GTP-U Error Handling Procedure

This section describes the call flow associated with the GTP-U error handling procedure for the 4G sessions.

GTP-U Error Indication Handling Call Flow
GTP-U Error Handling Call Flow Description
StepDescription

1

S-GW sends GTP-U Error Indication towards UPF, indicating the bearer with the failed bearer ID.

2

After receiving GTP-U error indication, the UPF sends PFCPSessionReport towards SMF along with the failed bearer ID.

3a and 3b

The SMF sends PFCPSessionReport Success message and N4 Session Modification Request for dropped packet towards the UPF.

4

The UPF sends N4 Session Modification Response to the SMF.

5

The SMF sends Delete Bearer Request towards S-GW along with TEID, EBI, and cause.

6

The S-GW sends Delete Bearer Response towards SMF along with TEID, EBI, and cause as request accepted.

7a

If the TEID is a dedicated bearer, then the SMF sends N4 Session Modification Request with Delete PDR.

7b

The UPF sends N4 Session Modification Response.

8a

If it is a default bearer, the SMF sends N4 Session Release Request.

8b

The UPF sends N4 Session Release Response.

9a

The SMF sends Charging Data Terminate Request towards CHF.

9b

The CHF responds with Charging Data Terminate Response.

10a

The SMF sends SMPolicyControl Update Request towards PCF.

10b

The PCF sends SMPolicyControl Update Response to the SMF.