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. But if we apply the "longest-prefix match" on CIDRs, then the
longest CIDR is 1.0.0.0/16 in PID1, which implies that 1.0.0.0 should be
in PID1.
I think the cleanest way to resolve that problem is to say that regardless
of how the PIDs in a CIDR were originally specified, an ALTO server MUST
reduce the CIDRs in a PID to minimum canonical set by combining adjacent
CIDRs. Thus the server's config file might specify PID1 with 4 CIDRs, as
above, but the ALTO server would immediately combine them, and Network Map
Service would say that PID1 is 10.0.0.0/14 and PID2 is 10.0.0.0/15.
But I'm not sure where is the appropriate place to say that. {5.2.1}?
{10.4.4}? {11.2.1}?
- Wendy
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