Cisco 520 Series, Software Configuration Manual

Page: 77 / 162

C H A P T E R
7-1
Cisco Secure Router 520 Series Software Configuration Guide
OL-14210-01
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 7-1 shows a typical deployment scenario.
Figure 7-1 Site-to-Site VPN Using an IPsec Tunnel and GRE
1
Branch office containing multiple LANs and VLANs
2 Fast Ethernet LAN interface—With address 192.168.0.0/16 (also the inside interface for NAT)
3 VPN client—Cisco Secure Router 520 Series routers
4
Fast Ethernet or ATM interface—With address 200.1.1.1 (also the outside interface for NAT)
5
LAN interface—Connects to the Internet; with outside interface address of 210.110.101.1
6 VPN client—Another router, which controls access to the corporate network
7 LAN interface—Connects to the corporate network, with inside interface address of 10.1.1.1
8
Corporate office network
9
IPsec tunnel with GRE
121783
Internet
3
1
2 4 5 7
6
8
9