Nortel Contivity 1050, Configuration Manual

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Nortel VPN Router Configuration — Basic Features
Chapter 6
Configuring branch office tunnels
The branch office feature allows you to configure a secure tunnel connection
between two private networks. Typically, one private network is behind a locally
configured Nortel VPN Router while the other is behind a remote Nortel VPN
Router. Branch office configuration allows you to configure the accessible
subnetworks behind each Nortel VPN Router. The configuration also contains the
information that is necessary to set up the connection, such as the Nortel VPN
Router’s IP addresses, encryption types, and authentication methods. You can
apply local policy restrictions, such as access hours, filter sets, and call admission
priorities, to limit connectivity into local subnetworks.
The Nortel VPN Router supports symmetric, or peer-to-peer branch office tunnels
with fixed endpoints, and asymmetric branch office tunnels. An asymmetric
branch office tunnel is a branch office tunnel where one of the endpoints does not
have a fixed IP address. Such situations exist in the small branch office or SOHO
environments where the Nortel VPN Router’s public interface is behind a DSL or
cable modem. The DSL or cable modem services typically do not guarantee a
static IP address. Branch office tunnels in these situations are asymmetric because
only one side of the tunnel can initiate a connection.
Figure 19 on page 120 shows a typical branch office environment.