Last Call Review of draft-ietf-dnsop-cookies-07
review-ietf-dnsop-cookies-07-opsdir-lc-romascanu-2015-12-22-00

Hi,



I have reviewed draft-ietf-dnsop-cookies-07.txt as part of the Operational
directorate's ongoing effort to review all IETF documents being processed by
the IESG.  These comments were written with the intent of improving the
operational
 aspects of the IETF drafts. Comments that are not addressed in last call may
 be included in AD reviews during the IESG review.  Document editors and WG
 chairs should treat these comments just like any other last call comments.



The I-D describes DNS cookies – a light DNS transaction security mechanism that
provides improved but limited protection to DNS servers and clients against a
number threats described in the document.



I believe the document is 'Almost Ready' for publication. The document is
well-written, the content is clear and seems accurate. Better detailing some of
the operational issues can improve the quality of the document, but none of the
 comments below is a show-stopper.



Below please find my RFC 5706 review.



1.  Has deployment been discussed?  See Section 2.1.



       *  Does the document include a description of how this protocol

          or technology is going to be deployed and managed?



       *  Is the proposed specification deployable?  If not, how could

          it be improved?



       *  Does the solution scale well from the operational and

          management perspective?  Does the proposed approach have any

          scaling issues that could affect usability for large-scale

          operation?



       *  Are there any coexistence issues?



Section 7 is named ‘Deployment;, but in fact it deals with interoperability and
backward compatibility. I do not believe that there are deployment issues with
DNS cookies (scalability, coexistence) but it would be good to explicitly state
this. At the end of this review I am making a proposal concerning the
re-editing of Section 7, including change of name.



   2.  Has installation and initial setup been discussed?  See

       Section 2.2.



       *  Is the solution sufficiently configurable?



       *  Are configuration parameters clearly identified?



       *  Are configuration parameters normalized?



       *  Does each configuration parameter have a reasonable default

          value?



       *  Will configuration be pushed to a device by a configuration

          manager, or pulled by a device from a configuration server?



       *  How will the devices and managers find and authenticate each

          other?



No. Installation and initial setup are not explicitly described. I assume that
the installation is no more complicated than an update of the DNS servers and
clients software. There is no need for synchronization, as interoperability is
ensured at lower security protection levels. It would be good to state these. I
also assume that the configuration parameters and timers described in Section
5.5 are the ones recommended at initial setup. This is not described in the
document either.



   3.  Has the migration path been discussed?  See Section 2.3.



       *  Are there any backward compatibility issues?



This is not a new version of the protocol, but an optional incremental
optimization. Backwards compatibility is described in Section 7.



   4.  Have the Requirements on other protocols and functional

       components been discussed?  See Section 2.4.



       *  What protocol operations are expected to be performed relative

          to the new protocol or technology, and what protocols and data

          models are expected to be in place or recommended to ensure

          for interoperable management?



No such requirements are discussed – there does not seem to be issues.



   5.  Has the impact on network operation been discussed?  See

       Section 2.5.



       *  Will the new protocol significantly increase traffic load on

          existing networks?



       *  Will the proposed management for the new protocol

          significantly increase traffic load on existing networks?



       *  How will the new protocol impact the behavior of other

          protocols in the network?  Will it impact performance (e.g.,

          jitter) of certain types of applications running in the same

          network?



       *  Does the new protocol need supporting services (e.g., DNS or

          Authentication, Authorization, and Accounting - AAA) added to

          an existing network?



The impact on network performance is discussed in section 2 which describes the
benefits of implementing DNS cookies in the context of specific threats. The
impact of using simpler and more complex cookies mechanisms on clients and
servers is not discussed, and it would be good to add such information as well
as the possible trade-offs/



   6.  Have suggestions for verifying correct operation been discussed?

       See Section 2.6.



       *  How can one test end-to-end connectivity and throughput?



       *  Which metrics are of interest?



       *  Will testing have an impact on the protocol or the network?



There is one recommendation about including in implementations counters of
occurrences of events like silence discards. The location of this
recommendation is quite odd (section 1.2 – Terminology)



   7.  Has management interoperability been discussed?  See Section 3.1.



       *  Is a standard protocol needed for interoperable management?



       *  Is a standard information or data model needed to make

          properties comparable across devices from different vendors?



N/A



   8.  Are there fault or threshold conditions that should be reported?

       See Section 3.3.



       *  Does specific management information have time utility?



       *  Should the information be reported by notifications?  Polling?

          Event-driven polling?



       *  Is notification throttling discussed?



       *  Is there support for saving state that could be used for root

          cause analysis?



N/A



   9.  Is configuration discussed?  See Section 3.4.



       *  Are configuration defaults and default modes of operation

          considered?



       *  Is there discussion of what information should be preserved

          across reboots of the device or the management system?  Can

          devices realistically preserve this information through hard

          reboots where physical configuration might change (e.g., cards

          might be swapped while a chassis is powered down)?



Yes –  section 5.5



One more comment. There are a few places where information on operational
issues can be found, and a few more may be missing as per the comments above. I
suggest re-editing section 7 and changing its name from
 ‘Deployment’ to ‘Operational Considerations’. The current text can stay and
 other items be added (like event counters, initial set-up, configuration).
 Again, these edits are not show-stoppers from my perspective but introducing
 them can make the document easier to read and more useful to operators.



I hope this helps.



Regards,



Dan