H3C Technologies H3C S12500-X Series Switches - Manual (Page 174)

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• You must configure the tunnel source address and destination address at both ends of a tunnel, and
the tunnel source or destination address at one end must be the tunnel destination or source address
at the other end.
• H3C recommends not configuring the same tunnel source and destination addresses for local
tunnel interfaces that use the same GRE encapsulation protocol.
• If the destination address of a packet before encapsulation is not in the same subnet as the IP
address of the GRE tunnel interface, you must configure a route to the destination address of the
packet over the GRE tunnel interface. You can configure the route by using one of the following
methods:
{
Configure a static route, using the destination address of the original packet as the destination
address of the route and the address of 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, so the dynamic routing protocol can 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.
• You must create a service loopback group, specify its service type as tunnel, and add an unused
Layer 2 Ethernet interface to the service Loopback group. For more information about service
loopback groups, see Layer 2—LAN Switching Configuration Guide.
For information about tunnel interfaces, and the interface tunnel, source, destination, tunnel dfbit enable,
and tunnel discard ipv4-compatible-packet commands, see " Configuring tunneling ."
To configure a GRE over IPv4 tunnel:
Step Command Remarks
1. Enter system view. system-view N/A
2. Create a GRE over IPv4
tunnel interface and
enter its view.
interface tunnel interface-number mode
gre
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 addressing ."
For information about how to assign an
IPv6 address to an interface, see
"
Configuring basic IPv6 settings ."
By 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.