Brian E Carpenter wrote: > > On 2007-12-06 08:39, Iljitsch van Beijnum wrote: > > ULA is LOCAL. > > > > It has nothing to do with PI. > > Another way to say it is that there is a default expectation > that ULAs will be filtered and that PI prefixes will be > routed. That's a good enough rationale for having them in > separate parts of the address space - a ULA being routed > or a PI prefix being filtered are both things that should > raise an operational flag, and that will be easier if they're > distinguishable at a glance. > > There's no sense in looking for any deeper significance > than that.
Actually there is, because the public network operator community -thinks- they know what the important/easy issues are for enterprise network operators. Never mind that they have no real clue about how difficult it is to carve up portions of an otherwise aggregated space and keep that correct at all instances over an extended period of time. Clear separation is a great simplifier, and should be good enough, but repetition of this conversation by people that want nothing more than to tell others how to run their network shows it is not. The place to look for deeper significance is in address selection. The question continually comes up about how a host could possibly select between a restricted local and a global reach prefix if it has both, and the answer is if they are out of the same aggregate they can't. Putting the local use prefix in a part of the space that makes longest-match address selection trivial is the real value behind ULA-C. Tony -------------------------------------------------------------------- IETF IPv6 working group mailing list ipv6@ietf.org Administrative Requests: https://www1.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
