Cisco Systems 520 series manual Site-to-Site VPN Using an IPsec Tunnel and GRE

C H A P T E R 7

Configuring VPNs Using an IPsec Tunnel and Generic Routing Encapsulation

The Cisco Secure Router 520 Series routers support the creation of virtual private networks (VPNs).

Cisco routers and other broadband devices provide high-performance connections to the Internet, but many applications also require the security of VPN connections which perform a high level of authentication and which encrypt the data between two particular endpoints.

Two types of VPNs are supported—site-to-site and remote access. Site-to-site VPNs are used to connect branch offices to corporate offices, for example. Remote access VPNs are used by remote clients to log in to a corporate network.

The example in this chapter illustrates the configuration of a site-to-site VPN that uses IPsec and the generic routing encapsulation (GRE) protocol to secure the connection between the branch office and the corporate network. Figure 7-1shows a typical deployment scenario.

Figure 7-1 Site-to-Site VPN Using an IPsec Tunnel and GRE

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Branch office containing multiple LANs and VLANs

Fast Ethernet LAN interface—With address 192.168.0.0/16 (also the inside interface for NAT)

VPN client—Cisco Secure Router 520 Series routers

Fast Ethernet or ATM interface—With address 200.1.1.1 (also the outside interface for NAT)

LAN interface—Connects to the Internet; with outside interface address of 210.110.101.1

VPN client—Another router, which controls access to the corporate network

LAN interface—Connects to the corporate network, with inside interface address of 10.1.1.1

Corporate office network

IPsec tunnel with GRE

Cisco Secure Router 520 Series Software Configuration Guide

OL-14210-01 7-1