H3C Technologies H3C SecPath F1000-E - Manual (Page 21)

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This not only ensures better cooperation of devices from different vendors, but also helps avoid
repetitive investments on branch node devices.
• High reliability. It supports GRE tunnel backup at the headquarters and branches, improving the
network reliability.
The P2MP GRE tunnel technology has the following restrictions:
• Both the transport protocol and passenger protocol must be IPv4.
• The headquarters node cannot send packets to a branch before the branch sends packets to it. Only
after receiving a packet from the branch, can the headquarters node install a tunnel entry for the
branch and send packets to the branch.
• No tunnel can be established between branch nodes and therefore branch nodes cannot
communicate with each.
Configuring a P2MP GRE Tunnel
Configuration Prerequisites
On each of the peer devices, configure an IP address for the interface to be used as the source interface
of the tunnel interface (which can be a VLAN interface, GigabitEthernet interface, or loopback interface),
and make sure that this interface can communicate with the interface used as the source interface of the
tunnel interface on the peer device normally.
Configuring a P2MP GRE Tunnel
Follow these steps to configure a P2MP GRE tunnel:
To do… Use the command… Remarks
Enter system view system-view —
Create a tunnel interface
and enter tunnel interface
view
interface tunnel interface-number
Required
By default, a device has no tunnel
interface.
Configure an IPv4 address
for the tunnel interface ip address ip-address { mask |
mask-length }
Required
By default, a tunnel interface has
no IPv4 address.
Set the tunnel mode to P2MP
GRE
tunnel-protocol gre p2mp
Required
By default, the tunnel mode is GRE
over IPv4.
In P2MP GRE tunnel mode, both
the transport protocol and
passenger protocol are IPv4.
Note that you need to configure the
tunnel mode as GRE over IPv4 on
the tunnel peers.