hi,
and welcome to the forums.
Basically, you have just to create one policy to allow traffic from port1 to port2. Routing is done automatically because the FGT knows about both networks.
Go to
Policy > Policy > Policy
Create New
source interface: port1
source addr: LAN_172_1
dest. interface: port2
dest. addr: LAN_172_2
schedule: always
service: ALL
action: ACCEPT
NAT: do not check
log: check
Done.
Place this policy above other policies which are less specific, ie. policy port1->wan1. Test.
This will not apply any UTM features, like AV or IPS. You may want to add this later.
This is fairly basic which tells me you' re new to Fortigates and/or firewalls in general. A good starting point for getting to know FortiOS is here
http://docs.fortinet.com
especially the FortiOS Handbook (the complete reference) and the Cookbook (a lot of practical recipes, step-by-step). Recommended.
Ede Kernel panic: Aiee, killing interrupt handler!