Question: Which protocol(s) are mandated for transporting and routing subscription/notification related signalling over the CSC-5 reference point between an MC Service Server and a Configuration Management Server?
Option 1: HTTP-1 and HTTP-2 exclusively
Option 2: SIP-2 only, with optional fallback to HTTP-1 for non-critical signals
Option 3: Both HTTP-1 and SIP-2, depending on the type of subscription
Option 4: SIP-2 and SIP-3, with SIP-3 used when servers are served by different SIP cores
Explanation: According to the specifications for the CSC-5 reference point, subscription/notification related signalling requires the use of SIP protocols. Specifically, SIP-2 is mandated, while SIP-3 is additionally utilized in scenarios where the MC Service Server and the Configuration Management Server are connected through different SIP cores, ensuring flexibility and compatibility across varying network architectures.