Section: 6.4.3.6 Abnormal cases on the network side
Content: The following abnormal cases can be identified: a) Expiry of timer T3486: On the first expiry of the timer T3486, the MME shall resend the MODIFY EPS BEARER CONTEXT REQUEST and shall reset and restart timer T3486. This retransmission is repeated four times, i.e. on the fifth expiry of timer T3486, the MME shall abort the procedure and enter the state BEARER CONTEXT ACTIVE. The MME may continue to use the previous configuration of the EPS bearer context or initiate an EPS bearer context deactivation procedure. b) Collision of UE requested PDN disconnect procedure and EPS bearer context modification: When the MME receives a PDN DISCONNECT REQUEST message during an EPS bearer context modification procedure, and the EPS bearer to be modified belongs to the PDN connection the UE wants to disconnect, the MME shall terminate the EPS bearer context modification procedure locally, release any resources related to this procedure and proceed with the PDN disconnect procedure. c) Collision of UE requested bearer resource modification procedure and EPS bearer context modification procedure: If the MME receives a BEARER RESOURCE MODIFICATION REQUEST message during the EPS bearer context modification procedure and the EPS bearer indicated in the BEARER RESOURCE MODIFICATION REQUEST message is the EPS bearer that the network had requested to modify, the network shall ignore the BEARER RESOURCE MODIFICATION REQUEST message received in the state BEATER CONTEXT MODIFY PENDING. The network shall proceed with the EPS bearer modification procedure as if no BEARER RESOURCE MODIFICATION REQUEST message was received from the UE.