Multi PDN Multi-trace
For a multi-PDN call, when you start the MonSub with Multi-trace=OFF, then it traces the only one PDN as a part of that MonSub session. When a new PDN is initiated, then existing PDN tracing stops and new PDN tracing starts. For it to happen, first the new PDN tracing is started and then the existing PDN tracing is stopped. Hence, new PSN and session manager sub-session ID is allocated.
For a multi-PDN call, when you start the MonSub with Multi-trace=ON, it traces the new PDN as part of new fastpath tracing session (that is MonSub session). Hence, after tracing the four PDN, MonSub CLI shows max tracing session reached. Tracing each PDN takes place as a separate MonSub session.