Thank you for addressing my DISCUSSes and COMMENTs.

This is very well written draft. Nits:

- <striking the request to change DTLS-CID to a 2119 word, as this would create a Normative downref, which is not worth it>
- Please update the DTLS-CID reference; I see that even the current draft is going to expire on 23 April.

Thank you for resolving my Discuss points!

[[ comments ]]

[ section 5 ]

* The first sentence of the 3rd paragraphs reads to me like "while DTLS
  provides protection against replay attacks an attacker can still mount
  a replay attack".

  I don't have any constructive proposal to change this, but if it tickles
  something in your mind that might be more clear to those not super
  knowledgeable about DTLS, I'm sure that'll be great.

Reading the shorter document before the longer one, so I may be missing some important context here.

This was pretty easy to read, so nice work.  A number of editorial comments and suggestions follow:

Section 2:

* "... sent over to both unicast ..." -- s/over to both/over both/, right?

Section 2.1:

* "... intervals, to avoid ..." -- remove the comma

* "Nodes SHOULD drop packets that have been reordered ..." -- Why would an implementer not do this?  (i.e., why is it only a SHOULD?)

Section 2.2:

* "... from the Magic byte ..." -- s/Magic/magic/

Section 2.3:

* Please expand/explain "TLV" on first use.

* Just an aesthetic suggestion: In this sentence...

   Since Babel over DTLS only protects unicast packets, implementors may
   implement Babel over DTLS by modifying an implementation of Babel
   without DTLS support, and replacing any TLV previously sent over
   multicast with a separate TLV sent over unicast for each neighbour.

...you use "implementors", "implement", and "implementation".  Maybe this?

   Since Babel over DTLS only protects unicast packets, implementors may
   provide Babel over DTLS by using a variant of Babel
   without DTLS support, and replacing any TLV previously sent over
   multicast with a separate TLV sent over unicast for each neighbour.

Section 2.5:

* Why is the stuff in the first paragraph only SHOULD/RECOMMENDED?  (The answer may lie in the second paragraph, but I'm uncertain.)

* I suggest that Section 5 should make a backward reference to this section since it talks about mitigation of an attack.

Section 2.6:

* "A node MAY allow configuration options to allow ..." -- change one of those "allow"s to "permit"

Thanks for discussing the port assignment (again)!

Please reply to the rtg-dir review: https://mailarchive.ietf.org/arch/msg/rtg-dir/fuvl_TQmvfqxbtq5Qv12qB_ok4M

Thank you for the work put into this document. I have only two COMMENTs.

Regards,

-éric

== COMMENTS ==

-- Section 1.2 --

The text refers to the security consideration of RFC6121bis for an extended comparison of HMAC & DTLS except that there is no additional information in RFC 6121bis.

-- Section 2.1 --

It is a little unclear to me whether a mix of DTLS and non-DTLS Babel nodes can exist on the same layer-2 network. I guess no (as implied later) but a clear sentence would help.