Gre Configuration - Huawei quidway s7700 Configuration Manual

Quidway S7700 Smart Routing Switch
Configuration Guide - VPN
About This Chapter
Generic Routing Encapsulation (GRE) encapsulates the packets of certain network layer
protocols such as Internetwork Packet Exchange (IPX), Asynchronous Transfer Mode (ATM),
IPv6, and AppleTalk so that the encapsulated packets can be transmitted over the IPv4
network. The latest GRE standards specify that GRE can encapsulate Layer 2 frames such as
Point-to-Point Protocol (PPP) frames and Multi-Protocol Label Switching (MPLS) frames.
2.1 Introduction to GRE
The transmission of packets in a GRE tunnel involves two processes: encapsulation and
decapsulation. After receiving a packet of a certain network layer protocol such as IPX that needs
to be encapsulated and routed, the system adds a GRE header to the packet, and then encapsulates
the packet into a packet of another protocol such as IP.
2.2 GRE Features Supported by the S7700
GRE features supported the S7700 include the following: multi-protocol local network
transmission through the single-protocol backbone network, enlargement of the operation scope
of the network running a hop-limited protocol (like IPX), connection of some discontinuous
subnets to establish a VPN, and working in conjunction with IPSec to compensate the flaw of
IPSec in multicast data protection.
2.3 Configuring GRE
You can configure GRE only after a GRE tunnel is configured.
2.4 Configuring a GRE Tunnel Between CE and PE
Configuring a GRE tunnel between a CE and a PE enables the CE to access the public network
through the GRE tunnel.
2.5 Configuring the Keepalive Function
Before configuring a tunnel policy and a GRE tunnel for the VPN, enable the Keepalive function
of the GRE tunnel. In this manner, the VPN does not select the GRE tunnel that cannot reach
the remote end, and data loss can be avoided.
2.6 Maintaining GRE
This section describes how to reset the statistics of a tunnel interface, monitor the running status
of GRE.
2.7 Configuration Examples
Issue 01 (2011-07-15)
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GRE Configuration

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