Creating the bridge for the GRETAP interface

On each firewall that is part of the GRETAP tunnel, in Configuration > Network > Interfaces:

1. Click on Add, then select Bridge > No members.
   A bridge named new_bridge1 by default is created.
   This name can be changed later.
2. In General configuration > Address range, depending on your network configuration, select Dynamic IP (obtained by DHCP) or Fixed IP to assign to the bridge an IP address in the network that has access to the internet.
3. Click on Apply.
4. Confirm by clicking on Save.