Problem hooking router to network

[Ksyder]

I was hooking up a router at a retirement community and they have a T1 line that is shared between about 300 apartments roughly. There is a router that hands out IP addresses there but the catch is that each apartment has its own cable modem. The existing cable wiring is used to send both the cable tv signal as well as the broadband internet.

Hooking up the single desktop pc to the cable modem works perfectly but hooking up the router to the modem and then having the client pc's connect to the internet will not work. I can ping the router no problem but can't get them on the net. The DHCP information that the router status' is showing 0.0.0.0 as the default gateway.

The ip address of the cable modem while hooked up to the pc is a private ip address, 192.168.1.225. The default gateway is 192.168.1.254. When the router is hooked up however there is no default gateway present and it does not work when trying to get to external websites, although they are showing up on my dhcp clients table and I can ping everything.

The router I'm trying to use is Linksys wrt54gs . Thanks in advance for any advice and I'll provide more info if you need it.

 

[MustISO]

Check to be sure that the modem does not have also have a router built in. I've seen DSL modems like this and you need to set the modem to bridge mode so the router can work like normal.

 

[Ksyder]

Its basically a motorola surboard modem, no built in router.

 

[JackMDS]

When you hook up a PC to the modem that and it is working, issue an IPCONFIG and see what its IP and Gateway is.

Configure the Router WAN port in a similar manner.

E.g., if the PC assumes 192.168.1.20 Gateway 192.168.1.254.

Take the PC of, and configure the Router's WAN port in a similar manner.

P.S. It is a little unclear how a T! turns into a cable Modem, and might be that their is authentication involved.

If it does not work when tried as mentioned above call the company that provides the out side service.

Many of this services have propriety "tricks" so that people would need the service provider for any change made. That is one of the ways that they insure their growing income. :shocked:

 

[Ksyder]

It is a little unclear how a T! turns into a cable Modem, and might be that their is authentication involved.

Each resident desiring high speed internet service uses a DOCSIS cable modem which are purchased with the system. The modem connects to an Ethernet card or USB connection in the residents computer. (The cost for the modem may be passed along as part of an installation fee or provided to residents as part of the cost for service.) The modems are administered and remotely turned on and off depending on who is authorized for service. The cable modem will work with any operating system with a network card (Macintosh, Linux, Unix, Windows) and USB will work with Windows 98 or better. Your SeniorTV cable headend is connected to the Internet using either a T-1 or DSL telephone line. A broadband router is located in the SeniorTV cable TV headend which shares the high speed internet connection with everyone on your cable system using the existing coaxial wiring. This is the same method used by large franchise cable TV operators except the cost is much less. Your cable TV wiring system and amplifiers are upgraded or replaced for 2-way capability so that the cable TV channels and computer downloads are delivered forward from the headend to the resident computer, and the resident's request or "send button" is delivered in reverse back to the headend.

I looked into cloning the dhcp info from the pc using ipconfig and copying it onto the router but the only way to specify a specific default gateway, etc was to configure the cable modem to use a static ip. The guy at the cable company mentioned above told me to use dhcp. I messed with the static ip settings but I wasn't clear on the right setting for all of them so I left it as dhcp. Should I look into setting it as static? the other thing is that if you go into the router configuration page and try to release and renew it would release but not renew. I would then have to reboot the modem and router and then it would get an address, but still no default gateway.

I'm wondering if it has anything to do with the subnet mask settings since you are basically hooking up a router to a router. I'm not an expert at networking so I know just enough to see that that might be whats causing the problem but I don't know how to fix it.

Edit- after reading the middle paragraph (copied from http://www.seniortv.org/internet.php) I noticed the thing about authorization for service. Shouldn't the cable modem mac address authorize the modem on the network? Normally the maintenance guys there hook them up via DHCP and they "just work". This is the 2nd router I've tried to hook up there that would not work and the first one the Geek Squad guys had working and then I cleared the settings and then it didn't work again. Thanks for any help. Most people don't have routers there since most people that live there have just 1 pc.

 

[spidey07]

Probably using mac address authentication (of the PC), try putting that mac in the router. Otherwise some key off of computer name. So do everything you can to make the router appear like the PC and look for any special software on the PC. And always make sure this complies with any acceptable use policy.

Pretty cool the company that is offering this, it's similar to other systems used in hotels.

 

[Ksyder]

Probably using mac address authentication (of the PC)

I've switched the residents pc's with my laptop directly to the cable modems many times and it worked as long as I reset the mac in the cable modem. Wouldn't that mean that the cable modem mac is authorized on the network, rather than the pc itself?

 

[Ksyder]

O.k. I was able to solve this problem... what I did was hook pc up to cable modem directly, do ipconfig/all, copy all info - ip address, gateway, dns, etc, and put it into router as static ip. Another thing I did was change the router ip address to 10.226.1.1 so that all ip's on my network would be 10.226.1.100 and higher so there would be no conflicts with the other addresses from the router servicing all the residents. In retrospect I probably should have left it as DHCP and just changed the Linksys IP address as I'm thinking this would work fine as well. I think the main problem was that both the "external" ip address and the linksys IP ranges were "192.168.1..." addresses and it was causing a conflict. Any thoughts on this? Thanks guys for the help.

 

[spidey07]

By statically assigning the routers external IP address you could potentially have an address conflict with somebody else later on.

 

[Ksyder]

I am hoping the DHCP lease will just keep renewing itself and there will be no problem then. The only other solution I can think of is what I mentioned about changing the internal address to be different then the other router's ip address range and then leaving the router as DHCP, but I didn't try that so I don't know if that would work. If it breaks in the future then I will be switching it up.

 

[xSauronx]

Originally posted by: krwilsonn
I am hoping the DHCP lease will just keep renewing itself and there will be no problem then.

:thumbsdown:

 

[spidey07]

By you setting static the DHCP client (in this case router) will not send any DHCP messages at all. The server will assume that address is available and hand it out to somebody. boom - address conflict and they are very difficult to diagnose unless you have access to their routers. You'll have really weird behavior.

 

[Ksyder]

uh oh thats no good.... judging by my earlier posts what should I do? I'm hoping having the lan side on a different address would fix it? And re-enable dhcp?

 

[nsafreak]

I'd recommend turning DHCP back on, it could be that having the LAN addresses coming from the router set as the same range that the downstream router was causing conflicts. Now that the router is handing out DHCP addresses in the 10.226 range it should be fine.

 

[Ksyder]

it could be that having the LAN addresses coming from the router set as the same range that the downstream router was causing conflicts

that seemed to be the case judging by the fact that when I tried to statically assign the ip address to the router and then have the router IP address as 192.168.1.1 it would come up with error message "Wan and Lan are the same... please re-enter" or something to that effect.

thanks guys for the advice you have been truly helpful.