What ever happened to IPv5?

by Raffi Krikorian

Because i work on small IP things, I'm constantly asked -- "Will they do IPv6?" "You know, 32-bits aren't enough for light switches... What about IPv6?" "You're not cool until you can do IPv6!" I know, I know. IPv6, whatever. Yes, of course they will do that.

But, what ever happened to IPv5?

IPng, Internet Protocol next generation, was conceived in 1994 with a goal for implementations to start flooding out by 1996 (yeah, like that ever happened). IPv6 was supposed to be the "god-send" over the well-used IPv4: it increased the number of bytes used in addressing from 4 bytes to 16 bytes, it introduced anycast routing, it removed the checksum from the IP layer, and lots of other improvements. One of the fields kept, of course, was the version field -- these 8 bits identify this IP header as being of version "4" when there is a 4 in there, and presumably they would use a "5" to identify this next gen version. Unfortunately, that "5" was already given to something else.

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".

And now as the Internet clock ticks, our PCs don't use IPv5. So we're moving onto 6.


2003-08-05 07:25:39
I just began to learn about IPv6, and kept wondering why there isn't a IPv5 and thought no one has the answer. thanks a lot!
2003-10-01 00:30:32
It was almost IPv7
By the way, at the IETF meeting when IPng was being proposed, it was thought that IPv6 was also assigned and the original version of IPng was going to be 7. After some due diligence, checking the RFCs and talking with Jon Postel, somewhere around the 26th IETF I convinced Phill Gross - then Chairman of the IETF - that we had made a grave mistake in calling IPng version 7 and we corrected the mistake to IPv6.

Geoff Mulligan

2003-11-11 13:10:56
I'm a student in England and none of my course lecturers (in Computing), not even the Networking lecturer that teaches us Networking and Infrastructure, could tell me where IPv5 went. Thanks!

Portsmouth UK

2004-11-27 12:56:54
Not too long ago in my Computer Science course we had a lecture on IP4 vs IP6, the lecturer did say I don't know where IPv5 went, just reading through the notes and remembered that I'd thought I'd check and after saying to myself "What ever happend to IPv5", googled Ipv5 brought up this page.

2006-11-07 17:17:49
Wow, thanks a lot for the explanation. Feel a little more confident now!

Sergey Seleznev
Samsung Electronics

2006-12-12 03:42:22
Acctually, of the internet protocal systems, standards designate that all the odd numbered versions are expirimental. just wait and see id IPv7 never sees the light of day either...

From Wikipedia, the free encyclopedia

IPv5 (Internet Protocol, version 5) was assigned to an experimental protocol called ST (Internet Stream Protocol). ST was first defined in 1979 in IEN 119 (Internet Engineering Note), and was later revised in RFC 1190 (ST2) and RFC 1819 (ST2+). ST was envisioned to be the connection oriented complement to IPv4, but it has never been introduced for public usage. Many of the concepts available in ST can be found today in MPLS.

2007-06-08 21:22:23
I'm a student in USA and none of my course lecturers (in Computing), not even the Networking lecturer that teaches us Networking and Infrastructure, could tell me where IPv5 went. Thanks for telling this good information.
2007-08-22 21:53:59
hi ,dis is jiaa . i'm 4m delhi[INDIA].
First of all many many thanks for telling the hidden truth behind ipv5.....!
mi lecturer has told me this interesting question in the class and finding out the answer .
now i get to know about whole story about ipv4 then protocol st 2 n then ipv6.
Muhammad Rehman
2008-05-10 03:39:18
Well I am not satisfied with the above definition of IPv5. It isint clear enough. It is true that not many books about IPv6 speak about IPv5 (if there was any IPv5 ever). Although I think that IETF jumped 64-bit addresses to 128-bit addresses, because 64-bit addresses could sill be caught up in very near future as of the exponential growth of next generation networks. IPv4=32-bits, IPv5=64-bits, IPv6=128-bits.......and clearly we have skipped IPv5. (This is my own thought and is not an official statement)
2008-05-22 06:34:48
Fantastic bit of work ...!!!
Though a CS student, i too had no idea.