IPS Policy Between 2 Trusted Networks

Hi Farzan, This is a tricky scenario. If you've enough security measures taken to ensure the VPN zone machines are secure, You can probably get away without keeping any policy. I would suggest creating a custom IPS policy and include the signatures according to your resources which are being accessed.

So, you suggest me to keep the IPS policy between Trusted Zones.

If you have control over both Zones and they're properly secured, Then it'll be okay if you don't apply any IPS policy between them. But in case if any attack originates in between trusted zones, then you won't be able to detect them on the Gateway level.