So you are saying you have 4 modules.
You have 3 options
- have the all facing your traffic from the outside, and being able to "firewall" more traffic"
- have 2 failover active/standby FWSM pairs. You can do less traffic but you have redundancy.
- have 2 active/active FWSM pairs. All 4 can pass traffic and you have redundancy but if the traffic is high and one fails you might lose trafffic.
I hope it helps.
You can also check the config guide for failover to understand the differences.
PK