On Tue, Oct 10, 2017 at 7:33 AM, <bruno.decra...@orange.com> wrote: > > From: Job Snijders [mailto:j...@ntt.net] > > Sent: Tuesday, October 10, 2017 2:00 PM > > > > On Tue, Oct 10, 2017 at 11:41:32AM +0000, bruno.decra...@orange.com > wrote: > > > > Any attribute (origin, as_path, aggregator) anywhere can be > overloaded > > > > to mean something only significant to the local network. I think > the > > > > document is simpler without this and see no point in mentioning > this. I > > > > propose: > > > > > > > > OLD: > > > > The LOCAL_PREF value must be lower than the one of the > alternate > > > > path. 0 being the lowest value, it can be used in all cases, > except > > > > if it already has a special meaning within the AS. > > > > NEW: > > > > The LOCAL_PREF value SHOULD be lower than any of the > alternative > > > > paths. It is RECOMMEND to use 0, the lowest LOCAL_PREF value. > > > > > > What is really needed is "The LOCAL_PREF value SHOULD be lower than > > > the one of the alternative path." Looks reasonable to extend it to > > > your proposition " The LOCAL_PREF value SHOULD be lower than any of > > > the alternative paths." So I'm changing for this. > > > > > > Now the value is truly local to an AS, and I'm not sure to see the > > > technical reason to RECOMMEND (SHOULD) a specific value. MAY seems > > > more appropriate to me. Hence I'm proposing to keep "Zero being the > > > lowest value, it MAY be used whichever LOCAL_PREF values are used by > > > the AS." > > > > So the total of the new text is as following? > > > > "The LOCAL_PREF value SHOULD be lower than any of the alternative > > paths. Zero being the lowest value, it MAY be used whichever > > LOCAL_PREF values are used by the AS." > > Yes, that is correct. > > > I am not sure about the second sentence, it seems hard to read. > > I'm open to reformulation. > > > I see value in just recommending a value for people moving between ASNs > > (debugging other organisation's networks via BGP looking glasses) to > > recognise as a highly undesirable path. > > I agree. > > > Reading RFC 2119 the > > 'RECOMMENDED' seems appropiate, "use 0 unless you have a reason not to". > > I'm fine with that part, but the subsequent RFC 2119 text "but the full > implications must be understood and carefully weighed before choosing a > different course." seems too strong for me, as there is just no issue with > an AS choosing a different value. > > > > This is a GROW document and I believe clear-cut guidance will benefit > > all. > > OK. What about using lower case "recommended" ? > Proposed NEW: Zero is the lowest value and MAY be used whichever > LOCAL_PREF values are used by the AS, hence the use of LOCAL_PREF 0 is > recommended. > > (possibly adding "for consistency between ASes and implementations" ) > > Thanks again for your comments. > Kind regards, > --Bruno >
I would prefer a normative RECOMMENDED, the rest of the sentence in RFC2119, just means you should explain the constraints on the alternatives. How about something like this; "The LOCAL_PREF value SHOULD be lower than any of the alternative paths. A LOCAL_PREF value of Zero is RECOMMENDED, however any LOCAL_PREF value lower than all other LOCAL_PREF values used within an AS is an acceptable alternative. The LOCAL_PREF value used, Zero or otherwise, SHOULD NOT also have another use or meaning within the AS." -- =============================================== David Farmer Email:far...@umn.edu Networking & Telecommunication Services Office of Information Technology University of Minnesota 2218 University Ave SE Phone: 612-626-0815 Minneapolis, MN 55414-3029 Cell: 612-812-9952 ===============================================
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