Type of loopback
Software loopback: set via NMS;
Hardware loopback: set using tail fiber and self-loop cable manually.
Inloop: route signals from XC back to XC;
Outloop: route signals away from XC back to interface port.
SDH NE equipment
Line
Inloop
Outloop
Tributary
Loopback Operation
Outloop
Inloop
Tributary
Tributary
Line
Line
Tributary
SDH NE equipment
Inloop Non-loopback Outloop
Line
Tributary
32