Hi Wendy,
On Wed, Oct 23, 2013 at 03:23:50PM -0400, Wendy Roome wrote:
> I just noticed a possible problem with the rule for determining the PID
> for an endpoint address. {5.2.1} says,
>
> "When either an ALTO Client or an ALTO Server needs to determine which
> PID in a Network Map contains a particular IP address, longest-prefix
> matching MUST be used."
>
> Now consider the following network map fragment:
>
> PID1: 1.0.0.0/16 1.1.0.0/16 1.2.0.0/16 1.3.0.0/16
> PID2: 1.0.0.0/15
>
> Obviously PID1's definition is inefficient -- those 4 CIDRs are equivalent
> to 1.0.0.0/14. But unless I missed it, nothing in the protocol spec says
> that's illegal.
>
> So what's the PID for 1.0.0.0? I think we all agree that it should be in
> PID2.
I don't agree. It should be in PID1.
That's how longest prefix matching works.
I am not sure whether your example is relevant in pracice. Maybe you
don't like the beahavior of this algorithm in this example, but at least
it's well-defined and deterministic, and you have the possibility to
define your map in a different way (e.g., completely omit PID1 OR PID2,
whatever you prefer).
So I don't think we should add any additional mechanism, exception, etc.
here.
Just my $0.02
Sebastian
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