Basically N600 is a generic term covering a type or genre of wifi router and is not the model name. Its still Asus N56U.
(thus N600 can describe certain netgear and asus routers for example).
N600 routers are the first true dual-band routers on the market, capable of delivering 300Mbps Wi-Fi speed -- based on the dual-stream (or 2-by-2) setup of the 802.11n Wi-Fi standard -- simultaneously on its two frequency bands, 2.4GHz and 5GHz. The marketing term "N600" basically means "Wireless-N standard with a combined bandwidth of 600Mbps."--
Ain't nuthin but the blues! "Albert Collins".
Leave your troubles at the door! "Pepe Peregil" De Sevilla. Just Don't Wifi without WPA, "Yul Brenner"