One router behind another

[the_guy]

I've read online about people having one router behind another. I was wondering if I have to modify anything on either router before I plug in the second one. I have high-speed cable internet, if that helps.

1 thing I'm concenred about is having to call my ISP. I just had one computer, and it was going directly to the internet. I bought a second one, and installed a wired router. Once I had installed my wired router, I had to call my ISP to reset my account, probably because the MAC address has changed from my original computer..

Then, a couple of years ago, I bought a wireless router. I set that up so all but one of my computers was wireless (last one's wired just in case the wireless failed, and to allow my network to work properly). I did not have to call my ISP after installing this router. Now comes my question.

If I reconnect my OLD router to my cable modem, and connect my new router behind it, will I have to call my ISP to reset my account again, provided it wasn't reset since the original router was installed? Also, what modifications do I have to do to my routers to make them work without a problem?

The reason that I want to do this is because I'm starting to repair computers for others. I want their computer outside of my home network, so if they have a network-aware virus, it cannot affect my computers when no one is logged on (thus allowing my antivirus to run, as I don't think antivirus apps run while Windows is on the welcome screen).

Thanks in advance, and I did search before I posted this, finding nothing.

the_guy

[bonestonne]

a network virus is a network virus, theres no way to isolate them once its on. to my knowledge, you can easily go from one of the outputs of one router into the input for the second router, and there shouldn't be a problem. the mac address shouldn't be affected at all, and it should work, but if your afraid they have adware/spyware, just don't connect them. have anti-spyware/virus/adware software on a CD, and run it before connecting them. better safe than sorry, always.

[puntoMX]

Get a manageable switch with webview. With that you can say what computer(s) can connect to what other computer(s) on the network. Also you can set throughput, always a nice plus.

Never use a router behind another router, use access points for that. Some firewalls can’t be disabled 100% and DHCP server can mess up things too.

Also you can build a server but it´s more expensive .

Edited October 8, 2006 by puntoMX

[the_guy]

Thanks for the replies guys. I don't have that much money on me, so I'll probably have to run antivirus/antispyware apps before connecting the computer to my network.

I'm just positive I saw somewhere before that showed how to use 2 routers on the same connection (one behind the other). Guess not then.

the_guy

[LLXX]

This is possible, not with the usual cheap 'routers' that are being sold everywhere (which are actually NAT boxes), but with 'real' routers; in fact, the Internet is mainly composed of interlinked Routers.

[the_guy]

@LLXX: I don't really understand what you're talking about. Could you please clarify?

Also, I read somewhere lst night that in order to do this, I would just have to disable DHCP on the second router. Can anyone confirm/deny?

the_guy

[DigeratiPrime]

you usually just disable DHCP on the second router if i remember correctly, so it acts like a switch instead, i believe this is called 'daisy chaining routers'.

[rendrag]

It would definitely work as digerati says, especially if you turn off the SPI firewall in the router interface.

However, could you not leave DHCP enabled, and just change the subnet and IP range router 2 provides? Wouldn't that completely isolate both networks? As LLXX states, the internet is made up of interlinked routers, so isn't this much the same?

I've been pondering picking up a cheat WRT54G off of ebay and using it as an internal router for test machines I don't want anyone else in my house getting access too.

Thoughts?

[ColdFusion200]

you're better off using a switch

[the_guy]

Thanks for the replies. If I get a chance, I'll try it and get back to you on what I did.

Also, can anyone answer the other part of my original question?

1 thing I'm concenred about is having to call my ISP. I just had one computer, and it was going directly to the internet. I bought a second one, and installed a wired router. Once I had installed my wired router, I had to call my ISP to reset my account, probably because the MAC address has changed from my original computer..

Then, a couple of years ago, I bought a wireless router. I set that up so all but one of my computers was wireless (last one's wired just in case the wireless failed, and to allow my network to work properly). I did not have to call my ISP after installing this router. Now comes my question.

If I reconnect my OLD router to my cable modem, and connect my new router behind it, will I have to call my ISP to reset my account again, provided it wasn't reset since the original router was installed?

the_guy

[uid0]

If your isp ties you to one mac address, and it changes, then you may need to call them.

However, some routers can spoof a mac address, so if you are changing the one that connects to your isp, you might be able to trick them. It's only the external mac address of the router connected to the cable modem that you need to worry about, that's the only mac address your isp gets to see.

Edited October 12, 2006 by uid0

[rendrag]

if your old router is the primary connection to the cable/dsl modem, you don't need to tell your ISP that you added anything inside your home.

Frankly, you don't have to alert them to any changes in your network setup unless you replace the old router with a different one, and after you've updated the settings on the new router, the internet isn't working.

Generally, that means they've tied your account to a particular MAC address. You can either clone the old MAC (any router worth its salt will have a MAC clone feature), and then you won't need to tell them anything, or you can call them and have them change the registered MAC address.

[the_guy]

Ok. Thanks guys. I'll try it and see what happens.

the_guy

[LLXX]

Generally, that means they've tied your account to a particular MAC address. You can either clone the old MAC (any router worth its salt will have a MAC clone feature), and then you won't need to tell them anything, or you can call them and have them change the registered MAC address.

All of them have that capability now, and most NICs also do.