GRE Implementation in Palo Alto Networks Firewalls

• Purpose: GRE tunnels create a point-to-point logical link between two endpoints, allowing for the encapsulation of various network layer protocols. This is useful for directing traffic through specific paths, such as to cloud services or partner networks. :contentReference[oaicite:1]{index=1}
• Configuration Steps:
  1. Create a tunnel interface and assign it to a virtual router and security zone.
  2. Assign an IP address to the tunnel interface.
  3. Configure the GRE tunnel by specifying the local and peer addresses, and associate it with the tunnel interface.
  4. Optionally, enable the Keep Alive function to monitor tunnel health. :contentReference[oaicite:2]{index=2}
  5. Set up routing to direct traffic through the GRE tunnel.
• Considerations:
  • GRE tunnels do not provide encryption; for secure transmission, consider using GRE over IPSec.
  • Quality of Service (QoS) is not supported over GRE tunnels.
  • Ensure that the MTU is adjusted appropriately to account for the additional GRE header to prevent fragmentation. :contentReference[oaicite:3]{index=3}
• Use Cases: GRE tunnels are ideal for scenarios where simple, non-encrypted tunneling is sufficient, such as connecting to cloud-based proxies or steering traffic to partner networks.

For detailed configuration guidance, refer to the official documentation:

• Create a GRE Tunnel
• GRE Tunnel Overview