Re: The real reason nobody wants to use it
the committee looking at the successor to IPv4 ruled out variable address lengths as it hurt router performance
Having been there at the time, there wasn't a representative committee as such and nothing was really concluded as a matter of principle. In fact, it was a pretty anarchic process. The Internet Architecture Board were mostly persuaded (partly by Tony Lauck of Digital who had invested a lot of time in the ISO committees) that ISO CLNP was the way to go. The IETF (whose members were largely funded by equipment manufacturers, including Digital, but also Sun, Cisco, etc) revolted at what they saw as a stich-up that would not only advantage one specific manufacturer but shift the standards-making away from the IETF towards ISO.
The real issue with CLNP is it effectively meant that existing router hardware was obsolete - link state routing needs a lot more memory as each router has to store knowledge of the entire network (and we had to make significant changes to the ISO proposals as they went along to make it feasible even to build new routers within the technical and financial constraints of the time) and the longer addresses meant a change in approach to forwarding. Digital was even at this time developing hardware assistance for forwarding that processed incoming packets on a byte-by-byte basis which actually increased performance as you could making a routing decision before you'd even got to the end of the incoming packet header. They had already foreseen that increasing line speeds would mean that routers would inevitably require specialist hardware and that variable-length addresses were only an issue if you were trying to implement routing on what were in effect variants of commodity PCs. That, however, was precisely how Cisco was making its money - cheap 68000-based routers with just enough power to handle the linespeeds of the day. Sun also saw themselves as potential contenders in the same space using their sparc architecture and believed theiy could achieve the best performance taking advantage of its 64-bit word length.
So what really came about was a process in which teams essentially backed by other manufacturers came up with their own competing proposals, most of which were actually very similar but reflected the views of the various engineers about making the most of the hardware they had available at that point.
My view is that, while Digital obviously had a vested interest in promoting a solution on which they had done a great deal of work and for which they had products in development, they were essentially correct. CLNP was perfectly implementable in the next generation of routers that would inevitably be required to deal with increasing line speeds and the current generation of routing hardware (from which Digital was also making significant money) was effectively obsolete anyway as analogue lines were consigned to history. It was also pretty much ready to go, which would have been key to migration. At the time it was still feasible to transition the entire Internet to a new protocol without causing major disruption - it was still mainly confined to research organisations. The delay caused by infighting essentially scuppered that possibility and IPv4 had escaped into commercial networks long before IPv6 was finalised, at which point the commercial operators actively tried to avoid the impact that a transition to IPv6 would have on their business and on their customers and resulted in the foot-dragging that continues today.
Not for the first time, short-term self-interest triumphed over opportunity.
Biting the hand that feeds IT
