Private Networking
Private networking is a network that is defined by having a set of servers that can communicate with each
other without having to involve transport over public network. Most private networks involve addressing
servers with virtual IP addresses to ensure public networks can not communicate with them with out the
aid of a firewall or proxy server. In a datacenter environment system administrators will use private
networks to communicate between server to backup systems, exchange real time data, file share, log activity
and securely communicate between servers. The advantageous of having a private network running between
servers is mainly to take advantage of the security and speed at which communication can be done within
servers, in addition in a datacenter environment data transferred within a private network does not get
accounted for by the datacenter and is not billable. Private networks typically work hand in hand with
other services such as load balancing, out of band management and firewalling. In a load balancing situation
system administrators can setup several servers that serve the public side of a network and have each one
of the act as a web-proxy for the real server which may not be publicly accessible, but is accessible on
the private network which provides an added layer of security. The security can then be regulated by a
firewall which then controls communication between the public and private networks. In some cases, when
servers fail or become unresponsive a private network can provide a method to recover unresponsive servers
through internal PXE boot procedures and using lights out cards which are connected to a private network.
In this case a system administrator can program one server on the network to act as a PXE boot server to
distribute a boot image to a server that has failed to boot through its internal media and then with the
usage of either a KVM over IP unit or lights out card can remotely administer the failed server back to
health and restore its online function.
