US Patent 7941837 Layer two firewall with active-active high availability support

Techniques are described to enable two or more layer two (L2) firewall devices to be configured as a high availability (HA) cluster in an active-active configuration. A first layer two (L2) firewall and a second L2 firewall are positioned within the same L2 network. The first L2 firewall and the second L2 firewall are concurrently configured with active virtual security devices (VSDs) within the L2 network, and concurrently apply L2 firewall services to packets within the L2 network. A VSD of one of the L2 firewalls automatically switches to an active VSD status for a VSD group in place of a VSD of another L2 firewall when the other L2 firewall fails.