Huawei quidway s7700 - Page 75

The tunnel between Switch A and Switch B adopts the GRE protocol, so that Group 1
communicates with Group 2 without affecting the communication between Team 1 and Team
2.
Enlarging Operation Scope of the Network Running a Hop-Limited Protocol (Like
IPX)
If the hop count between two terminals in Figure 2-2 is more than 15, the two terminals cannot
communicate with each other.
Figure 2-2 Networking diagram of enlarged network operation scope
IP
network
IP
network
IP
network
PC PC
Tunnel
When the tunnel is used in the network, a few hops are hidden. This enlarges the scope of the
network operation.
Connecting Some Discontinuous Sub-Networks to Establish a VPN
GRE tunnels can be used to connect discontinuous sub-networks, as shown in Figure 2-3, Two
sub-networks Group 1 and Group 2 running the Novell IPX protocol are in different cities. A
VPN across the Wide Area Network (WAN) can be established after the tunnel technology is
adopted.
Figure 2-3 Networking diagram of discontinuous sub-networks connected through a tunnel
Group2
Novell
Group1
Novell
IP network
Tunnel
GRE can be applied to both Layer 2 Virtual Private Network (L2VPN) and Layer 3 Virtual
Private Network (L3VPN). Usually, the MPLS VPN backbone network uses label switched
Quidway S7700 Smart Routing Switch
Configuration Guide - VPN 2 GRE Configuration
Issue 01 (2011-07-15) Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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