Re: [Lsr] Benjamin Kaduk's No Objection on draft-ietf-isis-segment-routing-msd-17: (with COMMENT)

Alvaro Retana <> Wed, 26 September 2018 22:41 UTC

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From: Alvaro Retana <>
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Date: Wed, 26 Sep 2018 15:41:23 -0700
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Subject: Re: [Lsr] Benjamin Kaduk's No Objection on draft-ietf-isis-segment-routing-msd-17: (with COMMENT)
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On September 26, 2018 at 5:46:18 PM, Benjamin Kaduk ( wrote:



I don’t see your updated ballot in my archive…hmmm..??

But I wanted to reply to the additional point.  You wrote:

I'm not sure I followed correctly some discussion around the rtgdir
review, specifically the meaning of the indicated MSD value for SR-enabled
vs. non-SR-enabled networks.  In particular, I still don't really understand
why it's okay to use the same codepoint (value 1 as assigned here) for
the max SID depth in SR-enabled networks and for the max label depth
in non-SR MPLS networks.  Why couldn't they just be separate MSD Type

The answer is relatively simple: SR doesn’t change the MPLS architecture,
it just looks at the label stack in a different way by calling the labels a
segment [rfc8402].  IOW, the SID depth is the same as the max label depth
because a segment is the same as a label (for the purposes of forwarding
and considering the max segment/label depth).