NETGEAR ProSafe FVS124G - Manual (Page 223)

Reference Manual for the ProSafe VPN Firewall 25 with 4 Gigabit LAN and Dual WAN Ports
Virtual Private Networking D-9
202-10085-01, March 2005
Figure 9-8: VPN Tunnel SA
The SA contains all the information necessary for gateway A to negotiate a secure and encrypted
communication stream with gateway B. This communication is often referred to as a “tunnel.” The
gateways contain this information so that it does not have to be loaded onto every computer
connected to the gateways.
Each gateway must negotiate its Security Association with another gateway using the parameters
and processes established by IPSec. As illustrated below, the most common method of
accomplishing this process is via the Internet Key Exchange (IKE) protocol which automates some
of the negotiation procedures. Alternatively, you can configure your gateways using manual key
exchange, which involves manually configuring each paramter on both gateways.
Figure 9-9: IPSec SA negotiation
1. The IPSec software on Host A initiates the IPSec process in an attempt to communicate
with Host B. The two computers then begin the Internet Key Exchange (IKE) process.
VPN Gateway A VPN Gateway B
VPN Tunnel
VPN Gateway VPN Gateway
1) Communication
request sent to VPN Gateway
2) IKE Phase I authentication
3) IKE Phase II negotiation
4) Secure data transfer
5) IPSec tunnel termination
IPSec Security Association IKE
VPN Tunnel Negotiation Steps