Telechat Review of draft-ietf-spring-srv6-network-programming-19
review-ietf-spring-srv6-network-programming-19-secdir-telechat-weis-2020-09-22-00

I have reviewed this document as part of the security directorate's ongoing
effort to review all IETF documents being processed by the IESG. These comments
were written primarily for the benefit of the security area directors. Document
editors and WG chairs should treat these comments just like any other last call
comments.

This is a re-review; thanks to the authors for addressing suggestions made in
the first review. The new  security considerations text is good, and logically
correct so I've marked this document as "Ready". But let me explain one way I
think that it could be improved.

The last email exchange was about suggesting that the HMAC TLV be used even
when an SRH is not included in the packet. The newest text "regardless of the 
number of segments in the segment list" implies this case, but there is still a
concern is that implementors won't get this hint about the possible need to
protect just one segment where the SRH is omitted because it's not needed. It
would be nice if this sentence could be more explicit about the need for an
HMAC TLV in this case. For example, something like:
    <old> "regardless of the     number of segments in the segment list." </old>
    <new> "regardless of whether the segments are defined in an SRH header or a
    single segment is passed in the Destination Address." </new>

Thanks.