guidance on networking strategy for KVM

[opticalc]

Im not quite sure when I would need to create a bridge. or what types of interfaces to put into my VM host. Then on what type of drive to tell it to use.

My goal is to use a dual nic PC as a bare metal KVM server. Where 1 interface goes to cable modem and the other interface goes to my internal networks ethernet switch.

pfsense will run in a VM, and it needs 2 network connections. Pfsense will use DHCP for its WAN, and on its LAN it will run a DHCP server for my internal network.

Im not quite sure of the general strategy that is best for creating bridges and giving interfaces to my VMs, and which driver to tell the VM it has.

I just got the latest centos7 dvd installed and am running through some kvm tutorials.

Can I get some guidance please?