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Configuration guidelines 
Follow these guidelines when you configure a GRE/IPv6 tunnel: 
•  You must configure the tunnel source address and destination address at both ends of a tunnel. 
The tunnel source or destination address at one end must be the tunnel destination or source 
address at the other end. 
•  As a best practice, do not configure the same tunnel source and destination addresses for local 
tunnel interfaces that use the same tunnel mode. 
•  You can enable or disable GRE checksum at each end of a tunnel. If GRE checksum is enabled 
at a tunnel end, the tunnel end sends packets carrying the checksum to the peer end. A tunnel 
end checks the GRE checksum of a received packet if the packet carries a GRE checksum, 
whether or not the tunnel end is enabled with GRE checksum. 
•  To ensure correct packet forwarding, identify whether the destination network of packets and 
the IP address of the local tunnel interface are on the same subnet. If they are not, configure a 
route reaching the destination network through the tunnel interface. You can configure the route 
by using the following methods: 
{  Configure a static route, using the local tunnel interface as the outgoing interface of the 
route. 
{  Enable a dynamic routing protocol on both the tunnel interface and the interface connecting 
the private network. This allows the dynamic routing protocol to establish a routing entry 
with the tunnel interface as the outgoing interface. 
•  The IP address of the tunnel interface and the tunnel destination address configured on the 
tunnel interface must be in different subnets. 
For information about tunnel interfaces, the interface tunnel, source, destination, and tunnel 
discard ipv4-compatible-packet commands, and additional configuration commands on a tunnel 
interface, see "Configuring tunneling." 
Configuration procedure 
To configure a GRE/IPv6 tunnel: 
 
Step Command Remarks 
1.  Enter system view. 
system-view
 N/A 
2.  Create a GRE tunnel 
interface, and specify the 
tunnel mode as GRE/IPv6. 
interface tunnel
 
interface-number 
mode
 
gre ipv6
 
By default, the device has no tunnel 
interface. 
You must configure the same tunnel mode 
on both ends of a tunnel. Otherwise, 
packet delivery might fail. 
3.  Configure an IPv4 or IPv6 
address for the tunnel 
interface. 
For information about 
how to assign an IPv4 
address to an interface, 
see "Configuring IP 
addr
essing." 
For information about 
how to assign an IPv6 
address to an interface, 
see "Configuring basic 
IPv6 settings." 
B
y default, no IPv4 or IPv6 address is 
configured for a tunnel interface. 
When the passenger protocol is IPv4, 
configure an IPv4 address for the tunnel 
interface. When the passenger protocol is 
IPv6, configure an IPv6 address for the 
tunnel interface.