Corporate Headquarters

tunnel destination 
172.24.2.5 255.255.255.0
Specify the tunnel interface destination address. This 
example uses the IP address and subnet mask of T3 serial 
interface 1/0 of the remote office router.
Step 4
hq-sanjose(config-if)#
tunnel mode gre ip
Configure GRE as the tunnel mode.
GRE is the default tunnel encapsulation mode, so this 
command is considered optional.
Step 5
hq-sanjose(config)# 
interface tunnel 0
hq-sanjose(config-if)# 
no shutdown
%LINK-3-UPDOWN: Interface Tunnel0, changed state 
to up
Bring up the tunnel interface.
1
1.
This command changes the state of the tunnel interface from administratively down to up.
Step 6
hq-sanjose(config-if)#
exit
hq-sanjose(config)# 
ip route 10.1.4.0 
255.255.255.0 tunnel 0
Exit back to global configuration mode and configure 
traffic from the remote office network through the tunnel. 
This example configures traffic from the remote office 
Fast Ethernet network (10.1.4.0 255.255.255.0) through 
GRE tunnel 0.

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3-9
Cisco IOS VPN Configuration Guide
OL-8336-01
Chapter 3 Site-to-Site and Extranet VPN Business Scenarios
Step 1—Configuring the Tunnel
Verifying the Tunnel Interface, Source, and Destination
To verify the configuration:
•
Enter the 
show interfaces tunnel 0
EXEC command to view the tunnel interface status, configured 
IP addresses, and encapsulation type. Both the interface and the interface line protocol should be 
“up.”
ski03_7206#
show interfaces tunnel 1
Tunnel1 is up, line protocol is up 
Hardware is Tunnel
MTU 1514 bytes, BW 9 Kbit, DLY 500000 usec, 
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation TUNNEL, loopback not set
Keepalive not set
Tunnel source 1101:1::1, destination 1501:1::1
Tunnel protocol/transport IPSEC/IPV6
Tunnel TTL 255
Tunnel transmit bandwidth 8000 (kbps)
Tunnel receive bandwidth 8000 (kbps)
Tunnel protection via IPSec (profile "tunpro")
Last input 00:08:23, output 00:04:28, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 3
Queueing strategy: fifo
Output queue: 0/0 (size/max)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
39 packets input, 22734 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
57 packets output, 30130 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 output buffer failures, 0 output buffers swapped out
•
Try pinging the tunnel interface of the remote office router (this example uses the IP address of 
tunnel interface 1 [172.24.3.6]):
hq-sanjose(config)# 
ping 172.24.3.6
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.24.3.6, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/5/8 ms