TMS zl Management and Configuration Guide ST.1.0.090213

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Virtual Private Networks

Generic Routing Encapsulation (GRE)

GRE is a Layer 2 protocol that can encapsulate any protocol that Ethernet can

encapsulate. GRE tunneling establishes a virtual point-to-point connection

between two devices across an intervening network. For example, you could

use GRE to tunnel FTP or HTTP traffic between two networks across an

intervening network.

When the TMS zl Module selects traffic for the GRE tunnel, it encapsulates

the traffic with a GRE header and a new IP header. The new IP header includes

the destination address of the remote tunnel endpoint.

Because GRE tunnels do not secure traffic, you should configure GRE over

IPsec for traffic that requires data integrity or data privacy.

The TMS zl Module supports both GRE and GRE over IPsec for tunneling

unicast traffic. It does not support GRE tunneling for multicast traffic.

Create a GRE Tunnel

To create a GRE tunnel, complete the following steps:

1. In the left navigation pane of the Web browser interface, select VPN > GRE.

2. You are at the GRE Tunnels tab.

Figure 7-84. VPN > GRE > GRE Tunnels Window

3. Click Add GRE Tunnel. The Add GRE Tunnel window is displayed.