Re: [Gen-art] Gen-ART Last Call review of draft-ietf-ospf-two-part-metric-05
Brian E Carpenter <brian.e.carpenter@gmail.com> Mon, 08 August 2016 20:18 UTC
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To: "Acee Lindem (acee)" <acee@cisco.com>, "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>
References: <4ee8e895-a939-d747-a82f-fb7c8696b36e@gmail.com> <D3CE3687.7666E%acee@cisco.com>
From: Brian E Carpenter <brian.e.carpenter@gmail.com>
Organization: University of Auckland
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Date: Tue, 09 Aug 2016 08:18:50 +1200
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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 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? >>> 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". >
- Re: [Gen-art] Gen-ART Last Call review of draft-i… Brian E Carpenter
- Re: [Gen-art] Gen-ART Last Call review of draft-i… Acee Lindem (acee)
- Re: [Gen-art] Gen-ART Last Call review of draft-i… Brian E Carpenter
- Re: [Gen-art] Gen-ART Last Call review of draft-i… Jeffrey (Zhaohui) Zhang
- Re: [Gen-art] Gen-ART Last Call review of draft-i… Acee Lindem (acee)
- Re: [Gen-art] Gen-ART Last Call review of draft-i… Brian E Carpenter
- Re: [Gen-art] Gen-ART Last Call review of draft-i… Acee Lindem (acee)
- [Gen-art] Gen-ART Last Call review of draft-ietf-… Brian E Carpenter