How to add a second router as access point and wifi signal extender

Question

Previously I had 2 linksys routers and was able to configure them as one in separate areas of my house.  I think it is called cascading.  The 2nd router acted as an ethernet switch with 4 extra ports and it provided a wifi signal to areas of my house that previously had a weak signal when I used only one router.
I have since switched to an Airport Extreme as my main router.  I can't seem to get the same configuration with the linksys router, it is Model E1000 and has an "N" signal.  The Linksys E1000 I think is the newer model of the old WRT54G Linksys.  I can't get it configured to work.  I have searched high and low on the internet and can't find anything simple enough for a novice to understand.  I did read something that I may have to assign a "DHCP Reservation" on the Apple Extreme.  I couldn't figure that out.
Can somebody please offer some guidance on how to get this to work?
Thanks

Answer 1

You have two routers producing two networks with the same name, so they will show up as two networks on any type of scan by a wireless utility. This is normal.
If you had used two Linksys devices, they would probably show up as one network, not two. Linksys has a feature that allows this to occur, but this is not true of Apple devices.
As long as the wireless network name, wireless security and password match up between the two routers, the two networks will behave as if they were one. As computers change location, they will automatically connect to the wireless access point with the strongest signal.