Hi Matt,
Thanks for the review, some (slightly late) comments inline...
-----Original Message-----
From: Matt Miller [mailto:mamille2(_at_)cisco(_dot_)com]
Sent: 28 November 2016 16:58
To: gen-art(_at_)ietf(_dot_)org;
draft-ietf-manet-dlep(_dot_)all(_at_)ietf(_dot_)org
Cc: ietf(_at_)ietf(_dot_)org
Subject: Last Call Review of draft-ietf-manet-dlep-25
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Document: draft-ietf-manet-dlep-25
Reviewer: Matthew A. Miller
Review Date: 2016-11-28
IETF LC End Date: 2016-11-28
IESG Telechat date: 2016-12-15
Summary:
This document is almost ready to publish as a Standards Track document, but
has one major issue that should be resolved, and some minor issues that
may need to be discussed.
Major issues:
* The IANA registries this document establishes are not defined.
One can deduce the required information and its format, but there is no
guidance on review process (for example). I urge the authors to consult RFC
5226 when revisiting the IANA considerations.
We have received similar feedback from the IANA review which we believe we have
addressed in draft-26, which is now published. Could you check to see if we
have addressed your concerns as well?
Minor issues:
* I wonder if any consideration was made to use TLS for at least
confidentiality when exchanging DLEP Messages. I can see where DTLS might
not be practicable -- or even possible -- for the Discovery Signals. However,
the session lifecycle for DLEP Messages makes TLS a better fit.
You are not the only reviewer to raise the thorny issue of TLS. We have
attempted to address this in draft-26.
* In the heartbeats state description (Section 5.3.), it's not clear that
implementations can factor in other received messages in determining when
to send heartbeats. From looking at Appendix
B.7 it's clear that was at least considered, but the text makes no mention. I
think it would be worth expanding on heartbeats to at least hint at this
optimization.
As Stan Ratliff replied to Ben Campbell (who also raised this point):
Our intent was for other messages to "count" as heartbeats - Section 5.3.1
(Heartbeats), says in part: "Receipt of any valid DLEP Message MUST reset the
heartbeat interval timer (i.e., valid DLEP Messages take the place of, and
obviate the need for, additional Heartbeat Messages)."
* In the session termination state description (Section 5.4.), it does not
explicitly allow for an unresponsive peer; it states that an implementation
entering this state "MUST wait for a Session Termination Response Message
(Section 10.10) from its peer", then later hints that an implementation should
enter the Session Reset state when the response is received or it times out.
I suggest that the MUST here explicitly allow for this timeout.
This was raised by at least one other reviewer and has been addressed in
draft-26.
* There seems to be a discrepancy between Section 5.3. "Heartbeats"
and Section 5.4. "Session Termination" with regards to the minimum number
of missed heartbeats before a session should terminate from no response --
2 messages versus 4 messages, respectively. I suggest putting the minimum
limit in either Heartbeats or Session Termination and removing it from the
other.
The intention here was to allow 2 timeouts during normal session flow, but wait
up to 4 timeout-intervals for a Session termination Response message before
aborting the TCP connection.
On the back of other review comments, we may revisit this text an try to
declare some variables that can be referenced to aid clarity in these sections.
Nits/editorial comments:
* In Section 3.1. "Requirements", the mandate to use RFC5082 is said twice --
more generally to all of DLEP in the third paragraph and then specifically to
TCP usage in the fifth paragraph.
This section has been reworked in draft-26, mentioning RFC5082 only once.
* In Section 6. "Transaction Model", the term "destination up" is not
capitalized as it is elsewhere.
Good catch - will fix!
Sorry for the delay in responding, this is the first time I've gone through
this process and I'm not entirely up to speak with etiquette!
Regards,
Rick Taylor
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