Question: What action does an SGSN take when detecting a restart in a GGSN for activated PDP contexts, and what is the subsequent request to the MS?
Option 1: The SGSN deletes all activated PDP contexts and notifies the MS of the deletion.
Option 2: The SGSN modifies all activated PDP contexts to a dormant state without notifying the MS.
Option 3: The SGSN keeps all activated PDP contexts active, assuming the GGSN restart is transparent to them.
Option 4: The SGSN deactivates all these PDP contexts and requests the Mobile Station (MS) to reactivate them.
Explanation: Upon detecting a GGSN restart affecting activated PDP contexts, the SGSN must take corrective action to maintain network integrity. Deactivating the affected PDP contexts ensures consistency across the network post-restart. Requesting the MS to reactivate these contexts allows for the re-establishment of necessary connections, ensuring minimal disruption to services. This approach balances the need for network stability with service continuity, highlighting the SGSN's role in managing and adapting to changes in the telecom infrastructure.