This article describes the prerequisites and steps needed to replicate dynamic routing protocol routes (OSPF, BGP, RIP) to your passive firewall in an NSRP cluster
Procedure to follow
Starting in ScreenOS 6.0.0r1, you can use the command from ssh terminal of your firewall
set nsrp rto-mirror route
Which will replicate all dynamic routes from the active primary member to the backup NSRP member. Without this command, if a fail over occurs, it may take several seconds for the dynamic adjacencies to re-establish, and sessions can be interrupted or dropped as a result.