Why Does TCP Services Are Interrupted When Quick Session Backup Is Enabled in Case of Inconsistent Forward and Return Paths?
In case of inconsistent forward and return paths, the synchronization may fail or be delayed due to traffic bursts, result in service delay or interruption. For example, one firewall forwards TCP SYN packets, and the other forwards TCP ACK packets. If the session table is not synchronized, ACK packets may be discarded.
If this condition poses great impacts on services, disable stateful inspection on the firewall.