1.12 Paging以及由网络侧触发的Service Request流程

hycl5410

看一眼这个 TS23.401 a80

5.3.4.2        Handling of abnormal conditions in UE triggered Service Request
Under certain conditions, the current UE triggered Service Request procedure can cause unnecessary Downlink Packet Notification messages which increase the load of the MME.
This can occur when uplink data sent in step 6 causes a response on the downlink which arrives at the Serving GW before the Update Bearer Request message, step 8. This data cannot be forwarded from the Serving GW to the eNodeB and hence it triggers a Downlink Data Notification message.
If the MME receives a Downlink Data Notification after step 2 and before step 9, the MME shall not send S1 interface paging messages. However, across all the UEs on that MME, the MME shall monitor the rate at which these events occur. If the rate becomes significant (as configured by the operator) and the MME's load exceeds an operator configured value, the MME shall indicate "Delay Downlink Packet Notification Request" with parameter D to the Serving Gateway, where D is the requested delay given as an integer multiple of 50 ms, or zero. The Serving GW then uses this delay in between receiving downlink data and sending the Downlink Data Notification message.
NOTE 1:        A low rate of reception of Downlink Data Notifications between steps 2 and 9 should be considered a normal circumstance, e.g. due to the chance that a UE Terminating call/session is initiated at roughly the same time as the UE triggered Service Request procedure.
NOTE 2:        It is recommended that this rate is determined over 60 second periods.

不过没抓包的话不能确定。建议以后这样的事直接上抓包问问题。
不但要分析问题，还得猜“这个问题是啥”