User's Manual Part 2

Appendix C - VPNs
107
Because the IKE and IPsec connections are separate, they have different SAs (security associa-
tions).
Policies
VPN configuration settings are stored in Policies.
Note that different vendors use different terms. Generally, the terms "VPN Policy", "IPSec
Policy", and "IPSec Proposal" have the same meaning. However, some vendors separate IKE
Policies (Phase 1 parameters) from IPSec Policies (Phase 2 parameters).
For the Wireless ADSL Router; each VPN policy contains both Phase 1 and Phase 2 parameters
(if IKE is used). Each policy defines:
• The address of the remote VPN endpoint
• The traffic which is allowed to use the VPN connection.
• The parameters (settings) for the IPsec SA (Security Association)
• If IKE is used, the parameters (settings) for the IKE SA (Security Association)
Generally, you will need at least one (1) VPN Policy for each remote site for which you wish to
establish VPN connections.
It is possible, and sometimes necessary, to have multiple Policies for the same remote site.
However, you should only Enable one (1) policy at a time.
VPN Configuration
The general rule is that each endpoint must have matching Policies, as follows:
VPN Endpoint
address
Each VPN endpoint must be configured to initiate or accept connec-
tions to the remote VPN client or Gateway.
Usually, this requires having a fixed Internet IP address. However, it is
possible for a VPN Gateway to accept incoming connections from a
remote client where the client's IP address is not known in advance.
Local & Remote
LAN definition
This determines which outgoing traffic will cause a VPN connection to
be established, and which incoming traffic will be accepted. Each
endpoint must be configured to pass and accept the desired traffic from
the remote endpoint.
If connecting 2 LANs, this requires that:
• Each endpoint must be aware of the IP addresses used on the
other endpoint.
• The 2 LANs MUST use different IP address ranges.
IKE parameters If using IKE (recommended), the IKE parameters must match (except for
the SA lifetime, which can be different).
IPsec parameters The IPsec parameters at each endpoint must match.