Why is an STM-1 2F MS-SPRing not feasible?

A.
An equal amount of working and protect bandwidth is needed per span.

B.
Standards have not yet been defined for STM-1 MS-SPRings.

C.
There is not enough bandwidth in an STM-1 ring to justify MS-SPRing configuration.

D.
DCC bandwidth is not large enough to handle K1/K2 processing.

E.
Switch times would exceed 50ms on an STM-1 MS-SPRing.