Why is an STM-1 2F-MS-SPRing NOT feasible？（）

• A、 An equal amount of working and protect bandwidth is required.
• B、 DCC bandwidth is not large enough to handle K1/K2 processing.
• C、 Switch times would exceed 50 ms for an STM-1 MS-SPRing ring.
• D、 There is not enough bandwidth in an STM-1 ring to justify MS-SPRing protection.