Following the motto "simplicity matters , do less get more" I have been following the approach based on open source offering consulting services.
The key points are:
- Load Balancing
The distribution of load request on downstream webservers, coupled with a reliable detection of whether requests can be forwarded to connected servers is one of the main tasks of a load balancer / content switch.
Because the own a very central place in the infrastructure, they should to be redunandant and also partly deal with firewall funtionality.
This can be done with Open Source tools like keepalived, HAProxy, IPVS ( Linux Virtual Server ), pound, pen and varnish. If you
need commercial support, please try http://www.haproxy.com/
- High Availability
The main goal the ressources are everytimes up and running is one of the best explanationof HA.
Widely used here are so-called two-node clusters in active passive mode. If the active fails, the passive one becomes active. Here we have tools such as carp VRRP, ucarp, pacemaker and corosync that will help
With OpenWrt, a narrow, highly customizable Router Firmware VPNs, Gateways, reverse proxies can be created to operate both virtualized and bare metal. Just think of a very powerful Wlan Router, that has no Wlan.