Wendy,
On Thu, Oct 24, 2013 at 10:33 AM, Wendy Roome <[email protected]>wrote: > I'm glad to see I can still raise up a controversy! > > It is a very good discussion! > Here's the problem I saw. Consider two network maps: > > MapA: A1 = 10.0.0.0/14 > A2 = 10.0.0.0/15 > > MapB: B1 = 10.0.0.0/16, 10.1.0.0/16, 10.2.0.0/16, 10.3.0.0/16 > B2 = 10.0.0.0/15 > > PIDs A1 and B1 cover exactly the same set of endpoint addresses. So the > naïve view is that those two network maps are dentical. > > But if we strictly apply the "longest prefix match" rule, they are NOT > identical. > In MapA, 10.0.0.0 is in A2, while in MapB, it's in B1. To me, that's > counterintuitive. If y'all like that, fine. I can live with that! But it > should be documented, because I think this has serious potential for > misinterpretation. > Yes. We should document it clearly in the document. The semantics is that: (1) No prefix should belong to two PIDs.; (2) One obtains the union of all prefixes defined by all PIDs; call this set of prefixes P; (3) The longest prefix matching an IP address is identified in P. (4) The PID containing the prefixed identified in (3) is the PID of the IP address. > > And the next bake-off should have a test case for this -- eg, the network > map should define PIDs like B1 and B2, and there should be a test that > 10.0.0.0 is in B1, not B2. > > Good idea to test this in the next bake-off! Richard > - Wendy Roome > > From: "Y. Richard Yang" <[email protected]> > Date: Wed, October 23, 2013 18:47 > To: Sebastian Kiesel <[email protected]> > Cc: IETF ALTO <[email protected]>, Wendy Roome <[email protected]> > > Subject: Re: [alto] Problem with "longest prefix" rule for mapping > endpoints to PIDs > > These are fast responses. It seems that the majority (3:1) is to keep the > non-merging semantics. If we do not hear other objections, we will keep the > current version, but do clarify using the good example from Wendy. > > Cheers, > > Richard >
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