Fortigate Vm Sizing Azure

| Family | Example Size | vCPUs | Memory | Best For | | :--- | :--- | :--- | :--- | :--- | | D-Series v5 (Dsv5) | Standard_D2s_v5 | 2 | 8 GB | General purpose – ideal for most. High CPU perf, fair price. | | D-Series v4 (Dsv4) | Standard_D4s_v4 | 4 | 16 GB | Mature, widely available, good for mid-range. | | F-Series (Fsv2) | Standard_F4s_v2 | 4 | 8 GB | CPU-optimized – excellent for IPsec VPN termination. | | E-Series (Esv5) | Standard_E4s_v5 | 4 | 32 GB | Memory-heavy – only needed for huge session tables (>2M). | | B-Series (Burstable) | Standard_B2s | 2 | 4 GB | NOT recommended for production – CPU credits run out quickly. |

Avoid: Any -as v4 sizes (they have less network acceleration) and older A-series VMs. fortigate vm sizing azure

If you are planning a deployment, follow this rough estimation guide: | Family | Example Size | vCPUs |

| Estimated Traffic Throughput | Recommended VM Tier (Approx) | vCPU / RAM | Notes | | :--- | :--- | :--- | :--- | | < 500 Mbps | Standard D2s_v5 | 2 vCPU / 8GB | Good for VPN hub or small spoke. | | 1 - 2 Gbps | Standard D4s_v5 | 4 vCPU / 16GB | Common mid-size hub. Enable Accelerated Networking. | | 3 - 5 Gbps | Standard D8s_v5 | 8 vCPU / 32GB | Ideal for heavy inspection/UTM. | | > 5 Gbps | Standard D16s_v5 or Fxs_v4 | 16+ vCPU | Check Azure bandwidth caps carefully here. | Example : Need 2 Gbps clean + SSL

My Advice: Start with a D-series v5 instance. They offer the best balance of CPU performance, network bandwidth credits, and cost. Deploy active-passive (AP) clustering via Azure Load Balancer for HA, and leverage the "Usage" graphs in the Azure Portal to verify if your CPU or Network Out metrics are hitting the ceiling.

1. Define required throughput (clean traffic) → ______ Gbps
2. Multiply by 1.5x (future growth) → ______ Gbps
3. Add inspection factor:
   - No inspection: x1.0
   - Basic firewall + NAT: x1.2
   - +IPS: x1.5
   - +SSL inspection: x2.0
   → Effective required Gbps = ______
4. Match to Azure VM size from table in section 3
5. Check license SKU supports that throughput
6. Add 20% vCPU/RAM overhead if using:
   - SSL deep inspection
   - 50+ IPsec tunnels
   - Explicit web proxy
7. Final VM size = ______

Example:
Need 2 Gbps clean + SSL inspection = 4 Gbps effective → D8s v3 + FG-VM04 license.