Last Call Review of draft-ietf-dime-ovli-08
review-ietf-dime-ovli-08-genart-lc-davies-2015-07-27-00

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Document: draft-ietf-dime-ovli-08.txt
Reviewer: Elwyn Davies
Review Date: 2015/07/23
IETF LC End Date: 2015/07/27
IESG Telechat date: (if known) -



Summary: Ready with nits.  A very well written document - thanks.  Some 


minor issues with out-of-date or OBE'd statements that need a bit of 


tweaking.




Major issues:

Minor issues:
s4.2:


Is there a need for and consequently how would one either cancel the 


current abatement algorithm or select a different one?  I guess this 


might happen if the reacting node that was running the algorithm went 


away or itself became overloaded.  However I I have no idea whether this 


is a reasonable question!  OK.. well I see in s5.1.1 that the abatement 


algorithm can be changed... a pointer in s4.2 would be useful.  But 


could it be turned off?






Appendix A.3:  The statements in this appendix are not 'future proof'. 


Referring to ongoing actions of the DIME WG will have little value in 


the future.  Maybe something like "There is an expectation that <these 


developments> will occur and can be integrated with the features 


described in this document."






Appendix C.1, para 1: There are some tense and past/future issues in 


this section - It is now mid 2015 and this para refers in the future to 


'end of 2014'.  Please rewrite to reflect current actualité and in a way 


that will be relevant when this is published as an RFC.




Appendix C.5:



C.5.  No New Vulnerabilities

    The working group believes that DOIC is compliant with the
    requirement to avoid introducing new vulnerabilities.  However, this
    requirement may warrant an early security expert review.


Hmm!  I fear that it would difficult to consider this draft 'ready' if 


there is no reasonable consensus that it hasn't introduced any new 


vulnerabilities.  Has the security expert review actually happened?







REQ 13: The solution MUST NOT introduce substantial additional work
            for a node in an overloaded state.  For example, a
            requirement for an overloaded node to send overload
            information every time it received a new request would
            introduce substantial work.

            *Not Compliant*. DOIC does in fact encourage an overloaded
            node to send an OLR in every response.  The working group
            that other mechanisms to ensure that every relevant node
            receives an OLR would create even more work.  ****[Note: This
            needs discussion.]****


Has this discussion occurred?  Does the WG have consensus that this 


derogation from the requirements is acceptable?




Nits/editorial comments:
General: s/i.e./i.e.,/ g; s/e.g./e.g.,/g


General: Consistent use of "non-supporting" vs "non supporting" (lots of 


places)




s2, Host-Routed Requests:
Expand acronym AVP (first use).

s5.2.1.1:



    A host-type OCS entry is identified by the pair of application-id and
    the node's DiameterIdentity.

    A realm-type OCS entry is identified by the pair of application-id
    and realm.


The application-id, DiameterIdentity and realm presumably come from the 


various messages taht are being piggybacked on.  A reference to the 


relevant section of the RFC that gives definitions of these (and which 


messages to get them from) would be helpful.  Later... this issue is 


partially resolved by s7.3.  A pointer to that section would be 


desirable.  s7.3 needs a reference to where the relevant messages are 


defined.




s5.2.1.4, last para:



    A reporting node MUST keep an OCS entry with a validity duration of
    zero ("0") for a period of time long enough to ensure that any non-
    expired reacting node's OCS entry created as a result of the overload
    condition in the reporting node is deleted.



Is it possible to offer any guidance on what constitutes 'long enough'?

s5.2.2 (in Note):



  Any extension
       that defines a new abatement treatment must also defined the
       interaction of the new abatement treatment with existing
       treatments.



s/defined/define/

s5.3, paras 2, 3, 5,  7  (but probably not the MUST NOT in para 6):


In line with the text in the previous comment, I think s/MUST/must/, 


s/MAY/may/ - they are not things the protocol does




s7:


Pointers are needed to the RFC sections that define the data types and 


the AVP syntax definition structure used in this section.




s7.3 - see comments on s5.2.1.1 above

s8, para 6: s/Diameter identity/DiameterIdentity/ (possibly)



s9.2:  It doesn't seem obvious to me that the values are supposed to 


have names in the registry.  Surely s/b



  (e.g.)
    Feature Vector Entry Name
    Feature Vector Entry Value
    Specification...

s10.3, last para:



    Requirement 28 [RFC7068] indicates that the overload control solution
    cannot assume that all Diameter nodes in a network are trusted, and
    that malicious nodes not be allowed to take advantage of the overload
    control mechanism to get more than their fair share of service.


I can't parse the last phrase of this (from "and that malicious..." 


onwards.  I know what you mean..



Suggest s/trusted, and that/trusted.  It also requires that/

s10.4, last para:



    At the time of this writing, the DIME working group is studying
    requirements for adding end-to-end security features
    [I-D.ietf-dime-e2e-sec-req] to Diameter.


This statement has pretty much been OBE'd.  the draft is in WG last 


call.  I take it we can assume that the draft knows what is being 


specified: thus



These features, when they
    become available, might make it easier to establish trust in non-
    adjacent nodes for overload control purposes.



It should be possible to make a more concrete statement here.



App C.1, para 1: s/normative references/a normative  reference/

App D.1, para 1: s/identity/entity/ (I think)