Stacking routers

[himji]

Hi, I've got myself a router with a built in modem. I want to connect it to another router (wireless one) since I don't fancy buying a new modem when I've already got one built into this router.

I'm assuming that if I plug the new router directly into this one and then put it inot the DMZ, then I shouldn't hit any issues? Should this work? Will a router happily route through another router (surely this is all the internets based on right?

 

[Dev]

Yes, but most home routers have the ability to only work as a switch and this is the easier option. Say you have a setup of:
PC--router--router--PC

Since the majority of home routers are set to NATing and issuing DHCP addresses in the 192.168.1.x range you will run into problems with routing and preconfigured "WAN" interfaces. Say each of the two routers issue 192.168.1.x addresses to one PC each. This will be done on the "LAN" interfaces on both by default. When one of the PCs try to reach the other it will send a packet to 192.168.1.2 The router will not route this packet since both the PCs are on the same network as far as the router sees it.
Putting the other router in the DMZ only ensures that it has special (usually no) Firewall rules since the firewall will logically be on the inside network.

The other alternative is to set up different scopes on the DHCP server of each router and create the appropriate firewall rules so that the second network becomes "trusted".

The easiest by far is to uncheck those checkboxes These are NAT, Firewall and routing, or if you have a checkbox that says "work as bridge only" or something you can use that instead.

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[himji]

Thanks, that pretty much confirmed what I thought.

I've setup a private range already and I'll setup a new range for the new router so I won't have to worry about that. I think I mentioned in my original post that I'll put the wireless router in the DMZ so I shouldn't have to worry about firwalls or anything else either. Although I could use it as an extra security measure if I can be bothered on configuring it all correctly

 

[justaguy]

I have a setup very much like the one that you're describing here and wanted to ask you a question, since you obviously know more than I do about routers and networking. Here's what I want mine to look like:

DSL Modem->Wired Router->Wireless Router w/4 wired ports->PS2 and Wireless Desktop Connection

As of this moment, the Wired Router is not connected and the wireless router is serving one pc in the office with it (downstairs) via wired connection and the PS2 upstairs via wired connection. I am also using the wireless connection on a PC upstairs and a notebook.

I want to insert the plain router, while still using the wireless/4 port so that I can have the wireless access upstairs. This would bring it much closer to the wireless pc and I have heard that "higher is better" for wireless AP's.

As I understand your post, what I need to do to make this work is to configure DHCP to use different IP's on each router (i.e. 100-105 and 110-115)? Then configure the first (wired) router to trust the second network? Is there more to it?

I apologize for not really knowing much about the topic, but any help is appreciated.

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[Dev]

Almost. What you need to do is to look at the subnet mask. This is usually either 255.0.0.0, 255.255.0.0 or 255.255.255.0. I won't go into the details as it will only complicate things, but you need to change the one of the numbers above the 255s. So if your first adress range is 192.168.1.x with a mask of 255.255.255.0 the easiest is to change the 1 to a 2 so you get 192.168.2.x with a mask of 255.255.255.0 for the other network. If the mask is 192.168.x.x with a mask of 255.255.0.0 you need to change the 168. For example 192.169.x.x. As you can see I put x's in in the corresponding places to the 0's in the mask since everything above the zeroes are in the same network.
I recommend the first option (three 255's) since its easier to just think of the last number as a host address.
Hopefully I made it clear enough, but just ask if there is something you don't understand.

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[sparky853]

We use a combination wired/wireless routers all the time for small Lan parties (10-15ppl) and the only thing we have to do is disable DHCP on one router, as reassign the roouter IP address, as they are usually set at 192.168.1.1

If you set your first router with an IP address of 192.168.1.1 and enable DHCP, disable it and change IP address on your second router, you should be set.

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