Can I chain two routers together keeping DHCP on both?

Question

I have read that I can connect a second router by turning off DHCP and NAT, but I want the second router to assign DNS (I'm using it as an access point for my kids, and will use OpenDNS family service to help prevent inappropriate web pages).

Can I chain the two routers together keeping DHCP on both? How?

It's a Pace 4111N (primary) and Linksys E3200 (secondary).

Solution 1

You really only want one DHCP server per network (or multiple ones working in a redundant configuration). If you have more than one on a given network, whichever DHCP server answers first is going to be the one that gets to configure that DHCP client. So if you have two separate configurations you want to "push" via DHCP, you can't do it predictably if both DHCP servers are on the same network - not to mention if the IP ranges overlap, you'll have IP conflicts.

However, in your case, it sounds like you really want two separate networks, one for your use and one for your kids. You can do this with what you have.

• One of your routers will be connected to your ISP. This router needs to be assigned the internal LAN IP 192.168.1.1, and hand out DHCP addresses on something like 192.168.1.2 through 192.168.1.50. Call this router Router A.

• Connect a cable from one of the LAN ports on router A to the WAN port on router B. Set Router B's WAN IP address to 192.168.1.51, and its internal LAN IP to 192.168.2.1. Tell it to hand out DHCP addresses on something like 192.168.2.2 through 192.168.2.50. Set the DNS settings on this router's DHCP to what you want for your kids.

Router A should work normally. If you have things you need accessible via the Internet, make sure it's connected to Router A and setup your port forwarding on Router A like you would on any normal router.

Router B will "get internet" through Router A.

Router B will be double NATed. This means it's very difficult for machines from the Internet to connect to anything behind router B. You probably want this since it's for your kids.

By segmenting your network like this, you'll have a separate network for you and your kids and can do what you want.

Solution 2

Set the DHCP ON for both routers. This is particularly nice for wireless connections when Router 1 is slow, you can flip the connection to Router 2. For hardwired connections, you can setup a batch file to flip the network settings to reflect the proper IP Address and default gateway. The method you've demonstrated forces everything to be routed through Router 1 unless you manually assign IPs.

1. Modem (provider gives 2 IP Addresses out Switch Port 1 and 2) or 2 separate modems (Cable and DSL)

2. Router 1 WAN connected to modem Switch Port 1.

   a. Set IP to 192.168.0.1 (default gateway1)

   b. Subnet to 255.255.255.0

   c. DHCP ON 192.168.0.3 to 192.168.0.100 (IP Address on devices)

3. Router 2 WAN connected to modem Switch Port 2.

   a. Set IP to 192.168.0.2 (default gateway2) (keep it on same subnet 192.168.0.xxx if you want connections on both routers to see each other, if you want connections to be isolated on independent networks put it on 192.168.1.xxx or 192.168.2.xxx)

   b. Subnet to 255.255.255.0

   c. DHCP ON 192.168.0.101 to 192.168.0.200 (IP Address on devices)

4. Router 1 LAN 1 connected to Router 2 LAN 1 (only if you want devices on either router to see each other)

Solution 3

Sure, the only thing you'll want to make sure to do is set them to different subnets. Most consumer routers are set to use 192.168.1.*

Just make sure to set the second one to be 192.168.2.* or something similar.

Assuming Internet > RouterA > RouterB, the one disadvantage you'll have is that systems attached to RouterA will not be able to access systems behind RouterB unless you set up routes.

Comments

[mgkrebbs]

You should be able to just set the second router to use OpenDNS for the DNS, while having DHCP and NAT only in the first router.

[David Schwartz]

@mgkrebbs That won't work. Since the second router won't be assigning DNS servers to clients, what DNS servers it uses won't affect anything.

[Aerik]

You said, "either forward just the DNS on the second router to OpenDNS" - but I didn't think that would work... won't the devices connected to the second router only get the DNS info from that router if they have DHCP through that router? Also, thank you but "change the DNS servers only in your TCP / IP properties" is insufficient because I want the Wii and the kids' other devices to get DNS lookups from OpenDNS as well (unless they're using their own DNS, and I can't help that).

[Aerik]

I had imagined something like this, but couldn't quite wrap my head around the details. I will try it and if it works I will mark it as the answer. Thank you for the detailed explanation!

[DavidPostill]

People are more likely to read your answer if you format it so it is not a wall of text. Please read Markdown help and edit your answer to add paragraphs and bullet points ... and remove unnecessary information.