Last Call Review of draft-ietf-behave-ipfix-nat-logging-06
review-ietf-behave-ipfix-nat-logging-06-opsdir-lc-romascanu-2016-02-13-00

Hi,



I have reviewed draft-ietf-behave-ipfix-nat-logging-06 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

This document describes the formats for logging of NAT events using IPFIX
Information Elements



I believe the document is 'Almost Ready' for publication. The document is
detailed, the content is clear and seems accurate. Better detailing some of the
operational issues can improve the quality of the document. There is also a need
 for language and grammar improvement, I did not enter on details from this
 respect, but I trust that the RFC Editor will do his job.



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?



There is an Applicability Section which while it really does not seem to be
about Applicability (maybe it should be renamed) provides some information
about deployment. Scalability may be an issue if the collectors are overloaded
by a large number of events simultaneously, this is dealt with a recommendation
for a throttling mechanism.



   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?



The solution is configurable, and there are some indications in Section 9
(Management Considerations). Initial configuration and authentication between
devices and collectors are not discussed, it may be useful to specify that
considerations in IPFIX apply.



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



       *  Are there any backward compatibility issues?



N/A – the logging mechanism is new.



   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?



Support for IPFIX and IEs is discussed.



   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?



Impact on performance and traffic level is discussed and addressed.



   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?



N. Probably not needed.



   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?



Yes. IPFIX and IEs are assumed.



   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?



Yes. Dealt with in detail, as this is about logging based on conditions



   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)?



No. This should be added.



A.2.  Management Considerations



   Do you anticipate any manageability issues with the specification?



   1.  Is management interoperability discussed?  See Section 3.1.



       *  Will it use centralized or distributed management?



       *  Will it require remote and/or local management applications?



       *  Are textual or graphical user interfaces required?



       *  Is textual or binary format for management information

          preferred?



Binary format is used, and the justification is present in the text. Also
mentioned is the need for a management application to translate into human
readable format – but no details are provided. Maybe same considerations as
with IPFIX apply and this should be added.



   2.  Is management information discussed?  See Section 3.2.



       *  What is the minimal set of management (configuration, faults,

          performance monitoring) objects that need to be instrumented

          in order to manage the new protocol?



Yes.



   3.  Is fault management discussed?  See Section 3.3.



       *  Is Liveness Detection and Monitoring discussed?



       *  Does the solution have failure modes that are difficult to

          diagnose or correct?  Are faults and alarms reported and

          logged?



Yes.



   4.  Is configuration management discussed?  See Section 3.4.



       *  Is protocol state information exposed to the user?  How?  Are

          significant state transitions logged?





Yes.



   5.  Is accounting management discussed?  See Section 3.5.



No. Only the Abstract mentions ‘accounting’ and this seems out of context –
maybe the words ‘and for various other purposes of accounting’ should be
deleted. If not I would be curious to know what these words refer to.



   6.  Is performance management discussed?  See Section 3.6.



       *  Does the protocol have an impact on network traffic and

          network devices?  Can performance be measured?



       *  Is protocol performance information exposed to the user?



Performance is not manage, but means to avoid congestion. These seem sufficient.



   7.  Is security management discussed?  See Section 3.7.



       *  Does the specification discuss how to manage aspects of

          security, such as access controls, managing key distribution,

          etc.



There is one reference to privacy which is correct. The Security Considerations
section mainly points to RFC 7011. I will leave to the security review to
assess if this is sufficient.



A few more observations:



1.



A few terms need explanation and a short ‘Terminology and Abbreviations’
section may be useful. For example expand and explain BIB, VRF / VRFIF. Provide
a reference for Carrier Grade NAT (CGN).

2.



In Section 5 there is a reference to a Section 4.1 which does not exist.

3.



The language in the IANA considerations section should be more clear about what
is requested to be added to the IANA IPFIX registry. Expert review from IPFIX
is required, I assume it was / will be performed.



I hope this helps.



Regards,



Dan