A firewall fault-tolerant network interface system includes a switch
circuit configured to detect when a firewall fails in a multi-firewall
local network. When a failed firewall is detected, the switch circuit
waits for a time-out period to expire to allow convergence. The switch
circuit then intervenes when traffic from a server to the failed firewall
is detected. The switch circuit translates the MAC address of the failed
firewall to the MAC address of a functional firewall. Traffic from a
server originally directed to the failed firewall is then redirected to a
functional firewall. In a further refinement, the switch circuit provides
the MAC address of a functional firewall in response to an ARP request
from a server to the failed firewall. Thus, traffic from this server will
be directed to the functional firewall without further intervention,
reducing the overhead of the switch circuit. In still a further
refinement, if the failed firewall recovers, the switch circuit waits for
a time-out period to expire to allow convergence of external firewalls
and to allow the recovered firewall to learn routes to known clients. The
switch circuit then ceases all intervention for the MAC address of the
now-recovered firewall.