Implementing Tunneling

Do the following at both ends of the tunnel to implement tunneling:

• Assure that the interfaces for both the tunnel source and destination are reachable using a static route or a routing protocol such as RIP or OSPF and on the S-Series BGP
• Create the interface that will be the source address of the tunnel (usually a loopback interface)
• Create the tunnel interface and enter tunnel configuration mode using the interface tunnel command
• Configure an IP address for the tunnel interface
• Configure the source and destination IPv4 or IPv6 addresses for the L3 tunnel used by the outer header that the packet payload is encapsulated into. This step is not appropriate for a L2 tunnel. Assigning the source and destination addresses for a L2 tunnel will force the tunnel into a down state.
• Configure the encapsulation method (tunnel mode) for the tunnel
• If the configured tunnel mode is GRE:
  • Optionally, configure the keepalive transmit interval and the number of keepalive retries for the tunnel
  • Optionally, configure a GRE keyword used by the receiver to authenticate the source of the packet
• Optionally, configure a GRE L2 tunnel to a Split Horizon group for purposes of loop prevention between tunnels
• Optionally, modify the packet Type of Service
• Optionally, configure a tunnel probe to monitor the destination address associated with the tunnel