Last Call Review of draft-ietf-detnet-mpls-05
review-ietf-detnet-mpls-05-tsvart-lc-tuexen-2020-03-15-00

Request Review of draft-ietf-detnet-mpls
Requested rev. no specific revision (document currently at 13)
Type Last Call Review
Team Transport Area Review Team (tsvart)
Deadline 2020-03-13
Requested 2020-02-28
Authors Balazs Varga, János Farkas, Lou Berger, Andy Malis, Stewart Bryant, Jouni Korhonen
Draft last updated 2020-03-15
Completed reviews Rtgdir Last Call review of -04 by Carlos Pignataro (diff)
Opsdir Last Call review of -05 by Shwetha Bhandari (diff)
Tsvart Last Call review of -05 by Michael Tüxen (diff)
Secdir Last Call review of -05 by Watson Ladd (diff)
Secdir Telechat review of -11 by Watson Ladd (diff)
Assignment Reviewer Michael Tüxen 
State Completed
Review review-ietf-detnet-mpls-05-tsvart-lc-tuexen-2020-03-15
Posted at https://mailarchive.ietf.org/arch/msg/tsv-art/FHZtlZARVMb3hMxmQAbDe3EfoNU
Reviewed rev. 05 (document currently at 13)
Review result Ready with Issues
Review completed: 2020-03-15

Review
review-ietf-detnet-mpls-05-tsvart-lc-tuexen-2020-03-15

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.

When done at the time of IETF Last Call, the authors should consider this
review as part of the last-call comments they receive. Please always CC
tsv-art@ietf.org if you reply to or forward this review.

The document is in general pretty generic, so I don't know if the following
was discussed on the mailing list and is described in other documents, but
I think it should be described here or at least pointers to the specification
describing it should be inserted.

The problems I see are related to the Sequence Number you introduce in
Figure 5. If, used it is a 16-bit or 28 bit number. From the example you
provide, it seems that it is used like a Serial Number as described in
RFC 1982. The receiver uses this number for the PEF and POF. If this is
correct, this puts a limitation regarding the number of outstanding
packets on the sender. I don't see this limit being mentioned and I don't
see how this limit is enforced, since there does not seem to be an
acknowledgement.
The document states that an implementation MAY limit the maximum
number of sequence numbers being tracked. What happens if the
receiver runs out of this limit? How does a receiver protect itself against
a sender playing games with the sequence number? Limiting the resources
is only a MAY, so how is this done in the general case?