. , . (Multiplex Section Protection - MSP). , SDH ( BIP) . (APS) . . APS 1+1 1:n
1 2 . 1 . 2 , APS 1:n, MSP , APS. MSP . , SDH - " " (.1) (.1b). , . . , - . .
50 .
.1. SDH.
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(.2) SDH SDH (155 622 /). - 1+1, SMUX /: - , .
. 2. "" c 1+1.
SDH.
SDH .