5800ei mstp端口状态变化

内网的核心交换机收到了拓扑变化之后，上面的正在使用的接口全部变成了discarding状态，过了一会之后又变成forwarding状态了。

各位，这种一般是什么原因引起的？大概断了30秒

%May 3 00:43:10:070 2000 S5800 MSTP/6/MSTP_NOTIFIED_TC: Instance 0's port Bridge-Aggregation1 was notified of a topology change. %May 3 00:44:06:748 2000 S5800 MSTP/6/MSTP_DISCARDING: Instance 0's port GigabitEthernet1/1/1 has been set to discarding state. %May 3 00:44:06:748 2000 S5800 MSTP/6/MSTP_DISCARDING: Instance 0's port GigabitEthernet1/1/11 has been set to discarding state. %May 3 00:44:06:749 2000 S5800 MSTP/6/MSTP_DISCARDING: Instance 0's port GigabitEthernet1/1/13 has been set to discarding state. %May 3 00:44:06:749 2000 S5800 MSTP/6/MSTP_DISCARDING: Instance 0's port GigabitEthernet1/1/14 has been set to discarding state. %May 3 00:44:06:750 2000 S5800 MSTP/6/MSTP_DISCARDING: Instance 0's port GigabitEthernet1/1/15 has been set to discarding state. %May 3 00:44:06:750 2000 S5800 MSTP/6/MSTP_DISCARDING: -Slot=2; Instance 0's port GigabitEthernet2/1/15 has been set to discarding state. %May 3 00:44:06:798 2000 S5800 MSTP/6/MSTP_NOTIFIED_TC: Instance 0's port Bridge-Aggregation1 was notified of a topology change. %May 3 00:44:08:835 2000 S5800 MSTP/6/MSTP_NOTIFIED_TC: Instance 0's port Bridge-Aggregation1 was notified of a topology change. %May 3 00:44:09:538 2000 S5800 MSTP/6/MSTP_NOTIFIED_TC: Instance 0's port Bridge-Aggregation1 was notified of a topology change. %May 3 00:44:11:847 2000 S5800 MSTP/6/MSTP_NOTIFIED_TC: Instance 0's port Bridge-Aggregation1 was notified of a topology change. %May 3 00:44:36:077 2000 S5800 MSTP/6/MSTP_FORWARDING: -Slot=2; Instance 0's port GigabitEthernet2/1/15 has been set to forwarding state. %May 3 00:44:36:749 2000 S5800 MSTP/6/MSTP_FORWARDING: Instance 0's port GigabitEthernet1/1/1 has been set to forwarding state. %May 3 00:44:36:750 2000 S5800 MSTP/6/MSTP_FORWARDING: Instance 0's port GigabitEthernet1/1/11 has been set to forwarding state. %May 3 00:44:36:750 2000 S5800 MSTP/6/MSTP_FORWARDING: Instance 0's port GigabitEthernet1/1/13 has been set to forwarding state. %May 3 00:44:36:751 2000 S5800 MSTP/6/MSTP_FORWARDING: Instance 0's port GigabitEthernet1/1/14 has been set to forwarding state. %May 3 00:44:36:752 2000 S5800 MSTP/6/MSTP_FORWARDING: Instance 0's port GigabitEthernet1/1/15 has been set to forwarding state. %May 3 00:44:38:653 2000 S5800 MSTP/6/MSTP_NOTIFIED_TC: Instance 0's port Bridge-Aggregation1 was notified of a topology change. %May 3 00:44:40:960 2000 S5800 MSTP/6/MSTP_NOTIFIED_TC: Instance 0's port Bridge-Aggregation1 was notified of a topology change. %May 3 00:44:43:562 2000 S5800 MSTP/6/MSTP_NOTIFIED_TC: Instance 0's port Bridge-Aggregation1 was notified of a topology change. %May 3 00:44:45:933 2000 S5800 MSTP/6/MSTP_NOTIFIED_TC: Instance 0's port Bridge-Aggregation1 was notified of a topology change.