Austin writes:
George writes:
I am not sure whether the danger in opening up the B space for /17 blocks is particularly bad, but lacking a single consistent policy body with sufficient clue about both the Tier-1 backbone issues and the address allocation issues, it's hard to fault any given ISP for insisting on /16s in B space.
Sounds good, but what exactly does that mean? Does any end network capable of justifying a /24 then get a routable chunk, thus blowing up the tables? What if you could do it based upon traffic generation? That would be difficult to verify, and the definition for 'large' amounts of traffic is ever changing. So, if we say that a /20 is a sufficiently large amount of space to get a routable chunk, then they would be able to get it from ARIN anyway, and we're back to square one. In the far term as space becomes scarce we will need to find a solution to wasted B space, but that is several years out. Perhaps by that time routers will have so much memory and CPU as to make an extra ~4 million possible routes negligible.
The danger of /17 blocks in B space is limited to 64*256 more routes (16 k more, maximum). All at once that would be bad, but over time it would be reasonable. I would personally, were I setting route policy at a Tier 1, allow a /17 in B space, but there's no reason to try and force anyone else to accept that. As others don't right now and aren't inclined to, I would dissuade anyone from trying it as it's either going to be a royal pain or impossible to get routing for. Again, this is where not having a single policy body is killing us; some people get oddball blocks, somehow or another, and are then screwed on routability. I am most certainly not going to suggest radical surgery to the current way of doing it; right now, small places deserving of multihoming have to work at it, and you have to be clued enough to not step in a few holes like trying to portably subdivide a B. I am not sure that there's any obvious fix in the nearterm for those problems, which are avoidable. As long as they're avoidable I think the thing to do is to leave well enough alone. -george william herbert gherbert@crl.com Disclaimer: I speak for myself only, not my ISP, Cats, wife, or car.