USTAT GRE Tunnels

Enter the interface tunnel command to configure the USTAT end of the GRE tunnel:

Define the tunnel:

interface tunnel 1
 
	ip address 172.25.5.130 255.255.255.252
 
	tunnel destination 10.6.0.1
 
end
 

 

Now assign it to a USTAT:

module ustat provider_1
 
	link provider_1
 
	ip route 10.6.0.1 255.255.255.255 172.16.6.1
 
	ip route 0.0.0.0 0.0.0.0 tunnel1
 
end
 

Designate the tunnel id argument as 1 for the first tunnel, 2 for the second, and 3 for the third. Each tunnel on a system must have a unique ID.

The tunnel destination address is an IP address on the edge router to which the USTAT is connected.

This address can be any valid interface configured on the router. However, for this example, we have followed the common practice of using the router’s loopback address.

Since the loopback address is not in the same logical network as the USTAT module’s interface address, we need to explicitly identify a static route to the loopback address.

Use the ip route command on the USTAT module to create this static route. In this example, we will create host-specific static routes (by using a mask of 255.255.255.255) to the loopback addresses on the edge routers.

Use the ip route command a second time on each USTAT to create a default route through the tunnel to the Internet, using the catch-all address 0.0.0.0 0.0.0.0 and the tunnel interface name tunnel1.

Back out of config-ustat mode using the end (or exit) command, and repeat the three-part process--association of the link, assignment of the VIP and creation of the GRE tunnel--for each USTAT module in your system.