By doing it this way you'll loose half your bandwidth (i.e 54 mbps down to @ 27 mbps), if you cascade them (hard wired from 1 of the 4 LAN ports on main router to 1 of the 4 LAN ports one the secondary router (NOT The WAN port! .... and you can disable WAN input on secondary router) you can retain the 54 mbps speed. If 27mbps is fast enough for what you are doing then it saves running a wire between routers. If you are using "newer routers" (Wireless-N or above) then half speed shouldn't be an issue