SMF Initiated Detach Procedure
SMF receives a request for session release through one of the following methods:
-
Clear Subscriber
-
GTP Path Failure
-
Peer Restart
-
Absolute Session Timeout
-
Cp-idle Timeout
The following call flow illustrates the procedure of an E-UTRAN network (SMF) initiated detach.
| Step | Description |
|---|---|
| 1 |
SMF sends N4 PFCP Session Modification Request to UPF with FARs having apply action set to Drop. |
| 2 |
UPF sends N4 PFCP Session Modification Response to SMF. |
|
3 |
SMF sends Delete Bearer Request to S-GW. |
|
4 |
S-GW sends Delete Bearer Request to MME. |
|
5 |
MME sends Delete Bearer Response to S-GW. |
|
6 |
S-GW sends Delete Bearer Response to SMF. |
|
7 |
SMF sends N4 PFCP Session Deletion Request to UPF to release N4 session. |
|
8 |
UPF sends N4 PFCP Session Deletion Response to SMF. |
|
9 |
SMF sends Radius Accounting Request Stop to AAA server to release the accounting session. |
|
10 |
AAA server sends Radius Accounting Response to SMF. |
|
11 |
SMF sends Gx Credit Control Request Terminate to OCS to release the Gy session. |
|
12 |
OCS sends Gx Credit Control Answer Terminate to SMF. |
|
13 |
SMF sends Gx Credit Control Request Terminate to PCRF to release the Gx session. |
|
14 |
PCRF sends Gx Credit Control Answer Terminate to SMF. |