Cross Session Inspection (XSI) is a technology specially developed for mobile OSS and based on Cross Packet Inspection (XPI). It is sometimes also referred as "Session Inheritance".
This technology is achieving a complete session reassembly (XPI) and matching with other relevant sessions (XSI).
For example, a streaming user session is composed of many controls and data sessions (GTP-C + RTCP + RTSP + RTP sessions) which all need to be reassembled to get a full overview and understanding on how the service performs from the user's perspective.
A MMS user session is composed of one GTP-C and one MMSE session.
The process is as follow: the DPI engine start by analyzing the whole data flow inside the core network using Cross Packet Inspection (XPI) to link packets belonging to the same session and then uses the Cross Session Inspection (XSI) technology to link the sessions belonging to the same user session.
