IPv5

• What Happened to IPv5?

IPv5 never became an official protocol.
Internet Stream Protocol (ST) was considered IP version five by industry researchers, but ST was abandoned before ever becoming a standard or widely known as
IPv5
http://stackoverflow.com/questions/4880182/where-did-ipv5-go

• The Internet Stream Protocol (ST and later ST-II) is a family of experimental protocols first defined in Internet Experiment Note IEN-119

Its second version, known variously as ST-II or ST2, was drafted by Claudio Topolcic and others in 1987 and specified in 1990
ST2 distinguishes its own packets with an Internet Protocol version number 5, although it was never known as IPv5
http://en.wikipedia.org/wiki/Internet_Stream_Protocol