Internet Protocol version 5
After IPv4 and before IPv6 there should have been IPv5. Indeed, there was. In 1979, the Internet Stream Protocol (ST) was defined as an extension to IPv4 that supported multimedia applications. It defined such things as traffic flows, connection oriented services, and Quality of Service (QoS). It was before its time and was never implemented on the Internet or in vendor equipment. Many of the concepts of IPv5, however, were incorporated into MPLS.
|<mp3>http://podcast.hill-vt.com/podsnacks/2007q3/ipvx.mp3%7Cdownload</mp3> | IP version 5 (IPv5)|