Datasheet

Lab – Configuring a Point-to-Point GRE VPN Tunnel
© 2013 Cisco and/or its affiliates. All rights reserved. This document is Cisco Public. Page 7 of 16
With which interfaces are these IP addresses associated? Why?
____________________________________________________________________________________
____________________________________________________________________________________
The tunnel 0 interfaces on both WEST and EAST routers. The traffic is using the tunnel.
f. The ping and traceroute commands should be successful. If not, troubleshoot before continuing to the
next part.
Part 3: Enable Routing over the GRE Tunnel
In Part 3, you will configure OSPF routing so that the LANs on the WEST and EAST routers can communicate
using the GRE tunnel.
After the GRE tunnel is set up, the routing protocol can be implemented. For GRE tunneling, a network
statement will include the IP network of the tunnel, instead of the network associated with the serial interface.
just like you would with other interfaces, such as Serial and Ethernet. Remember that the ISP router is not
participating in this routing process.
Step 1: Configure OSPF routing for area 0 over the tunnel.
a. Configure OSPF process ID 1 using area 0 on the WEST router for the 172.16.1.0/24 and 172.16.12.0/24
networks.
WEST(config)# router ospf 1
WEST(config-router)# network 172.16.1.0 0.0.0.255 area 0
WEST(config-router)# network 172.16.12.0 0.0.0.3 area 0
b. Configure OSPF process ID 1 using area 0 on the EAST router for the 172.16.2.0/24 and 172.16.12.0/24
networks.
EAST(config)# router ospf 1
EAST(config-router)# network 172.16.2.0 0.0.0.255 area 0
EAST(config-router)# network 172.16.12.0 0.0.0.3 area 0
Step 2: Verify OSPF routing.
a. From the WEST router, issue the show ip route command to verify the route to 172.16.2.0/24 LAN on
the EAST router.
WEST# show ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
+ - replicated route, % - next hop override
Gateway of last resort is 10.1.1.2 to network 0.0.0.0
S* 0.0.0.0/0 [1/0] via 10.1.1.2
10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 10.1.1.0/30 is directly connected, Serial0/0/0
L 10.1.1.1/32 is directly connected, Serial0/0/0