Subject: Re: [pcp] MAP with PORT_RESERVATION_OPTION on existing mapping

From: <[email-masked]>
Date: Tue, 24 May 2011 08:17:46 +0200

Hi Simon,

Please see inline.

Cheers,
Med

-----Message d'origine-----
De : [email-masked] [mailto:[email-masked]] De la part de Simon Perreault
Envoyé : mercredi 27 avril 2011 15:34
À : [email-masked]
Cc : [email-masked]
Objet : [pcp] MAP with PORT_RESERVATION_OPTION on existing mapping

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.

Med: You mean two mappings having N/N+1 internal port exit?

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.

Med: The PCP Server can rely on the internal port to detect whether a companion mapping (i.e., for N+1) exists also. The PCP Server has then to refresh these two mappings. No?

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

---

From: Simon Perreault <[email-masked]>
Date: Wed, 25 May 2011 09:25:48 -0400

> Med: The PCP Server can rely on the internal port to detect whether a companion mapping (i.e., for N+1) exists also. The PCP Server has then to refresh these two mappings. No?

Hmmm... Reading my original email I can't remember what the issue was.
Your explanation makes sense to me now. So feel free to consider this
issue as invalid.

Sorry for the noise.

Simon
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