Stand-Alone User Plane Node Traffic Monitoring

In Stand-Alone User Plane Node (UPN) traffic monitoring, the UPN processes the subscriber information that is extracted from the Packet Forwarding Control Protocol (PFCP) packets and correlates with the GTP-u traffic without the CPN.

PFCP (Packet Forwarding Control Protocol) is a 3GPP Protocol that is communicated on the Sxa, Sxb, N4 Interface between the Control Plane (CP) elements and User Plane (UP) elements. The CP element programs the UP element with policies on how to forward packets.

PFCP allows an optional Informational Elements (IE) that contains SUPI/IMSI, PEI/IMEI, GPSI/MSISDN information of the Subscriber during PFCP Session Establishment Request. If your network enables these optional information elements, then you can use the Stand-Alone User Plane Node traffic monitoring.

The UPN performs the following activities in the Stand-Alone mode:

  • Processes the PFCP session establishment request and extracts the SUPI/IMSI, PEI/IMEI, GPSI/MSISDN User IP and TEID for both end points. The information in the PFCP traffic is used to populate the UPN's session table.
  • Correlates GTP-U traffic based on the subscriber information from PFCP. GTP-U look up is correlated based on the IP and TEID .

  • When UPN standalone mode is used, forward lists are limited to IMSI/SUPI only, and flowsampling maps for filtering or sampling are limited to IMSI/SUPI and IMEI/PEI. You will not be able to use any other CP fields for filtering or sampling, including APN, DNN, QCI, 5QI, ECGI, NCGI, NSI.

The following diagram explains the functioning of UPN in Stand-alone mode:

Rules and Notes

  • You can create a Stand-Alone UPN traffic monitoring session only when there is atleast SUPI/IMSI in the user fields.

  • The UPN only supports PFCP traffic from Sxa for LTE, N4 for 5G. GTP and 5G maps are required to forward traffic.

  • The UPN determines if PFCP is from the N4 interface if it has QFI information.

Configure Stand-Alone User Plane Node Traffic Monitoring

To configure Stand-Alone User Plane Node Traffic Monitoring, refer to Configuration of CUPS using Ansible

Note:   You must enable the stand-alone mode in UPN while creating the solution in Ansible. Once the stand-alone mode is enabled, UPN cannot connect with the CPN, and you cannot the change the mode. To change the mode, you need to delete the UPN from the solution and add a new one .