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

Step | Description |
---|---|
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. |