R1 (config) # interface tunnel 0
R1 (config - if) # IP address 10.1.1.1 255.255.255.0
R1 (config - if) # tunnel source 12.1.1.1
R1 (config - if) # tunnel destination 23.1.1.2
Common tunnel for point-to-point network type;
Tunnel interface generation, flow through routing after the search, if forward through the tunnel interface, need to be in the original three npa entered, add a header between public address;
MGRE multi-point network type
Advantages of
1, each site only need to configure a tunnel interface; All the branch site IP address can dynamically change;
2, all the branch node and the center node only build tunnel, but also can directly and other branch site direct communication;
Principle: 1, the center site, fixed the public IP address; Suggested that defined as NHRP server
Site for the center;
2, the tunnel configuration is complete, all the branch site to present information to the NHRP server, local and branch respectively configuration
