Introduction: The Complexity of Virtual Firewalls in the Cloud Migrating from a physical firewall appliance to a virtual firewall in Microsoft Azure is not a simple 1:1 core-to-core replacement. In the physical world, sizing was governed by ASIC acceleration and fixed port speeds. In Azure, your FortiGate VM (Fortinet’s Virtual Next-Generation Firewall) runs on shared or dedicated infrastructure, where CPU credits, RAM speed, and network latency are dynamic variables.
Need a sizing spreadsheet? Fortinet offers a free “Azure Sizing Calculator” on their support portal. Or, use the open-source fortinet-sizer tool on GitHub. fortigate vm sizing azure
An undersized FortiGate leads to packet drops, high latency, and VPN reconnections. An oversized VM wastes hundreds or thousands of dollars per month on idle vCPUs. Introduction: The Complexity of Virtual Firewalls in the
Finally, test with your real traffic – not synthetic UDP floods. Cloud networking behaves differently on Tuesday at 2 PM vs. Friday at 5 PM. Use FortiView’s “Top Threats” and “Top Applications” to refine your sizing every quarter. Need a sizing spreadsheet