H3C Technologies H3C S12500 Series Switches - Manual (Page 240)

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VPN creation by connecting discontinuous subnets
Figure 98 Connect discontinuous subnets with a tunnel to form a VPN
In the example as shown in Figure 98 , Group 1 and Group 2 running Novell IPX are deployed in different
cities. They can constitute a trans-WAN virtual private network (VPN) through the tunnel.
GRE-IPsec tunnel application
Figure 99 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 guidelines
• The source address and destination address of a tunnel uniquely identify a path. They must be
configured at both ends of the tunnel and the source address at one end must be the destination
address at the other end and vice versa.
• Tunnel interfaces using the same encapsulation protocol must have different source addresses and
destination addresses.