CSU/DSU
From Wikipedia, the free encyclopedia
A CSU/DSU (Channel Service Unit/Data Service Unit) is a digital-interface device used to connect a router to a digital circuit such as a T1 or T3 line.
A CSU/DSU operates at the physical layer (layer 1) of the OSI model. CSU/DSUs are also made as separate products; CSUs and DSUs. Either or both may be part of a T1 WAN card or integrated into a DTE.
