Introduction To Gre; Gre Features Supported By The S7700 - Huawei quidway s7700 Configuration Manual

Smart routing switch

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Quidway S7700 Smart Routing Switch

Configuration Guide - VPN

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.

GRE encapsulates the packets of certain network layer protocols such as IP and IPX. After

encapsulation, these packets can be transmitted over the network by another network layer

protocol, such as IP.

GRE can serve as a Layer 3 tunneling protocol for VPNs. A tunnel is a virtual point-to-point

connection and can be regarded as a virtual interface that supports only point-to-point

connections. This interface provides a path to transmit encapsulated datagrams. GRE

encapsulates and decapsulates datagrams at both ends of the tunnel.

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.

Multi-Protocol Local Network Transmission Through Single-Protocol Backbone

Team 1 and Team 2 are the local networks running the IP protocol.

Figure 2-1 Networking diagram of multi-protocol local network transmission through the

single-protocol backbone network

Issue 01 (2011-07-15)

2-1, Group 1 and Group 2 are the local networks running the Novell IPX protocol.

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2 GRE Configuration