The objective of this lab exercise is for you to learn how to configure point-to-point GRE tunnels.
Generic Routing Encapsulation (GRE) is IP protocol number 47; its main purpose is to encapsulate any network layer protocol. As a Cisco engineer, as well as in the Cisco CCNA exam, you will be expected to know how to implement GRE tunnels.
This lab is suitable for ICND2 and CCNA certification exam preparation.
This lab has a difficulty rating of 7/10.
When you are ready for your certification exam, you should complete this lab in no more than 20 minutes.
Please use the following topology to complete this lab exercise:
Configure hostnames on R1 and R2 as illustrated in the topology (R1 is on the left).
Configure each router with its respective IPv4 addresses on both of their FastEthernet interfaces.
Configure a GRE tunnel (numbered 1) on each router with the respective IPv4 address (10.10.10.0/30) as per the diagram and add the following settings:
- Tunnel source is interface f0/0;
- Tunnel destination is the other router’s interface f0/0; and
- Set the tunnel mode to GRE.
Configure a static route on R1 to 192.168.2.0/24 via the Tunnel 1 interface, and configure a static route on R2 to 192.168.1.0/24 via the Tunnel 1 interface.
Check the status of the interface tunnel and make sure that traffic is flowing through the tunnel as expected.
Configuration and Verification
For reference information on configuring hostnames, please refer to earlier labs.
For reference information on configuring IP addressing, please refer to earlier labs.
R1#config t Enter configuration commands, one per line. End with CTRL/Z. R1(config)#int Tunnel 1 R1(config-if)#ip address 10.10.10.1 255.255.255.252 R1(config-if)#tunnel source f0/0 R1(config-if)#tunnel destination 172.16.1.2 R1(config-if)#tunnel mode gre ip R2(config)#int Tunnel 1 R2(config-if)#ip address 10.10.10.2 255.255.255.252 R2(config-if)#tunnel source f0/0 R2(config-if)#tunnel destination 172.16.1.1 R2(config-if)#tunnel mode gre ip
R1(config)#ip route 192.168.2.0 255.255.255.0 tunnel 1 R2(config)#ip route 192.168.1.0 255.255.255.0 tunnel 1
R1#sh ip interface brief Interface IP-Address OK? Method Status Protocol FastEthernet0/0 172.16.1.1 YES manual up up FastEthernet0/1 192.168.1.1 YES manual up up Tunnel1 10.10.10.1 YES manual up up R2#sh ip int brief Interface IP-Address OK? Method Status Protocol FastEthernet0/0 172.16.1.2 YES manual up up FastEthernet0/1 192.168.2.1 YES manual up up Tunnel1 10.10.10.2 YES manual up up R1#show interface tunnel 1 Tunnel1 is up, line protocol is up Hardware is Tunnel Internet address is 10.10.10.1/30 MTU 1514 bytes, BW 9 Kbit/sec, DLY 500000 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation TUNNEL, loopback not set Keepalive not set Tunnel source 172.16.1.1 (FastEthernet0/0), destination 172.16.1.2 Tunnel protocol/transport GRE/IP R2#show interface tunnel 1 Tunnel1 is up, line protocol is up Hardware is Tunnel Internet address is 10.10.10.2/30 MTU 1514 bytes, BW 9 Kbit/sec, DLY 500000 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation TUNNEL, loopback not set Keepalive not set Tunnel source 172.16.1.2 (FastEthernet0/0), destination 172.16.1.1 Tunnel protocol/transport GRE/IP