Client---internal network -----S9300-1----C7606-----DCN network-----Server
Between the S9300 and C7606 interact via OSPF routing, and packet dropped after switchover.
Since the ping without the business source address to server is normal, there is no proven link quality problem.
And the problem should still be out on the routings.
And when check ospf error found Duplicate ack continues to grow, then I think this cutover Router-id has changed, the original is the interface address , now turned into a loopback address, suspected router-id routing oscillation caused by the conflict, replaced Router-id testing business back to normal, and delete loopback address, found also PING, to prove the existence of an address conflict issues;
1, VRRP double masters or problems caused by MSTP abnormalities;
2, IP address conflicts ;
3, other issues;