On Fri, Jan 13, 2017 at 4:34 PM, Randy Bush <randy(_at_)psg(_dot_)com> wrote:
we have had to fight massively with vendors to make it classless.
please do not give them excuses to break things.
On a lot of hardware /65 - /126 is not very well-supported.
guess the business reason why. the classful spec gave them a good
excuse to do a tcam rinse repeat. i pay to feed the darned chickens,
it's time to break the egg.
But it's true that supporting /65-/126 increases the cost of the device.
The extra bits have to go somewhere. I think I've seen hardware that just
converted all prefixes to 128 bit if there was at least one /65 - /126
prefix in the FIB. That costs money for RAM. Obviously that's silly if
those prefixes are frequent, and you can save that money using better
software engineering - but software engineering costs money too. Prefixes
don't cost money, and if we know that we won't run out of them, what's the
problem?