Subject: [Pce] Eric Rescorla's No Objection on draft-ietf-pce-lsp-setup-type-09: (with COMMENT)

From: Eric Rescorla <[email-masked]>
Date: Wed, 04 Apr 2018 08:42:37 -0700

Eric Rescorla has entered the following ballot position for
draft-ietf-pce-lsp-setup-type-09: No Objection

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COMMENT:
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Please expand RP and SRP on first use.

What is the backward compatibility story here? I.e., say I only support method
X and the peer doesn't know about this TLV at all? How will it behave?

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From: Julien Meuric <[email-masked]>
Date: Wed, 4 Apr 2018 18:14:16 +0200

Hi Eric,

As a shepherd, I can address your 2nd concern without waiting for the
authors.

For both defined TLVs, the backward compatibility is addressed by the
last sentence of sections 3 and 4:
"  If a PCEP speaker does not recognize the PATH-SETUP-xxx
   TLV, it MUST ignore the TLV in accordance with ([RFC5440])."

The exact wording will be updated to address other comments, e.g.:
- MUST -> will,
- Make it explicit that an ignored TLV is similar to an absent TLV, and
implies the only existing method before this I-D, i.e. X == RSVP-TE
signaling (cf. Martin's comment).

Thanks,

Julien

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From: Eric Rescorla <[email-masked]>
Date: Wed, 4 Apr 2018 11:27:55 -0700

>    TLV, it MUST ignore the TLV in accordance with ([RFC5440])."

Sorry for not being clear. I meant a different case. What happens when an
existing
PCEP speaker (which is not familiar with this TLV) tries to talk to someone
who
(a) doesn't use RSVP-TE (b) advertises that fact via this mechanism. I
believe
you get some kind of handshake failure. Is that correct?

-Ekr