IP in IP

Alternative forms

 * IP-in-IP

Etymology
Contraction of IP in IP encapsulation used in 2003, which specified the protocol.

Noun

 * 1)  A protocol for sending IP packets over an existing IP network.
 * IP in IP is an unusual mechanism: not only does it use two network layers, it uses the same protocol on both.
 * Although IP in IP incurs an overhead, as the size of the headers is doubled, it may allow you to create a connection between two hosts that would otherwise be blocked by a firewall.