Having a reliable internet connection is super critical for businesses these days. I mean, what would we do without it, right? Configuring ISP failover on your FortiGate firewall is like setting up a safety net, making sure you stay connected even when your primary internet service provider (ISP) decides to take an unexpected coffee break. This guide will walk you through the process, step by step, so you can keep your network up and running smoothly. Trust me, it's not as scary as it sounds!

Why You Need ISP Failover

Let's get real – internet outages happen. Whether it's due to maintenance, equipment failure, or some backhoe having a bad day and cutting your fiber optic line, these disruptions can seriously mess with your business. Imagine your customers can't reach your website, your employees can't access cloud services, or your transactions grind to a halt. Ouch! That's where ISP failover comes in to save the day.

ISP failover is all about automatically switching your internet traffic to a backup connection when your primary connection goes down. It's like having a spare tire for your car – you hope you never need it, but you'll be super grateful when you do. With a properly configured failover, your users won't even notice the switch, and your business can keep chugging along without interruption. Plus, it gives you peace of mind knowing you're prepared for the unexpected.

Benefits of ISP Failover:

• Business Continuity: Keep critical applications and services online, no matter what.
• Reduced Downtime: Minimize the impact of internet outages on your productivity and revenue.
• Improved Reliability: Ensure a more stable and dependable network connection.
• Enhanced User Experience: Provide seamless connectivity for your users, even during disruptions.
• Peace of Mind: Sleep better knowing your network is protected from internet outages.

So, if you're not already thinking about ISP failover, now's the time to start. It's an investment that can pay off big time in terms of uptime, productivity, and overall business resilience. Trust me, your future self will thank you!

Prerequisites

Before we dive into the configuration, let's make sure we have all our ducks in a row. Here's what you'll need to get started:

1. FortiGate Firewall: Obviously, you'll need a FortiGate firewall running FortiOS. This guide assumes you have basic familiarity with the FortiGate interface.
2. Two or More Internet Connections: You'll need at least two internet connections from different ISPs. This is the heart of the failover setup.
3. Static IP Addresses (Recommended): While not strictly required, using static IP addresses for your WAN interfaces will simplify the configuration and make troubleshooting easier. Dynamic IP addresses can work, but you'll need to use Dynamic DNS (DDNS) and adjust the configuration accordingly.
4. Network Diagram: Having a clear understanding of your network topology will be super helpful. Draw a diagram showing your FortiGate, ISPs, internal network, and any relevant devices.
5. Login Credentials: Make sure you have administrator access to your FortiGate firewall. You'll need this to make the necessary configuration changes.
6. Patience: Configuring ISP failover can sometimes be a bit tricky, so take your time, follow the steps carefully, and don't be afraid to consult the FortiGate documentation or online resources if you get stuck.

With these prerequisites in place, you'll be well-prepared to tackle the configuration process. Let's move on to the fun part!

Step-by-Step Configuration

Alright, let's get down to business and configure ISP failover on your FortiGate. I'll break it down into manageable steps so you can follow along easily.

Step 1: Configure WAN Interfaces

First things first, we need to configure your WAN interfaces, which are the connections to your ISPs. Here's how:

1. Log in to your FortiGate firewall using your administrator credentials.
2. Go to Network > Interfaces. Here, you'll see a list of your FortiGate's interfaces.
3. Edit your primary WAN interface (e.g., "wan1").
   • Set the Interface Name to something descriptive (e.g., "ISP1").
   • Set the Type to "WAN".
   • Choose the appropriate Addressing Mode (usually "Manual" for static IP or "DHCP" for dynamic IP).
   • Enter the IP Address, Netmask, and Gateway information provided by your ISP.
   • Enable Override DNS and enter the DNS server addresses provided by your ISP or use public DNS servers like Google DNS (8.8.8.8 and 8.8.4.4) or Cloudflare DNS (1.1.1.1 and 1.0.0.1).
   • Click OK to save the changes.
4. Repeat the process for your secondary WAN interface (e.g., "wan2").
   • Set the Interface Name to something descriptive (e.g., "ISP2").
   • Use the IP address, netmask, and gateway information from your second ISP.

Step 2: Configure Static Routes

Next, we need to configure static routes to tell the FortiGate how to reach the internet through each ISP. Here's how:

1. Go to Network > Static Routes.
2. Click Create New.
3. Create a static route for your primary ISP:
   • Set the Destination to 0.0.0.0/0 (this means any destination).
   • Set the Interface to your primary WAN interface (e.g., "ISP1").
   • Set the Gateway to the gateway address provided by your primary ISP.
   • Set the Distance to 1. This is the priority of the route. Lower numbers mean higher priority.
   • Click OK to save the route.
4. Create a static route for your secondary ISP:
   • Set the Destination to 0.0.0.0/0.
   • Set the Interface to your secondary WAN interface (e.g., "ISP2").
   • Set the Gateway to the gateway address provided by your secondary ISP.
   • Set the Distance to 2. This is important! Make sure the distance is higher than the primary ISP's route. This tells the FortiGate to use this route only when the primary route is unavailable.
   • Click OK to save the route.

Step 3: Configure DNS Servers

Now, let's make sure your FortiGate knows which DNS servers to use. This is usually configured on the WAN interfaces, but let's double-check.

1. Go to Network > Interfaces.
2. Edit your primary WAN interface (e.g., "ISP1").
3. Make sure Override DNS is enabled and the DNS server addresses are correct (either provided by your ISP or public DNS servers).
4. Repeat the process for your secondary WAN interface (e.g., "ISP2").

Step 4: Configure a Health Check

This is where the magic happens! We need to configure a health check to monitor the availability of your primary internet connection. If the health check fails, the FortiGate will automatically switch to the secondary connection.

1. Go to Network > SD-WAN. If you don't see SD-WAN, make sure it's enabled in System > Feature Visibility.
2. Click Create New and choose Health Check.
3. Configure the health check:
   • Set the Name to something descriptive (e.g., "ISP1 Health Check").
   • Set the Target to an IP address that's reliable and outside your network. Public DNS servers like Google DNS (8.8.8.8) or Cloudflare DNS (1.1.1.1) are good choices.
   • Set the Protocol to "Ping".
   • Adjust the Interval and Retry settings as needed. The default values are usually fine.
   • Click OK to save the health check.
4. Create another health check for your secondary ISP if you want to monitor its health independently. This is optional but recommended.

Step 5: Configure SD-WAN Rule

Now, we'll create an SD-WAN rule to use the health check and define how traffic should be routed based on the availability of the internet connections.

1. Go to Network > SD-WAN.
2. Click Create New and choose SD-WAN Rule.
3. Configure the SD-WAN rule:
   • Set the Name to something descriptive (e.g., "ISP Failover Rule").
   • Set the Source to your internal network (e.g., 192.168.1.0/24).
   • Set the Destination to 0.0.0.0/0 (any destination).
   • Under Members, add your two WAN interfaces (e.g., "ISP1" and "ISP2").
   • For the Strategy, choose "Best Quality".
   • Under Health Check, select the health check you created for your primary ISP (e.g., "ISP1 Health Check").
   • Enable Status Check.
   • Click OK to save the rule.

Testing the Failover

Alright, you've done the hard work! Now it's time to test your failover configuration to make sure it's working as expected.

1. Simulate a primary ISP outage: The easiest way to do this is to physically disconnect the primary WAN interface from your FortiGate or shut down the connection on the ISP's side (if you have access to that).
2. Monitor your network traffic: Use the FortiGate's real-time traffic monitor (Go to FortiView > Sources) or ping a public IP address (like 8.8.8.8) from a device on your internal network. You should see the traffic automatically switch to the secondary ISP.
3. Check the FortiGate logs: Go to Log & Report > Events and filter for events related to SD-WAN or interface status changes. You should see logs indicating that the primary interface went down and the traffic was switched to the secondary interface.
4. Reconnect the primary ISP: Once you've verified that the failover is working, reconnect the primary WAN interface. The traffic should automatically switch back to the primary ISP once it's available again.

If everything works as expected, congratulations! You've successfully configured ISP failover on your FortiGate firewall. If you encounter any issues, double-check your configuration, consult the FortiGate documentation, or seek help from online forums or Fortinet support.

Additional Tips and Considerations

Here are a few extra tips and things to keep in mind when configuring ISP failover:

• Load Balancing: Instead of just using one ISP as a backup, you can configure load balancing to distribute traffic across both ISPs simultaneously. This can improve performance and utilize your bandwidth more efficiently. Look into the "Weighted Round Robin" strategy in the SD-WAN rule.
• Service-Specific Routing: You can create SD-WAN rules to route specific types of traffic (e.g., VoIP, video conferencing) through a particular ISP based on its performance or reliability. This can be useful if one ISP is better suited for certain applications.
• Monitoring and Alerting: Set up monitoring and alerting to notify you when an ISP outage occurs or when the FortiGate switches between ISPs. This will help you stay informed and take proactive action if needed.
• Regular Testing: Don't just set it and forget it! Regularly test your failover configuration to ensure it's still working correctly. ISPs can change their network configurations, which can affect your failover setup.
• FortiGuard Services: Make sure your FortiGate has the necessary FortiGuard subscriptions (e.g., Web Filtering, Intrusion Prevention) to protect your network from threats, regardless of which ISP is active.
• Firewall Policies: Review your firewall policies to ensure they're compatible with the failover configuration. You may need to adjust the policies to allow traffic to flow correctly through both ISPs.

Troubleshooting Common Issues

Even with the best planning, you might run into some hiccups along the way. Here are a few common issues and how to troubleshoot them:

• Failover Not Working:
  • Check the health check: Make sure the health check is configured correctly and the target IP address is reachable.
  • Verify the static routes: Ensure the static routes for both ISPs are configured correctly and the distances are set appropriately.
  • Review the SD-WAN rule: Double-check the SD-WAN rule to make sure it's configured to use the health check and the correct interfaces.
  • Check the firewall policies: Make sure the firewall policies allow traffic to flow through both ISPs.
• Traffic Not Switching Back to Primary ISP:
  • Check the health check: Ensure the health check for the primary ISP is passing.
  • Verify the interface status: Make sure the primary WAN interface is up and running.
  • Check the logs: Look for any errors or warnings in the FortiGate logs that might indicate why the traffic isn't switching back.
• Intermittent Connectivity Issues:
  • Check the ISP connections: Contact your ISPs to see if they're experiencing any issues.
  • Monitor the interface statistics: Use the FortiGate's interface statistics to monitor for packet loss or errors on the WAN interfaces.
  • Adjust the health check settings: Try adjusting the interval and retry settings on the health check to make it more sensitive to intermittent issues.

By following these tips and troubleshooting steps, you can ensure a smooth and reliable ISP failover configuration on your FortiGate firewall. Remember to always consult the FortiGate documentation and seek help from online resources or Fortinet support if you get stuck.

Conclusion

Configuring ISP failover on your FortiGate firewall is a smart move for any business that relies on a stable internet connection. By following the steps outlined in this guide, you can create a resilient network that can withstand internet outages and keep your business running smoothly. Remember to test your configuration regularly and stay informed about any changes to your network or your ISPs' networks. With a little planning and effort, you can enjoy the peace of mind that comes with knowing your network is protected from the unexpected.

So there you have it, folks! You're now equipped to configure ISP failover on your FortiGate and keep your network humming, no matter what the internet throws your way. Good luck, and happy networking!