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Operation Manual – GRE
H3C S9500 Series Routing Switches
Chapter 1 GRE Configuration
1-4
II. Scope enlargement of the network running a hop-limited protocol
Figure 1-5
Scope enlargement of the network
When the hop count between two terminals exceeds 15, the terminals cannot
communicate with each other. Using GRE, you can hide some hops so as to enlarge
the scope of the network.
III. VPN creation by connecting discontinuous subnets
Figure 1-6
Connect discontinuous subnets with a tunnel to form a VPN
In the example as shown in
Figure 1-6
, Group1 and Group2 running Novell IPX are
deployed in different cities. They can constitute a trans-WAN virtual private network
(VPN) through the GRE tunnel.
1.2 Configuring a GRE over IPv4 Tunnel
1.2.1 Configuration Prerequisites
Interfaces on a device, such as VLAN interfaces and loopback interfaces, are
configured with IPv4 addresses and can communicate. These interfaces can be used
as the source of a virtual tunnel interface to ensure the reachability of the tunnel
destination address.