SxDemuxMgr
In distributed architecture of UP/UPF, sessions (Sxa or N4) run on different SessMgr instances. To support collapsing/converging the sessions to a single SessMgr, the SessMgr instance is selected by both sessions during establishment.
At SxDemux, when Sx Establishment Request (Sxa or N4) is received for selecting the SessMgr instance, it’s parsed for finding the SessMgr instance from remote F-TEID, where corresponding sessions (N4 or Sxa respectively) are established. The F-TEID, that contains the Tunnel Identifier embedded with SessMgr instance, is extracted.
UPF also maintains IMSI entry at SxDemux. IMSI entry has information of SessMgr ID where the current session is hosted. When Converged Datapath feature is enabled, on receiving Sx Session Establishment Request, SxDemux first tries to find the SessMgr ID using F-TEID. If F-TEID is not present, IMSI lookup is done. If both F-TEID and IMSI is not present, then SxDemux won't select the same SessMgr ID for Sxa/N4 leg.