Subject: [pcp] MAP with PORT_RESERVATION_OPTION on existing mapping

From: Simon Perreault <[email-masked]>
Date: Wed, 27 Apr 2011 09:34:25 -0400

Hi,

How should a PCP server react when it receives a MAP request with a
PORT_RESERVATION_OPTION and it turns out that the mapping already
exists? This can happen with retransmissions, for example.

Trying to refresh both mappings seems to go against text in section 5.
("Two mappings are therefore instantiated by the PCP Server with the
same lifetime value. These mappings are treated as any individual
mapping.") It's possible that the server would have no way to find the
second mapping given the first since they're not linked.

On the other hand, returning an error would go against the PCP design
principle of indempotence.

So I suggest that a MAP request with PORT_RESERVATION_OPTION on an
existing mapping would refresh the first mapping and return success,
just as a normal MAP request would. The second mapping would be
unmodified. It would be refreshed separately, as shown in the examples.

Simon
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