10.3 Timers of 5GS session management

24.5013GPPNon-Access-Stratum (NAS) protocol for 5G System (5GS)Release 17Stage 3TS

Timers of 5GS session management are shown in table 10.3.1 and table 10.3.2.

NOTE: Timer T3396 is defined in 3GPP TS 24.008 [12].

Table 10.3.1: Timers of 5GS session management – UE side

TIMER NUM.

TIMER VALUE

STATE

CAUSE OF START

NORMAL STOP

ON
THE
1st, 2nd, 3rd, 4th EXPIRY (NOTE 1)

T3580

NOTE 4

NOTE 5

16s

In WB-N1/CE mode, 24s

PDU SESSION ACTIVE PENDING

Transmission of PDU SESSION ESTABLISHMENT REQUEST message

PDU SESSION ESTABLISHMENT ACCEPT message received or

PDU SESSION ESTABLISHMENT REJECT message received or

PDU SESSION ESTABLISHMENT REQUEST received in a DL NAS TRANSPORT message with 5GMM cause #22, #28, #65. #67, #69, #90, #91 or #92

Retransmission of PDU SESSION ESTABLISHMENT REQUEST message

T3581

NOTE 4

NOTE 5

16s

In WB-N1/CE mode, 24s

PDU SESSION MODIFICATION PENDING

Transmission of PDU SESSION MODIFICATION REQUEST message

PDU SESSION MODIFICATION COMMAND message with the same PTI is received or PDU SESSION MODIFICATION REJECT message received or

PDU SESSION MODIFICATION REQUEST received in a DL NAS TRANSPORT message with 5GMM cause #22, #28. #67, #69, or #90

Retransmission of PDU SESSION MODIFICATION REQUEST message

T3582

NOTE 4

NOTE 5

16s

In WB-N1/CE mode, 24s

PDU SESSION INACTIVE PENDING

Transmission of PDU SESSION RELEASE REQUEST message

PDU SESSION RELEASE COMMAND message with the same PTI is received or PDU SESSION RELEASE REJECT message received

Retransmission of PDU SESSION RELEASE REQUEST message

T3583

Default 1 min.

NOTE 2

PDU SESSION ACTIVE

UE creates or updates a derived QoS rule

UE deletes the derived QoS rule (see subclause 6.2.5.1.4.5)

On 1st expiry: Deletion of the derived QoS rule

T3584

NOTE 3

PDU SESSION ACTIVE PENDING

PDU SESSION MODIFICATION PENDING

PDU SESSION ACTIVE or PDU SESSION INACTIVE PENDING

PDU SESSION ESTABLISHMENT REJECT, PDU SESSION MODIFICATION REJECT, or PDU SESSION RELEASE COMMAND received with 5GSM cause #67 and with a timer value for T3584

PDU SESSION ESTABLISHMENT REQUEST, or PDU SESSION MODIFICATION REQUEST received in a DL NAS TRANSPORT message with 5GMM cause #67 and with a timer value for T3584 (see subclause 5.4.5.3.3)

PDU SESSION RELEASE COMMAND (see NOTE 6) or PDU SESSION MODIFICATION COMMAND or PDU SESSION AUTHENTICATION COMMAND or DEREGISTRATION REQUEST with the re-registration type "re-registration required"

None

T3585

NOTE 3

PDU SESSION ACTIVE PENDING

PDU SESSION MODIFICATION PENDING

PDU SESSION ACTIVE or PDU SESSION INACTIVE PENDING

PDU SESSION ESTABLISHMENT REJECT, PDU SESSION MODIFICATION REJECT, or PDU SESSION RELEASE COMMAND received with 5GSM cause #69 and with a timer value for T3585

PDU SESSION ESTABLISHMENT REQUEST, or PDU SESSION MODIFICATION REQUEST received in a DL NAS TRANSPORT message with 5GMM cause #69 and with a timer value for T3585(see subclause 5.4.5.3.3)

PDU SESSION RELEASE COMMAND (see NOTE 6) or PDU SESSION MODIFICATION COMMAND or PDU SESSION AUTHENTICATION COMMAND or DEREGISTRATION REQUEST with the re-registration type "re-registration required"

None

Back-off timer

defined in 3GPP TS 24.008 [12]

T3586
NOTE 4

NOTE 5

8s

In WB-N1/CE mode, 16s

PDU SESSION ACTIVE

REMOTE UE REPORT sent

REMOTE UE REPORT RESPONSE received

Retransmission of REMOTE UE REPORT

NOTE 1: Typically, the procedures are aborted on the fifth expiry of the relevant timer. Exceptions are described in the corresponding procedure description.

NOTE 2: The network may provide the value of this timer applicable to the derived QoS rules of a specific PDU session as RQ timer value in the PDU SESSION ESTABLISHMENT ACCEPT message and PDU SESSION MODIFICATION COMMAND message. The maximum value of the timer is 30 min. If the network indicates a value greater than the maximum value, then the UE shall use the maximum value.

NOTE 3: The value of this timer is provided by the network.

NOTE 4: In NB-N1 mode, then the timer value shall be calculated as described in subclause 4.18.

NOTE 5: In WB-N1 mode, if the UE supports CE mode B and operates in either CE mode A or CE mode B, then the timer value is as described in this table for the case of WB-N1/CE mode (see subclause 4.20).

NOTE 6: If the PDU SESSION RELEASE COMMAND message includes the Back-off timer value IE where the timer value indicates neither zero nor deactivated and the 5GSM cause is not #39, the UE then starts the timer with the value provided in the Back-off timer value IE after stopping the existing timer (see subclause 6.3.3.3).

NOTE 1: The back-off timer is used to describe a logical model of the required UE behaviour. This model does not imply any specific implementation, e.g. as a timer of timestamp.

NOTE 2: Reference to back-off timer in this section can either refer to use of timer T3396 or to use of a different packet system specific timer within the UE. Whether the UE uses T3396 as a back-off timer or it uses different packet system specific timers as back-off timers is left up to UE implementation.

Table 10.3.2: Timers of 5GS session management – SMF side

TIMER NUM.

TIMER VALUE

STATE

CAUSE OF START

NORMAL STOP

ON
THE
1st, 2nd, 3rd, 4th EXPIRY (NOTE 1)

T3590

NOTE 3

NOTE 4

15s

In WB-N1/CE mode, 23s

PROCEDURE TRANSACTION PENDING

Transmission of PDU SESSION AUTHENTICATION COMMAND message

PDU SESSION AUTHENTICATION COMPLETE message received

Retransmission of PDU SESSION AUTHENTICATION COMMAND message

T3591

NOTE 3

NOTE 4

16s

In WB-N1/CE mode, 24s

PDU SESSION MODIFICATION PENDING

Transmission of PDU SESSION MODIFICATION COMMAND message

PDU SESSION MODIFICATION COMPLETE message received or PDU SESSION MODIFICATION COMMAND REJECT message received

Retransmission of PDU SESSION MODIFICATION COMMAND message

T3592

NOTE 3

NOTE 4

16s

In WB-N1/CE mode, 24s

PDU SESSION INACTIVE PENDING

Transmission of PDU SESSION RELEASE COMMAND message

PDU SESSION RELEASE COMPLETE message received or

N1 SM delivery skipped indication received

Retransmission of PDU SESSION RELEASE COMMAND message

T3593

NOTE 3

NOTE 4

Default

60s

(NOTE 2)

PDU SESSION MODIFICATION PENDING

Reception of PDU SESSION MODIFICATION COMPLETE message for transmitted PDU SESSION MODIFICATION COMMAND message where the PDU SESSION MODIFICATION COMMAND message included 5GSM cause #39

PDU SESSION RELEASE REQUEST message received

Network-requested PDU session release procedure performed

NOTE 1: Typically, the procedures are aborted on the fifth expiry of the relevant timer. Exceptions are described in the corresponding procedure description.

NOTE 2: If the PDU Session Address Lifetime value is sent to the UE in the PDU SESSION MODIFICATION COMMAND message then timer T3593 shall be started with the same value, otherwise it shall use a default value.

NOTE 3: In NB-N1 mode, the timer value shall be calculated as described in subclause 4.18.

NOTE 4: In WB-N1 mode, if the UE supports CE mode B and operates in either CE mode A or CE mode B, then the timer value is as described in this table for the case of WB-N1/CE mode (see subclause 4.20).