Dear all,
Let's focus on IP prefixes in PID definitions as this has to be
clarified before the protocol document can be finalized.
In other words we are talking about section 5.2.1 of
draft-ietf-alto-protocol-20.txt.
it seems that we could not agree on a tiebreaker algorithm to be
used by the client if it receives a network map defining multiple
PIDs each containing the same IP prefix.
Let me try to summarize with two examples:
MapA: A1 = 10.0.0.0/15
A2 = 10.0.0.0/16, 10.1.0.0/16
is legal, and 10.0.0.1 should be in A2
this is what follows from the current specification, though it may
be surprising to some of us.
MapB: B1 = 10.0.0.0/15
B2 = 10.0.0.0/15, 192.168.0.0/16
is NOT legal.
So my proposal to move forward:
1. clarify that this kind of map as in example B is illegal:
In Sec. 5.2.1:
Old:
Each endpoint MUST map into exactly one PID. Since longest-prefix
matching is used to map an endpoint to a PID, this can be
accomplished by ensuring that no two PIDs contain an identical IP
prefix.
Replace with:
A network map MUST NOT define two or more PIDs that contain
an identical IP prefix, in order to ensure that the longest-prefix
matching algorithm maps each endpoint into exactly one PID.
2. optional: specify client behavior in this error condition
Append a sentence at the end of 5.2.1.
If an ALTO client receives an invalid network map defining two or
more PIDs that contain an identical IP prefix, the ALTO client
SHOULD ignore that prefix and behave as if the prefix did not occur
in any PID definition.
or:
If an ALTO client receives an invalid network map defining two or
more PIDs that contain an identical IP prefix, the ALTO client
SHOULD completely ignore the complete network map.
3. optional: add a clarification that example A above is legal and A2
is the result.
I think that we should add 1) and the first text proposal for 2).
I don't think that we need 3) but I will not object if someone
comes up with a good text proposal.
Comments?
Thanks
Sebastian
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