View source for Cisco Multi-point GRE Routing

[[Category:Cisco Systems]]
When you use tunel mode gre multipoint you have to use numbered ip on the tunnel interface
(you can't use ip unnumbered loopback/fastEthernet etc..).

 interface Tunnel0
  ip address 1.0.0.1 255.255.255.0
  no ip redirects
  ip nhrp map 1.0.0.2 TUNNEL-DESTINATION-ROUTABLE-IP
  ip nhrp map 1.0.0.3 TUNNEL-DESTINATION-ROUTABLE-IP
  ip nhrp map 2.0.0.4 TUNNEL-DESTINATION-ROUTABLE-IP
  ip nhrp network-id 192
  ip nhrp server-only non-caching
  #external ip used for tunnel source
  tunnel source FastEthernet0/1
  tunnel mode gre multipoint
  tunnel key 100
 
If tunnel ip (1.0.0.1) and remote tunnel ip (2.0.0.4) are not in the same subnet you need a route to the remote tunnel ip via tunnel0:
 
 ip route 2.0.0.0 255.0.0.0 tunnel0
You can then have routes to that site via the remote tunnel ip.
 ip route REMOTE-SUBNET MASK 2.0.0.4