Example: Configuring an IPv4 over IPv4 GRE tunnel

As shown in Figure 98, Group 1 and Group 2 are two private IPv4 networks. The two networks both use private network addresses and belong to the same VPN. Establish a GRE tunnel between Switch A and Switch B to interconnect the two private IPv4 networks Group 1 and Group 2.

	IMPORTANT: By default, interfaces on the devices are disabled (in ADM or Administratively Down state). To have an interface operate, you must use the undo shutdown command to enable that interface.

Before performing the following configuration, configure an IP address for each interface, and make sure Switch A and Switch B can reach each other.

1. Configure Switch A:

   # Create service loopback group 1, and configure the service type as tunnel.

   <SwitchA> system-view
   [SwitchA] service-loopback group 1 type tunnel
   

   # Add port Ten-GigabitEthernet 1/0/3 to service loopback group 1.

   [SwitchA] interface ten-gigabitethernet 1/0/3
   [SwitchA-Ten-GigabitEthernet1/0/3] port service-loopback group 1
   [SwitchA-Ten-GigabitEthernet1/0/3] quit
   

   # Create a tunnel interface Tunnel 1, and specify the tunnel mode as GRE/IPv4.

   [SwitchA] interface tunnel 1 mode gre
   

   # Configure an IP address for the tunnel interface.

   [SwitchA-Tunnel1] ip address 10.1.2.1 255.255.255.0
   

   # Configure the source address of tunnel interface as the IP address of VLAN-interface 101 on Switch A.

   [SwitchA-Tunnel1] source vlan-interface 101
   

   # Configure the destination address of the tunnel interface as the IP address of VLAN-interface 101 on Switch B.

   [SwitchA-Tunnel1] destination 2.2.2.2
   [SwitchA-Tunnel1] quit
   

   # Configure a static route from Switch A through the tunnel interface to Group 2.

   [SwitchA] ip route-static 10.1.3.0 255.255.255.0 tunnel 1
   

2. Configure Switch B:

   # Create service loopback group 1, and configure the service type as tunnel.

   <SwitchB> system-view
   [SwitchB] service-loopback group 1 type tunnel
   

   # Add port Ten-GigabitEthernet 1/0/3 to service loopback group 1.

   [SwitchB] interface ten-gigabitethernet 1/0/3
   [SwitchB-Ten-GigabitEthernet1/0/3] port service-loopback group 1
   [SwitchB-Ten-GigabitEthernet1/0/3] quit
   

   # Create a tunnel interface Tunnel 1, and specify the tunnel mode as GRE/IPv4.

   [SwitchB] interface tunnel 1 mode gre
   

   # Configure an IP address for the tunnel interface.

   [SwitchB-Tunnel1] ip address 10.1.2.2 255.255.255.0
   

   # Configure the source address of tunnel interface as the IP address of VLAN-interface 101 on Switch B.

   [SwitchB-Tunnel1] source vlan-interface 101
   

   # Configure the destination address of the tunnel interface as the IP address of VLAN-interface 101 on Switch A.

   [SwitchB-Tunnel1] destination 1.1.1.1
   [SwitchB-Tunnel1] quit
   

   # Configure a static route from Switch B through the tunnel interface to Group 1.

   [SwitchB] ip route-static 10.1.1.0 255.255.255.0 Tunnel 1
   

# Display tunnel interface information on Switch A.

[SwitchA] display interface tunnel 1
Tunnel1
Current state: UP
Line protocol state: UP
Description: Tunnel1 Interface
Bandwidth: 64kbps 
Maximum transmission unit: 1476
Internet address: 10.1.2.1/24 (primary)
Tunnel source 1.1.1.1, destination 2.2.2.2
Tunnel keepalive disabled
Tunnel TTL 255
Tunnel protocol/transport GRE/IP
    GRE key disabled
    Checksumming of GRE packets disabled
Last clearing of counters: Never
Last 300 seconds input rate: 0 bytes/sec, 0 bits/sec, 0 packets/sec
Last 300 seconds output rate: 0 bytes/sec, 0 bits/sec, 0 packets/sec
Input: 0 packets, 0 bytes, 0 drops
Output: 0 packets, 0 bytes, 0 drops

# Display tunnel interface information on Switch B.

[SwitchB] display interface tunnel 1
Tunnel1
Current state: UP
Line protocol state: UP
Description: Tunnel1 Interface
Bandwidth: 64kbps
Maximum transmission unit: 1476
Internet address: 10.1.2.2/24 (primary)
Tunnel source 2.2.2.2, destination 1.1.1.1
Tunnel keepalive disabled
Tunnel TTL 255
Tunnel protocol/transport GRE/IP
    GRE key disabled
    Checksumming of GRE packets disabled
Last clearing of counters: Never
Last 300 seconds input rate: 0 bytes/sec, 0 bits/sec, 0 packets/sec
Last 300 seconds output rate: 0 bytes/sec, 0 bits/sec, 0 packets/sec
Input: 0 packets, 0 bytes, 0 drops
Output: 0 packets, 0 bytes, 0 drops

# From Switch B, ping the IP address of VLAN-interface 100 on Switch A.

[SwitchB] ping -a 10.1.3.1 10.1.1.1
Ping 10.1.1.1 (10.1.1.1) from 10.1.3.1: 56 data bytes, press CTRL_C to break
56 bytes from 10.1.1.1: icmp_seq=0 ttl=255 time=11.000 ms
56 bytes from 10.1.1.1: icmp_seq=1 ttl=255 time=1.000 ms
56 bytes from 10.1.1.1: icmp_seq=2 ttl=255 time=0.000 ms
56 bytes from 10.1.1.1: icmp_seq=3 ttl=255 time=0.000 ms
56 bytes from 10.1.1.1: icmp_seq=4 ttl=255 time=0.000 ms

--- Ping statistics for 10.1.1.1 ---
5 packet(s) transmitted, 5 packet(s) received, 0.0% packet loss
round-trip min/avg/max/std-dev = 0.000/2.400/11.000/4.317 ms

The output shows that Switch B can successfully ping Switch A.