H3C Technologies H3C S5560 Series Switches - Manual (Page 250)

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Configuring a GRE over IPv4 tunnel
Follow these guidelines when you configure a GRE over IPv4 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.
• H3C recommends not configuring the same tunnel source and destination addresses for local
tunnel interfaces that use the same tunnel mode.
• 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
one of 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.
• 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.