dual-band router - technical definition

A wireless router that supports both frequency bands of the 802.11 wireless standard. Dual-band a/b/g routers handle 11a users in the 5 GHz band, while simultaneously supporting 11b/g users in the 2.4 GHz band.

Dual-Band N Routers
Dual-band a/b/g/n routers support both bands for 11n. They enable 11a and 11n users to transmit at 5 GHz and 11b/g and 11n users to transmit at 2.4 GHz; however, both bands may run simultaneously or only one band at a time. Simultaneous support provides load balancing and offers the most compatibility with all four standards (a, b, g and n). With simultaneous bands, data transfers could be configured, for example, on the 2.4 GHz network (SSID #1), while users who do video streaming could be configured on the 5 GHz network (SSID #2). See wireless router, 802.11n, 802.11 and SSID.

     802.11      Frequency
     Standard    Band

     11a         5 GHz

     11b         2.4 GHz
     11g         2.4 GHz

     11n         2.4 GHz and 5 GHz