Ericsson MINI-LINK TN R3 ETSI Technical Description page 57

3.9.5 Enhanced Equipment Protection
Enhanced Equipment Protection (EEP) (optical) protects the STM-1 line on
MMU2 E/F 155. Through a Small Form Factor Pluggable (SFP), see Section
7.3 on page 128, plus an external optical combiner/splitter, see Figure 49 on
page 51, the STM-1 input/output are protected; while one MMU Tx laser is
transmitting, the other one must be switched off (Laser Shut Down). See also
MMU2 F 155 in Section 4.2 on page 61.
Figure 49
4/1555-CSH 109 32/1-V1 Uen B 2007-09-14
Optical splitter/combiner
Basic Node
9358
51