Early Review of draft-ietf-pce-state-sync-11
review-ietf-pce-state-sync-11-opsdir-early-ceccarelli-2025-02-03-00

Hello,

please find below my OPS-DIR review.
The draft is well written and easy to read but would benefit from the
explanation of some decisions taken in the design and statements provided
without a justification. I really like the extensive usage of examples, which
clearly explain situations that might be hard to be understood using the text
only.

The synchronization among multiple stateful PCEs and avoidance of computation
loops is for sure a valid use case but i was wondering why the hierarchical PCE
approach is not taken into account (it's also explicitly said in the document).
Wouldn't it be easier to have a hierarchical PCE coordinating the various PCEs
instead of having them talking to each others? I guess the authors have done
this analysis already and providing a comparison between the two approaches in
the draft would be beneficial.

Some more comments related to specific parts of the text below:

- Abstract: For completeness, a stateful PCE can be used also for GMPLS, not
only for MPLS-TE. - Intro: "he hierarchical PCE use case is out of the scope of
this document." see my general comment above. - Intro, figure 1: "when there is
a change in LSP1, the PCC should report to PCE1.  From PCE2's perspective, PCC1
reporting the update of LSP1 to PCE2 is lower than sync it from PCE1 to PCE2."
This statement should be justified. Why the communication PCC1-PCE2 should be
slower than PCE1-PCE2 ? - Section 3.1 only includes 3.1.1 and no extra text,
probably you don't need 3.1.1 and just 3.1 is fine. - Section 3.3: " When
propagating LSP state changes from a PCE to other PCEs, it MUST ensure that a
PCE always uses the freshest state coming from the PCC." i'm not sure i
understand who the subject is, and how it can ensure that the freshest state is
used. - Figure 6: Lenght isn't 16? How long is the LSP state DB version number?
64 bit? do you expect that many version number updates during the lifetime of
an LSP? - Section 3.5: You say taht PCC doesn't need to be aware of teh
computation priority. Then who tells the PCE what is the priority of each
association group? - Section 6: The need of a Path-Vector TLV makes me think
that the hierarchical approach would be simpler. With the hierarchical approach
you wouldn't need a message loop detection mechanisms.

Thanks
Daniele