Tributary boards receive signals in different rates and kinds from client side then encapslate it in the suitable OTN fame in ODU level and then send it to crossconnect boards .
It also can perform L2 operations for packet services.
Crossconnect boards
Do the matrix in ODU level for signals coming from tributary boards or line boards to OTN level and the reveres operation .
Also in MS-OTN
the cross connect board should have the ability to do the matrix in SDH form (VC12, 3,4) Level and in packet form (64K and upward)
Also in OTN form (odu0,1,2,3,4,e, flex).
Line boards
In OTN process signal cominfg from the crossconnect boards to OTU level and convert signal to one of the DWDM frequencies.
In MS-OTN
There is the universal line board that can send SDH, Pcket , and OTN services in one fiber using virtalization technology