Okay, now that we know what we are doing, let's do it!
Step 1: Configure SSID
The first step is the easiest step. What you need to do here is to configure both routers so they have the same SSID. This should be fairly straight forward. If these routers do not have the same SSID, when a mobile device moves to a different coverage location that mobile device will have to join the new network.
Step 2: Configure wireless security
Just like you did in step 1, you need to configure both wireless routers so that their security is the same. This means the security type as well as the password must be the same. If this differs, the mobile device will not be able to seamlessly roam between networks.
Step 3: Configure DHCP
This is where things get a bit tricky. You need to set up both routers so that IP addresses will be handled properly and neither router will issue a DHCP conflict. The first thing to do is assign each wireless router a static IP address. Let's use the 192.168.100. address scheme. We'll assume the 192.168.100.1 address is taken by the gateway, so you will use 192.168.100.2 and 192.168.100.3 for your wireless routers. We'll assign .2 to the primary wireless router and .3 to the secondary router. Now, here's another trick - when you are configuring the static IP addresses for your routers, you will want to only have one router on at a time (or only have one router on the network at a time.) When the router turns on it will most likely default to 192.168.100.1, so get one router working with a static IP address and then get the second working with the static IP address.
With the static IP addresses set you now must address DHCP. We can only have one router handing out DHCP or there will be addressing conflicts. So on the secondary router, turn DHCP off. On the first router you will turn it on, but you will also configure DHCP so that it will begin handing out addresses at the 192.168.100.4 address. You must not allow it to use the .3 address as that is being used for the secondary wireless router.
Finally, you'll want to make sure the primary and secondary wireless routers are not on the same channel and the channels are far enough apart as to not cause conflict (you could use channels 6 and 11 to make sure you won't have channel problems.)
Step 4: Locate and fire up!
The final step is to locate the routers such that, between the two, your entire building will be covered. Remember, the two routers will need to be able to "see" one another by way of ethernet. The easiest way to handle this is by plugging each into a wall jack that is directly connected to your network (and on the same IP address scheme as your routers.) If you don't have the ability to do this, you might have to run a cat5 cable from one to the other (which can run up the cost on this little project). When they are in place and connected, it's time to fire up both routers and get them online. When they are on line, grab a mobile device and connect to one of the routers. Once you have a connection made, walk from one router to the next to make sure you remain connected. You should. If so, congratulations, you just saved yourself some cash!
