On Fri, 24 Aug 2001, Steve Noble wrote:
Now that's confusing.. doesn't CIDR supposedly make it so that one IP is no better or worse then another? Why do people base their filtering policies on where things are in the "Classful" space? How is 64/8 any different then 216/8.. they allocate out of both of them, it's a crapshoot what you get since ARIN denys responsibility to provide routable IP space, yet there is space that is "more" routable than other space.
If we must filter based on minimum allocation boundaries, a new "classful" definition of networks is exactly what we need. Many carriers that have /16's or bigger out of 6x/8 slice and dice it up into multiple /19's and /20's. How is this different from me slicing a /20 up into 16 individual /24's? It's still someone advertising 16 prefixes instead of one, and it causes just as much bloat. but since the prefix lengths are "small enough" to pass through the aggregation police it's for some reason or another considered ok. Unless the RIR's put something out along the lines of: /16's and greater will be allocated out of x/8 /17's will be allocated out of x/8 /18's will be allocated out of x/9 /19's will be assigned out of x/10 /20's will be assigned out of x/10 the filtering methods talked about here will only be half as effective as they should, and some of the worst offenders still get to bloat the tables as much as always. Sure it makes filtering more difficult, but hey if you want to do it, do it right. I know that many questions come up like "what if i get a /20, then another contiguous /20 that can be summarized as a /19" .. that just brings up more questions on how to address the current problems of handing out address space. Paul