Gert Doering wrote: (And because it makes maintenance and setup much easier,
We call that troubleshooting with the seeds of the pants, which exactly what serious operators don't do.
as I don't have to go to some place to find a "get me a free subnet", I just can have the machine assign it ad-hoc, just by telling it the router name/id and the interface name.
This a disaster waiting to happen. A subnet is documented in a subnet database, not in the router's config; the first thing to do *before* configuring a subnet is to create the db record and populate it. Not maintaining proper documentation is cause for termination in lots of shops. Engineering with the seeds of the pants again.
We *have* the address space,
No we *don't*. The IETF standards are decided by consensus, and the IID bits are not yours to play with for routing purposes. There are other legitimate uses for these 64 bits, such as embedding some crypto in the IID or privacy extensions.
Of course it is very much possible with 128 bits. People *do* this, so it's possible, isn't it?
I will laugh when you have to renumber because suddenly a new security protocol that uses 56 of the 64 IID bits is required.
The thing that is not possible is to accommodate for that inside the very narrow-minded "one size fits all" mind-set that made the rule that one should use a /64 on a point-to-point link.
This is called "standardization". That's why you can plug a refrigerator, a microwave oven and a cell phone charger in the same power outlet. The microwave takes 10,000 times more power than the cell phone charger, and indeed the wiring for a power outlet that could accommodate only cell phone chargers would be a lot lighter. Do you want 20 types of power plugs in your data center?
There is no reason (except "one size fits all") *for* that rule - or at least nobody in this discussion named one - but many good reasons *against* it.
This has been debated before and the IETF has decided otherwise. People that maintain correct network documentation do not need nor desire fancy allocation schemes. Often, these same people that maintain correct documentation respect standards, btw. Michel.