[OSPF] Spencer Dawkins' No Objection on draft-ietf-ospf-ttz-05: (with COMMENT)

["Spencer Dawkins" <[e-mail]>]

Spencer Dawkins has entered the following ballot position for
draft-ietf-ospf-ttz-05: No Objection

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COMMENT:
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I had some high-level context that took a while to build, but after I got
through the following comments, I found the document clear to read for a
non-OSPF guy. Thank you for that.

The Introduction gives a fairly clear idea of what a TTZ is useful for,
but the Abstract doesn't say anything about that. If we still think that
people read Abstracts separately from RFCs, it would be useful to add a
one-sentence summary naming the use cases that you've already identified
for the Introduction.

Perhaps something like "Topology Transparent Zones" allow network
operators to restructure the areas in their network, and provide services
while the reorganization is taking place, with fewer disruptions." But
you folks would know best.

I'm curious why 

   A TTZ ID is a 32-bit number that is unique for identifying a TTZ.
   The TTZ ID SHOULD NOT be 0. 

is not a MUST. Could you give an example of why that would be a good
idea?

I found 

   A TTZ hides the internal topology of the TTZ from the outside.  It
   does not directly advertise any internal information about the TTZ
to
   a router outside of the TTZ.

very helpful, but it doesn't appear until the top of page 7. Perhaps it
would be useful to put this into the Introduction (and, maybe even the
Abstract). I had been wondering whether that was true from the beginning
of the document, so it seems useful to say so much earlier.