Is there any SNMP mib options to show traffic details per session instead of interface? I'm using PRTG for some basic monitoring of an SRX340 and have bandwidth utilization per interface working well. Is it jflow instead of SNMP?
SNMP does not expose the session or flow level detail.
Jflow would be an option if prtg supports that you can configure the flow records to be pushed to that collector. If not there are several open source flow collectors you might use to collect and report the information.