H3C Technologies H3C SecPath F1000-E - Manual (Page 9)

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• For information about commands interface tunnel, tunnel-protocol, source, destination,
and encapsulation-limit, see Tunneling Commands in the IP Services Volume.
• For more information about tunnel interfaces and related configurations, see Tunneling
Configuration in the IP Services Volume.
• If you delete a tunnel interface, the functions configured on this tunnel interface will be removed as
well.
• The source address and destination address of a tunnel uniquely identify a path. They must be
configured at both ends of the tunnel and the source address at one end must be the destination
address at the other end and vice versa.
• Tunnel interfaces using the same encapsulation protocol must have different source addresses and
destination addresses.
• If you configure a source interface for a tunnel interface, the tunnel interface takes the primary IP
address of the source interface as its source address.
• You can enable or disable the checksum function at both ends of the tunnel as needed. If the
checksum function is enabled at the local end but not at the remote end, the local end calculates the
checksum of a packet to be sent but does not check the checksum of a received packet. Contrarily,
if the checksum function is enabled at the remote end but not at the local end, the local end checks
the checksum of a received packet but does not calculate the checksum of a packet to be sent.
• When configuring a route through the tunnel, you can configure a static route, using the address of
the network segment the original packet is destined for as its destination address and the address
of the peer tunnel interface as its next hop. Or, you can enable a dynamic routing protocol on both
the tunnel interface and the device interface connecting the private network, so that the dynamic
routing protocol can establish a routing entry that allows the tunnel to forward packets through the
tunnel. It is not allowed to set up a static route whose destination address is in the subnet of the
tunnel interface.
Displaying and Maintaining GRE
To do… Use the command… Remarks
Display information about a
specified or all tunnel interfaces display interface tunnel
[ number ]
Available in any view
Display IPv6 information about a
tunnel interface display ipv6 interface tunnel
[ number ] [ verbose ]
Available in any view
NOTE:
For information about commands display interface tunnel and display ipv6 interface tunnel, see Tunneling
Commands in the IP Services Volume.
GRE over IPv4 Tunnel Configuration Example
Network requirements
Device A and Device B are interconnected through the Internet. Two private IPv4 subnets Group 1 and
Group 2 are interconnected through a GRE tunnel between the two devices.