Does S1AP disconnection affects user traffic?

Question

Lets take UE which successfully establishes EPC bearer and started sending user data via GTP-U tunnel.

Will that user traffic flow be affected in case we have some issues with S1AP interface (for example network links down or something like that)?

And how will S1-U tunnels be affected when S1AP connection will be established again?

Answer 1

The UE will enter into ECM-IDLE state when its signalling connection to the MME has been released or broken. This release or failure is explicitly indicated by the eNodeB to the UE or detected by the UE

There will be no UE context in E-UTRAN for the UE in the ECM-IDLE state. There is no S1_MME and no S1_U connection for the UE in the ECM-IDLE state. So in short user's traffic will be affected.