A fault on the access-uplink port brings down all access ports with services independent of the encapsulation type of the access port (null, dot1q, or QinQ), that is, support Link Loss Forwarding (LLF). A fault propagated from the access-uplink port to access ports is based on configuration. A fault is propagated only in a single direction from the access-uplink port to access port.
A fault on the access-uplink port is detected using Loss of Signal (LoS) and EFM-OAM.
The following figure shows local fault propagation.
Figure: Local fault propagation
