Redundant Load Balancers Using VRRP

Pen offers fault tolerance by automatically rerouting traffic from servers that are offline. But what if the load balancer goes down?

Using VRRP, it is possible to run two load balancers in an active-passive failover configuration. This requires a special vrrp daemon which can be found here. See the instructions that come with vrrpd how to install it.

Example network

Install pen and vrrpd on the two load balancer hosts. Start pen on both load balancers and check that both work by surfing to http://10.1.1.2/ and http://10.1.1.3/.

Now start vrrpd like this on both load balancers:

vrrpd -i eth0 -v 1 10.1.1.4

Now try surfing to http://10.1.1.4/. One of the load balancers will be active and respond at that address. Disconnect that load balancer from the network to simulate a failure. Now the other load balancer will take over the address, restoring functionality.

In the example network, the firewall uses NAT, although that is in no way necessary. A Cisco PIX would be configured something like this:

static (inside,outside) 193.12.6.25 10.1.1.4 netmask 255.255.255.255 0 0
conduit permit tcp host 193.12.6.25 eq 80 any