Modification of the Default APN

Question

an UE is successfully registered and connected.
The HSS generates an S6a-IDR message to the MME including APN-Configuration-Profile with the the following information:
All-APN-Configurations-Included-Indicator = 1 (The APN list is complete)
One APN-Configuration containing an updated Default-APN.

Will the MME terminate all ongoing Data-sessions and attempt the creation of a new GTP Tunnel with the updated default-APN?
What will happen of the creation of the "New default-APN" GTP Tunnel fail?
Does the UE remain registered in the Network with no Data service?

Answer 1

Not sure but I think, MME will initiate network initiated detach procedure with the type of detach (re-attach) as the default APN itself has been changed.

Answer 2

On going Default bearer wont be delated until UE is not detached from network. That default bearer gives UE a always on connectivity with network and answer for your question is UE will be connected with network with data services.
For dedicated bearer mobile can trigger request or external application can trigger request which has better QOS than existing bearer.