Re: [Gen-art] Gen-ART Last Call review of draft-ietf-ospf-two-part-metric-05

"Acee Lindem (acee)" <acee@cisco.com> Wed, 10 August 2016 02:09 UTC

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From: "Acee Lindem (acee)" <acee@cisco.com>
To: Brian E Carpenter <brian.e.carpenter@gmail.com>, "Jeffrey (Zhaohui) Zhang" <zzhang@juniper.net>, "draft-ietf-ospf-two-part-metric.all@ietf.org" <draft-ietf-ospf-two-part-metric.all@ietf.org>, General Area Review Team <gen-art@ietf.org>
Thread-Topic: Gen-ART Last Call review of draft-ietf-ospf-two-part-metric-05
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Date: Wed, 10 Aug 2016 02:09:40 +0000
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Subject: Re: [Gen-art] Gen-ART Last Call review of draft-ietf-ospf-two-part-metric-05
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Hi Brian, 
I believe we got a warning from xml2rfc when we didn’t use the pre-2008
disclaimer (since the draft “updates” RFC 2328).
Thanks,
Acee 

On 8/8/16, 6:32 PM, "Brian E Carpenter" <brian.e.carpenter@gmail.com>
wrote:

>Hi,
>
>That's all good. With the clarifcations, I think the "Updates" is OK too.
>I still don't think you need the pre-2008 disclaimer, but that's a nit.
>
>Thanks
>   Brian
>
>On 09/08/2016 09:27, Jeffrey (Zhaohui) Zhang wrote:
>> Please see -07 version that should address the issues raised by Brian
>>(except that "update" part).
>> 
>> https://tools.ietf.org/html/draft-ietf-ospf-two-part-metric-07
>> 
>> Thanks.
>> Jeffrey
>> 
>>> -----Original Message-----
>>> From: Acee Lindem (acee) [mailto:acee@cisco.com]
>>> Sent: Monday, August 08, 2016 5:02 PM
>>> To: Brian E Carpenter <brian.e.carpenter@gmail.com>;
>>>draft-ietf-ospf-two-
>>> part-metric.all@ietf.org; General Area Review Team <gen-art@ietf.org>
>>> Subject: Re: Gen-ART Last Call review of
>>>draft-ietf-ospf-two-part-metric-
>>> 05
>>>
>>> Hi Brian,
>>>
>>> See one inline.
>>>
>>> On 8/8/16, 4:18 PM, "Brian E Carpenter" <brian.e.carpenter@gmail.com>
>>> wrote:
>>>
>>>> Hi Acee,
>>>>
>>>> Thanks, just a few points in line:
>>>>
>>>> On 09/08/2016 05:47, Acee Lindem (acee) wrote:
>>>>> Hi Brian,
>>>>>
>>>>> Thanks much for the thorough review. Jeffrey and I discussed your
>>>>> comments
>>>>> this morning. See responses to your major/minor comments below. We
>>>>>will
>>>>> incorporate all the nits.
>>>>>
>>>>> On 8/6/16, 9:38 PM, "Brian E Carpenter" <brian.e.carpenter@gmail.com>
>>>>> wrote:
>>>>>
>>>>>> I am the assigned Gen-ART reviewer for this draft. The General Area
>>>>>> Review Team (Gen-ART) reviews all IETF documents being processed
>>>>>> by the IESG for the IETF Chair.  Please treat these comments just
>>>>>> like any other last call comments.
>>>>>>
>>>>>> For more information, please see the FAQ at
>>>>>> <http://wiki.tools.ietf.org/area/gen/trac/wiki/GenArtfaq>.
>>>>>>
>>>>>> Document: draft-ietf-ospf-two-part-metric-05.txt
>>>>>> Reviewer: Brian Carpenter
>>>>>> Review Date: 2016-08-07
>>>>>> IETF LC End Date: 2016-08-15
>>>>>> IESG Telechat date:
>>>>>>
>>>>>> Summary: Almost ready
>>>>>> --------
>>>>>>
>>>>>> Major issues:
>>>>>> -------------
>>>>>>
>>>>>>> Updates: 2328, 5340 (if approved)
>>>>>>
>>>>>> If that is so, the text needs to explain what is changed in those
>>>>>>two
>>>>>> RFCs. Since
>>>>>> this draft describes an "optional extension" to OSPF, it does not
>>>>>> obviously update
>>>>>> them. Is any text in those two RFCs made invalid by this draft?
>>>>>
>>>>> This has been an ongoing debate as to whether an RFC the augments an
>>>>> existing draft updates it or whether it must actually change the
>>>>> existing
>>>>> behavior. In this case, the SPF calculation is modified as specified
>>>>>in
>>>>> section 3.6 but only when the new Network-to-Router metric is
>>>>> advertised.
>>>>> In RFC 2328 and RFC 5340, this cost is always zero (i.e., cost to
>>>>>reach
>>>>> all routers connected to the network is solely the outgoing metric
>>>>> metric
>>>>> or Router-to-Network metric).
>>>>
>>>> OK, fair comment.
>>>>
>>>>>
>>>>> I, for one, would be very happy to have consensus of precisely what
>>>>> constitutes update to an existing RFC.
>>>>
>>>> So would many people, and since it affects all RFC streams, not just
>>>>the
>>>> IETF stream, I happen to know that the RFC Editor is working on
>>>> definitions
>>>> for both "updates" and "obsoletes".
>>>>
>>>>> If we don’t update the existing
>>>>> RFCs, we would avoid the pre-2008 IPR language.
>>>>
>>>> That doesn't seem right. You only need that language if you are
>>>>updating
>>>> whole chunks of older text. If you take a paragraph from a pre-2008
>>>> document,
>>>> change a few words, and patch it into the new document, you need
>>>>either
>>>> the agreement of the original authors or the pre-2008 disclaimer. But
>>>>I
>>>> don't think you're doing that in this case, are you?
>>>
>>> No. We are simply using the context of the existing SPF calculation to
>>> describe the additional function.
>>>
>>> Thanks,
>>> Acee
>>>
>>>
>>>
>>>
>>>>
>>>>>>> 3.6.  SPF Calculation
>>>>>>>
>>>>>>>   During the first stage of shortest-path tree calculation for an
>>>>>>> area,
>>>>>>>   when a vertex V corresponding to a Network-LSA is added to the
>>>>>>>   shortest-path tree and its adjacent vertex W (joined by a link in
>>>>>>> V's
>>>>>>>   corresponding Network LSA), the cost from V to W, which is W's
>>>>>>>   network-to-router cost, is determined as follows:
>>>>>>
>>>>>> I can't parse that sentence. If we delete the subordinate clauses,
>>>>>>we
>>>>>> get
>>>>>>
>>>>>>  When a vertex V is added to the shortest-path tree and its adjacent
>>>>>> vertex W,
>>>>>>  the cost from V to W is determined as follows:
>>>>>>
>>>>>> What does that mean? What does "its" refer to? Is W adjacent to V,
>>>>>>or
>>>>>> is
>>>>>> W adjacent
>>>>>> to the existing tree? Is W added to the tree before V, or is V added
>>>>>> before W?
>>>>>> If I was coding this, I'd have no idea what to do.
>>>>>
>>>>> You really do have to look at RFC 2328 to understand it.
>>>>
>>>> Yes, I did that in some detail when I was teaching routing a few years
>>>> ago ;-)
>>>>
>>>>> Does this
>>>>> modified text parse better?
>>>>>
>>>>>     The first stage of the shortest-path tree calculation is
>>>>>described
>>>>>     in section 16.1 of [RFC 2328] and modified for OSPFv3 as
>>>>>described
>>>>> in
>>>>>     section 4.8.1 of [RFC 5340]. When a vertex V corresponding to a
>>>>> Network-LSA
>>>>>     has just been added to the Shortest Path Tree (SPT) and an
>>>>>adjacent
>>>>> vertex W
>>>>>     (joined by a link in V’s corresponding Network-LSA) is being
>>>>>added
>>>>> to
>>>>>     the SPT, the cost from V to W (W’s network-to-router cost) is
>>>>> determined
>>>>>     as follows:
>>>>
>>>> MUCH better. It also clarifies the "Updates:" aspect.
>>>>
>>>> Thanks
>>>>   Brian
>>>>
>>>>>
>>>>>>
>>>>>>> 3.7.  Backward Compatibility
>>>>>>
>>>>>> This calls for a Router Functional Capability Bit assignment under
>>>>>>RFC
>>>>>> 7770.
>>>>>> The bit number should be given as (say) TBD1 not as 0.
>>>>>>
>>>>>>> 4.  IANA Considerations
>>>>>>
>>>>>> The IANA considerations ask for four assignments. These should be
>>>>>> specified as TBD1,
>>>>>> TBD2, TBD3, TBD4 and the TBDs elsewhere in the text should be
>>>>>>updated
>>>>>> correspondingly.
>>>>>> Also, please reference the relevant RFCs (7770 and whatever defines
>>> the
>>>>>> Sub-TLV registries.)
>>>>>
>>>>> 3.7 and 4 are both fixed in -06 based on comments from Alia.
>>>>>
>>>>>>
>>>>>> Finally, to put this on the standards track, I would really expect
>>>>>>to
>>>>>> see
>>>>>> an Implementation Status section (RFC 7942). Has this been tested?
>>>>>
>>>>> The implementation of this stalled. However, it is viewed by the WG
>>>>>as
>>>>> straight-forward enough to advance.
>>>>>
>>>>>
>>>>>>
>>>>>> Minor issues:
>>>>>> -------------
>>>>>>
>>>>>> Please check the three occurrences of lower-case "must" in Section
>>>>>>3.
>>>>>> Should they be "MUST"?
>>>>>>
>>>>>>> 5.  Security Considerations
>>>>>>>
>>>>>>>   This document does not introduce new security risks.
>>>>>>
>>>>>> That's easy to say but hard to prove. Shouldn't you at least refer
>>>>>>to
>>>>>> the
>>>>>> security
>>>>>> considerations of OSPFv2 and OSPFv3?
>>>>>
>>>>> We will add the reference.
>>>>>
>>>>>>
>>>>>> Also, does section 3.7 introduce a new risk whereby a rogue router
>>>>>> could
>>>>>> flap its
>>>>>> Two-Part Metric bit on and off, causing all its OSPF peers to
>>>>>> continually
>>>>>> recalculate
>>>>>> their routes?
>>>>>
>>>>> This is no more of a risk than other intra-area metric change.
>>>>>
>>>>> Thanks,
>>>>> Jeffrey and Acee
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>
>>>>>> Nits:
>>>>>> -----
>>>>>>
>>>>>>> Requirements Language
>>>>>>
>>>>>> It's unusual to put this at the front. The normal place is after the
>>>>>> Introduction.
>>>>>>
>>>>>>>  This document may contain material from IETF Documents or IETF
>>>>>>>  Contributions published or made publicly available before November
>>>>>>>  10, 2008. ...
>>>>>>
>>>>>> Why is this needed? What did you copy from an old document?
>>>>>>
>>>>>>> 0 OSPF Two-part Metric [TPM]
>>>>>>
>>>>>> The abbreviation TPM is defined but not used, so why bother? Also,
>>>>>> s/[TPM]/(TPM)/ to
>>>>>> avoid confusion with a reference.
>>>>>>
>>>>>>> routes w/o considering any network-to-router costs.
>>>>>>
>>>>>> Just say "without".
>>>>>
>>>>
>> 
>