UPSR protection switching is ini
题目
UPSR protection switching is initiated by （）, while BLSR is initiated by （）.
- A、the K1 SONET byte； the K2 SONET byte
- B、the K2 SONET byte；the K1 SONET byte
- C、transmitter switching；receiver detection
- D、Line Overhead bytes；Path Overhead bytes
- E、Path Overhead bytes；Line Overhead bytes
