paths (LSPs) as the public network tunnel. If the core switch (P) in the backbone network,
however, provides only the IP function without the MPLS function when the PE at the network
edge has the MPLS function, the LSP cannot be used as the public network tunnel. Then, you
can use the GRE tunnel in place of the LSP to provide Layer 3 or Layer 2 VPN solutions at the
core network.
GRE tunnels can also be used as the non-MPLS VPN backbone tunnel. In this case, the private
network packet cannot contain the MPLS label when transmitted in the VPN backbone network.
2.3 Configuring GRE
You can configure GRE only after a GRE tunnel is configured.
2.3.1 Establishing the Configuration Task
Before configuring a GRE tunnel, familiarize yourself with the applicable environment,
complete the pre-configuration tasks, and obtain the data required for the configuration. This
will help you complete the configuration task quickly and accurately.
Applicable Environment
To set up a GRE tunnel, you need to create a tunnel interface first, and then configure GRE
functions on the tunnel interface. If the tunnel interface is deleted, all configurations on the
interface are deleted accordingly.
Pre-configuration Tasks
Before configuring an ordinary GRE tunnel, complete the following tasks:
l
Ensuring the IP connectivity between the source interface and the destination interface
Data Preparation
To configure an ordinary GRE tunnel, you need the following data.
No.
Data
1
Number of the tunnel interface
2
Source address and destination address of the tunnel
3
IP address of the tunnel interface
4
Key of the tunnel interface
2.3.2 Configuring a Tunnel Interface
After creating a tunnel interface, you need to specify GRE as the encapsulation type, set the
source address or source interface of the tunnel, and set the destination address of the tunnel.
You also need to set the network address of the tunnel interface so that the tunnel can support
dynamic routing protocols. The network addresses of both ends of a tunnel must belong to the
same network segment.
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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