Subject: [mpls] Eric Rescorla's No Objection on draft-ietf-mpls-rfc3107bis-02: (with COMMENT)

From: Eric Rescorla <[email-masked]>
Date: Wed, 02 Aug 2017 11:16:22 -0700

Eric Rescorla has entered the following ballot position for
draft-ietf-mpls-rfc3107bis-02: No Objection

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COMMENT:
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Document: draft-ietf-mpls-rfc3107bis-02.txt

S 2.1
I note that you use 255 to mean "any number of labels" and 0 is marked
ignore. Is there a reason not to use 255 as a concrete number and 0
to mean "any number"? This is just for my information.

S 2.3.
      Note that failure to set the S bit in the last label will make it
      impossible to parse the NLRI correctly.  See Section 3 paragraph j
      of [RFC7606] for a discussion of error handling when the NLRI
      cannot be parsed.

It would be helpful if you explicitly said that you parse this value
by reading labels one at a time until you get a non-zero S bit. It's
implicity, but having it be clear would be nice.

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From: Eric C Rosen <[email-masked]>
Date: Thu, 3 Aug 2017 09:47:59 -0400

> to mean "any number"? This is just for my information.

There is no real reason.

The NLRI field itself can only be 255 bits long, so there's really only 
room for a handful of labels.  There's no possibility that someone will 
actually need to announce support for 255 labels.