Terabit routers were developed specifically for optical networks and the carrier market. They have throughput rates in the terabit range and, in the most modern versions, can route several thousand OC-48 signals or several hundred OC-192 signals.
Terabit routers are used in the core network for mass throughput at maximum speeds, but also between the optical core network and the feeder networks. At the physical layer, Terabit routers are interconnected via Dense Wavelength Division Multiplexing( DWDM) and handle the transmission capacity imposed by the DWDM link. In the second layer, these routers operate as label switches and adapt incoming traffic to the DWDM structure. The third layer of Terabit routers has IP functionality.