Feature: 1. 1U box SDH/MSPP with 1 or 2 STM-1 optical interfaces and 63E1 interface. 2. Optical interface supports ALS (Auto Laser Shutdown) function 3. Inter-working with popular SDH/MSPP products of various vendors 4. Support TUG3-TUG2-TU12 tributary channel numbering and time slot numbering at ease 5. Support internal, STM-1 line clock, external and tributary