[ih] [ipv6] IP versions explained

Vint Cerf vint at google.com
Sat Nov 7 07:23:43 PST 2009


i did some digging around.

The first documented split of IP from TCP came with TCP v3 which was  
published as IEN21 in January 1978. The "internetwork header" showed a  
variable length (!) source and destination address field among other  
things, separate from the TCP header. This was subsequently revised in  
TCP 3.1 in Feb 1978  with IENs 26, 27, 28 and again, in June 1978 with  
IPv4 and TCPv4 in IENs 40 (TCP) and 41(IP).

IPv5 was an excursion into streaming communication but was abandoned.

v



On Nov 7, 2009, at 9:54 AM, Steve Wilcox wrote:

> Well, "IP" was never of a particular version in the sense that IPv4  
> and IPv6 are compared - they are fundementally different protocols  
> with different ether-types, IP is the first such protocol not the  
> fourth (but the version within the protocol is 4).. (0x0800 which is  
> "IP" currently uses version "4" but IPv6 does not use an 0x0800  
> ethertype with version "6", it actually is a totally different  
> protocol)
>
> I think you are right that the version just recorded the latest  
> version of the IP protocol packet at a time when these things were  
> subject to being changable. Whatever happened to 1, 2, 3 I'm sure  
> you have a better idea that I but what emerged was version=4. I  
> believe later versions were used as proposals for the IPng solution  
> but ultimately it was decided to invent a new addressing scheme and  
> ether protocol entirely and someone decided that calling it "v6" was  
> the way to go.
>
> Searching for this throws up a lot of results which don't seem to be  
> correct.. I think what happened in the 90s and before is not well  
> recorded.. perhaps time to write it up? :-)
>
> I certainly recall when I was getting into networking (during the  
> 90s) that "IP" was nothing special and many variants existed of  
> protocols such as IPX, DEC and within IP we had ether-II, snap, and  
> other things whose names escape me.. all of which seemed quite  
> normal at the time - unlike todays "IP" dominated world!
>
> Steve
>
> On Sat, Nov 7, 2009 at 2:28 PM, Vint Cerf <vint at google.com> wrote:
> This is an incorrect assumption - IPv5 was simply the next version  
> after IPv4. As it happened, it didn't work out very well (scaling  
> problems as I recall) so it was abandoned. IPv6 is, of course, the  
> version with the larger address space. There were no official IPv1  
> or IPv2 versions. I would have to go back to double check whether we  
> split off IP from TCP at TCPv3 or TCPv4. If at v4 then there were  
> never any versions of IP until IPv4. We just numbered in parallel  
> with TCP because of the intimate linkage between the two protocols.
>
> vint
>
>
> On Nov 7, 2009, at 12:47 AM, Michael Shields wrote:
>
>> From http://www.whatismyip.com/ and many other sites:
>>
>> IP version 5: This is an experimental protocol for UNIX based  
>> systems. In keeping with standard UNIX (a computer Operating  
>> System) release conventions, all odd-numbered versions are  
>> considered experimental. It was never intended to be used by the  
>> general public.
>>
>> http://hb.corp.google.com/?mode=sent&sent=IP+version+5:+This+is+an+experimental+protocol+for+UNIX+based+systems.&xsent=IP+version+5:+This+is+an+experimental+protocol+for+UNIX+based+systems.&ref=1
>
>
>
>
> -- 
> Network Operations - Standards & Design
> Google Inc.
> E: stevewilcox at google.com
> M: +44 7920 041930

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