H3C Technologies H3C SecPath F1000-E - Manual (Page 45)

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3. On Device A, click Refresh under the tunnel entry list. The P2MP GRE tunnel entry should have
been installed, as shown in Figure 29 .
Figure 29 Verifying the configuration result
Configuration example for P2MP GRE tunnel backup at the
headquarters
Network requirements
As shown in Figure 30 , the headquarters uses two gateways at the egress of the internal network, with
SecPath B for backup. Two GRE tunnels are created on SecPath C, the gateway at the branch, one for
connecting SecPath A and the other for connecting SecPath B. Normally, packets are forwarded along
the tunnel between SecPath A and SecPath C. When a failure occurs along this path, the tunnel between
SecPath B and SecPath C is used to transmit packets.
To meet the above requirements, you need to establish a P2MP GRE tunnel with the branch on both
SecPath A and SecPath B, establish a GRE over IPv4 tunnel between SecPath A and SecPath B, and on
SecPath A, configure the tunnel interface of the GRE over IPv4 tunnel as the backup interface of the P2MP
GRE tunnel interface. Thus, when SecPath A cannot find the corresponding tunnel entry for a packet, it
delivers the packet to SecPath B, which then forwards the packet to SecPath C.
NOTE:
To avoid looping, do not configure the tunnel interface of the GRE over IPv4 tunnel as the backup interface
of the P2MP GRE tunnel interface on SecPath B.