H3C Technologies H3C SecPath F1000-E - Manual (Page 740)

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VPN establishment by connecting discontinuous subnets
Figure 6 Connect discontinuous subnets with a tunnel to form a VPN
In the example as shown in Figure 6 , subnets Group 1 and Group 2 are deployed in different cities. They
can constitute a trans-WAN virtual private network (VPN) through the tunnel.
GRE-IPsec tunnel application
Figure 7 GRE-IPsec tunnel application
GRE can work with IPsec, allowing data packets like routing protocol, voice, and video packets to be
encapsulated by GRE and then encrypted by IPsec to improve security of data transmission in a tunnel.
Protocols and Standards
• RFC 1701: Generic Routing Encapsulation (GRE)
• RFC 1702: Generic Routing Encapsulation over IPv4 networks
• RFC 2784: Generic Routing Encapsulation (GRE)
Configuring a GRE over IPv4 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, for example, 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.