* Gert Doering
On Fri, May 31, 2019 at 09:08:30AM +0200, Tore Anderson wrote:
Also, I am wondering about the thinking behind giving out /24s by default when the minimum assignment size is reduced /27. Why not right-size the assignment all the way down to the minimum assignment size, thus maximising the amount of future entrants the pool can support? There's nothing special about the /24 boundary for the IXP use case, to the best of my knowledge.
We briefly touched this in the WG session last Wednesday. Doing it this way removes the discussion about "larger address block for routing reasons" *if* the IXP in question decides that they do want to announce their prefix.
So, as written today, "if you don't know", you get a /24 which could be routed later. "If you are sure you're small and do not want this announced", you can ask for a /27.../25.
Not advocating anything, just relaying what was the explanation given.
Right. Looking at the DFZ, there is only a single advertisement coming out of the current IXP pool¹: https://stat.ripe.net/widget/routing-status#w.resource=185.1.0.0%2F16 Considering how extremely uncommon this configuration is, I'd prefer it to be the other way around, i.e., that a small IXP with a dozen members would need to explain why they need a /24 in order to get it, otherwise they'd get a /27 by default. If we give out /27s by default to such small IXPs each /24 in the pool can accommodate 8 IXPs. With the current (and proposed) policy we'd need a /21 to accommodate those same 8 IXPs (as I do not imagine any of them explicitly requesting something smaller than what's on offer by default). This seems wasteful. [1] I was told on IRC that the reason for the specific advertisement seen is to provide some kind of quasi-OOB Internet transit service to the IXP members. If that is correct it seems to me to possibly run afoul of the first bullet in section 6.1, but whatever. Tore