Heartbeat failover

• Active-Active failover using redundant serial and ethernet hearbeat channels between servers

• Free alternative to HSRP (Hot standby routing protocol) or VRRP (virtual router redundancy protocol) used in commercial firewalls

• Internal and external router addresses are 'floating' IPs that can be shifted between the active firewall

• Also provides failover for chrooted nameservers

  • Primary and secondary nameservers run on one machine in the case of a failure

• Check out http://www.linux-ha.org/