Where did IPv5 go?

Question

Since we are all moving towards IPv6 whether we want it or not, I ask this: what happened to IPv5? Was it not cool enough for it's older brother, or did something else happen to that specification?

We... would rather not talk about that-version-which-shall-not-be-mentioned. — Matti Virkkunen, Feb 02 '11 at 21:43
Technically I think IPv6 would be IPv5's *younger* brother. =) — mpontillo, Feb 10 '11 at 06:30
http://en.wikipedia.org/wiki/Leisure_Suit_Larry_4:_The_Missing_Floppies — LeopardSkinPillBoxHat, Jun 06 '12 at 23:48

score 8 · Accepted Answer · answered Feb 02 '11 at 21:45

I believe the answer lies in the "What ever happened to IPv5?" blog post over on http://www.oreillynet.com

To quote:

In the late 1970’s, a protocol named ST — The Internet Stream Protocol — was created for the experimental transmission of voice, video, and distributed simulation. Two decades later, this protocol was revised to become ST2 and started to get implemented into commercial projects by groups like IBM, NeXT, Apple, and Sun. Wow did it differ a lot. ST and ST+ offered connections, instead of its connection-less IPv4 counterpart. It also guaranteed QoS. ST and ST+, were already given that magical “5″.

Ok then. What happened to IPv3? – Brain2000 Nov 12 '13 at 21:19 — Brain2000, Nov 12 '13 at 21:19

score 5 · Answer 2 · answered Feb 02 '11 at 21:44

IPv5 doesn't exist. The Internet Protocol version number 5 was used by a different protocol called ST.

Its second version, known variously as ST-II or ST2, was drafted by Topolcic and others in 1987 and specified in 1990. In RFC 1819, ST2 distinguishes its own packets with an Internet Protocol version number 5, although it was never known as IPv5.

Source

Where did IPv5 go?

2 Answers2