer person told me. He said my account was suspended because my router became "rogue DHCP server" (WOW ?!? sounds dangerous...) and it (my router) was broadcasting fake Adelphia IPs (which start with 24.x.x.x) which were picked up by different users and because of that about 30 customers, whose computers picked up those fake IPs, lost connection. They had to track me down (full scale router hunt) and when they did they suspended my account. He also told me that I should contact Linksys about that matter and ask them how to stop the router from doing that. Well, first I want to try you guys, maybe you will be able to help me. So basically forget about the first bs problem which was fed to me by the engineer. I think I am getting grey hair because of all this. Once again I am asking for any help regarding this problem. Plz help to stop this madness...

Mike

[Kip Patterson]

Aha.

When a user turns a computer on, it sends a broadcast out saying "help me, I need an IP". A DHCP server responds, and they engage in a little dialog which sets up the computer.

A standard exploit is to place a rogue DHCP server on the net, and hope that it responds before the real server does. The rogue server then assigns a default gateway that captures all the traffic from the computers it intercepted.

In order for this to work, the cable system has to be configured to relay the DHCP broadcasts to every cable modem, there has to be a DHCP server attached to the cable modem, configured to issue addresses in their IP range, and the CMTS at the head end has to be configured to relay the DHCP packets from that server. Finally, your linksys router has to have the ability to act as a DHCP server on the WAN side.

I don't think so.

What modem are you using, for starters?

Kip

[Irnard]

Kip,
I am using Motorola SurfBoard SB3100 and Linksys BEFSR41 combo. So you think that that this "rogue server" is another bs story from them ? Now I am TOTALLY lost.... :(

[Irnard]

Oh boy I guess I have to give up and see......

[Kip Patterson]

I went back and reread the DOCSIS spec - a scary experience!

The CMTS MUST NOT (emphasis theirs) forward DHCP broadcasts on the downstream.

I think they either don't understand or gave you some more BS.

Kip