Prerequisites for GRE

The device cannot directly route a tunneled packet based on its destination address. The packet must be sent to a tunnel-type service loopback group, which then delivers the packet to the forwarding module for Layer 3 forwarding. Before you configure GRE, you must configure a tunnel-type service loopback group on the device. For more information about service loopback groups, see Layer 2—LAN Switching Configuration Guide.