3Com Switch 8800 Advanced Software V5 Configuration Guide

408 CHAPTER 34: GRE CONFIGURATION
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.
VPN creation by connecting discontinuous subnets
Figure 127 Connect discontinuous subnets with a tunnel to form a VPN
In the example as shown in Figure 127, Group1 and Group2 running Novell IPX
are deployed in different cities. They can constitute a trans-WAN virtual private
network (VPN) through the tunnel.
Configuring a GRE
over IPv4 Tunnel
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.
Configuration Procedure Follow these steps to configure a GRE over IPv4 tunnel:
IP network
Novell IPX protocol
Group 1
Novell IPX protocol
Group 2
GRE tunnel
Router A Router B
To do... Use the command... Remarks
Enter system view system-view -
Enable IPv6 packet forwarding ipv6 Optional
By default, the IPv6 packet
forwarding function is
disabled.
On IPv6 over IPv4 GRE
tunnels, this function is
mandatory.
Create a tunnel interface and
enter tunnel interface view
interface tunnel
interface-number
Required
Not created by default