Corporate Headquarters

3-3
Cisco IOS VPN Configuration Guide
OL-8336-01
Chapter 3 Site-to-Site and Extranet VPN Business Scenarios
Scenario Descriptions
Figure 3-1
Site-to-Site VPN Business Scenario
Figure 3-2
 shows the physical elements of the scenario. The Internet provides the core interconnecting 
fabric between the headquarters and remote office routers. Both the headquarters and remote office are 
using a Cisco IOS VPN gateway (a Cisco 7200 series with an Integrated Service Adaptor (ISA) or VAM 
(VAM, VAM2, or VAM2+), a Cisco 2600 series router, or a Cisco 3600 series router).
Note
VPN Acceleration Module (VAM) information for your Cisco 7200 series router can be found at 
http://www.cisco.com/en/US/products/hw/routers/ps341/products_installation_and_configuration_guid
es_list.html
.
The GRE tunnel is configured on the first serial interface in chassis slot 1 (serial 1/0) of the headquarters 
and remote office routers. Fast Ethernet interface 0/0 of the headquarters router is connected to a 
corporate server and Fast Ethernet interface 0/1 is connected to a web server. Fast Ethernet interface 0/0 
of the remote office router is connected to a PC client.
Figure 3-2
Site-to-Site VPN Scenario Physical Elements
The configuration steps in the following sections are for the headquarters router, unless noted otherwise. 
Comprehensive configuration examples for both the headquarters and remote office routers are provided 
in the 
“Comprehensive Configuration Examples” section on page 3-39
.
Corporate
Intranet
Headquarters gateway
(hq-sanjose)
Remote office gateway
(ro-rtp)
Remote
office
network
Internet
Serial line
Serial line
GRE tunnel
23244
Fast Ethernet
0/0
10.1.3.3/24
Fast Ethernet
0/0
10.1.4.2/24
Fast Ethernet
0/1
10.1.6.4/24
Headquarters gateway
(hq-sanjose)
Remote office gateway
(ro-rtp)
Internet
Serial 1/0
172.17.2.4/24
Public
Web server
10.1.6.5/24
Private
corporate
server
10.1.3.6/24
Tunnel interface 0
172.17.3.3/24
Tunnel interface 1
172.24.3.6/24
Serial 1/0
172.24.2.5/24
PC A
10.1.4.3/24
GRE tunnel
23245

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