Combining Multiple Ports as a Single interface

You want each firewall to have three IPs? Or you want three firewalls, each with a unique IP? (In the latter case, you don't need to combine multiple ports.)

Are you trying to get redundancy? Perhaps an High Availability (HA) setup would serve you better?

Thanks for the response.

I just want three firewalls in a network.

I am unable to assign Ip's of same network to two different interfaces.

Thanks for the response.

I just want three firewalls in a network.

I am unable to assign Ip's of same network to two different interfaces.

It seems like the issue of multiple firewalls is completely distinct from one of those firewalls having two ports connected to the same subnet, so I would remove any reference to multiple firewalls. It doesn't seem to make any sense to have multiple firewalls on the same network, unless you're doing High Availability, but that's your choice.

So you want a single firewall to have two ports on the same subnet? What are you wanting to accomplish with this? That makes a difference what you'd need to do.