S6812 M-LAG问题 聚合端口连接备设备的对端端口down问题

两台华三的6812做M-LAG，下联的是思科的设备

端口聚合，出现端口updown并且ping出现丢包延时

出现updown时候主设备出现以下告警：

M-LAG/6/MLAG_IFEVT_PEERIF_NOSELECTED: Peer M-LAG interface in M-LAG group 34 does not have Selected member ports.

M-LAG/6/MLAG_IFEVT_PEERIF_SELECTED: Peer M-LAG interface in M-LAG group 34 has Selected member ports.

备设备出现以下：

LAGG/6/LAGG_INACTIVE_OPERSTATE: Member port XGE1/0/34 of aggregation group BAGG34 changed to the inactive state, because the peer port did not have the Synchronization flag.

 IFNET/5/LINK_UPDOWN: Line protocol state on the interface Ten-GigabitEthernet1/0/34 changed to down.

M-LAG/6/MLAG_IFEVT_MLAGIF_NOSELECTED: Local M-LAG interface Bridge-Aggregation34 in M-LAG group 34 does not have Selected member ports because the aggregate interface went down. Please check the aggregate link status.

STP/6/STP_NOTIFIED_TC: Instance 0's port Bridge-Aggregation34 was notified a topology change.

对端思科设备端口连接备设备的端口直接down.

请问这种情况应该如何排查，谢谢。