Last Call Review of draft-ietf-6lo-fragment-recovery-11
review-ietf-6lo-fragment-recovery-11-tsvart-lc-perkins-2020-02-10-00

This document has been reviewed as part of the transport area review team's
ongoing effort to review key IETF documents. These comments were written
primarily for the transport area directors, but are copied to the document's
authors and WG to allow them to address any issues raised and also to the IETF
discussion list for information.

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The document updates RFC 4944 to provide a selective fragment recovery
scheme for 6LoWPAN networks. It builds on draft-ietf-6lo-minimal-fragment
and on the virtual reassembly buffers described in the expired draft
draft-ietf-lwig-6lowpan-virtual-reassembly.

The mechanism is generally well described and clearly specified. My main
concern is that the performance of the mechanism will heavily depend on
the values selected for the parameters described in Section 7.1, but
there is little guidance provided on how to set these parameters for
particular link layers. The draft would be improved if it could point
to some more detailed guidance on parameter choice for particualar
scenarios, or to further discussion on how to estimate parameters.

Nits:
Section 1, 3rd paragraph, typo: "[RFC4944] as no selective recovery and the
whole datagram fails when" -> "has no"?

Section 7.1: Description of OptFragmentSize refers to MinFragmentSize