Re: [Idr] Benjamin Kaduk's No Objection on draft-ietf-idr-bgp-ls-segment-routing-msd-17: (with COMMENT)
Benjamin Kaduk <kaduk@mit.edu> Wed, 06 May 2020 21:33 UTC
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Date: Wed, 06 May 2020 14:33:27 -0700
From: Benjamin Kaduk <kaduk@mit.edu>
To: Alvaro Retana <aretana.ietf@gmail.com>
Cc: Jeff Tantsura <jefftant.ietf@gmail.com>, Susan Hares <shares@ndzh.com>, idr-chairs@ietf.org, draft-ietf-idr-bgp-ls-segment-routing-msd@ietf.org, The IESG <iesg@ietf.org>, idr@ietf.org
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Subject: Re: [Idr] Benjamin Kaduk's No Objection on draft-ietf-idr-bgp-ls-segment-routing-msd-17: (with COMMENT)
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On Wed, May 06, 2020 at 02:22:45PM -0700, Alvaro Retana wrote: > On May 6, 2020 at 1:56:07 PM, Benjamin Kaduk wrote: > > > Ben: > > Hi! > > ... > > It sounds like you are intending this to work the way that I was hoping it > > would work, which is reassuring. That said (and this relates to a later > > comment as well), I think we may want to double-check the wording in one > > spot: in Section 3 we define the "Node MSD is the smallest MSD supported by > > the node on the set of interfaces configured for use." This definition > > seems to disallow advertising a Node MSD that is larger than any specific > > Link MSD for that node. My question here was about whether a receiving > > node was expected to enforce this (surprising) aspect of the definition. > > If, instead, the definition should be changed to say only that the Node MSD > > is the MSD to be used for interfaces on this node in the absence of an > > interface-specific value, then there is no longer any enforcement needed. > > §5 does say this: "When Link MSD is present for a given MSD-type, the > value of the Link MSD MUST take precedence over the Node MSD." > > Is that what you're looking for. That's what I expect, yes. But right now the document seems to be inconsistent, as the Node MSD is claimed to be "the smallest MSD supported" but can be other values. > Keep in mind that the expectation of BGP-LS is to simply transport > information; the rules around that information and how the consumer > should process it come form the IGP documents. IOW, in this case > we're bound by what those published documents already say (see RFC8491 > and RFC8476). So the published documents are also inconsistent? It still looks like we are defining usage of a field that contradicts what that field is defined to carry. I am not sure whether the contradiction is across documents, within multiple documents, or only within this current document. If we're locked into the already-defined semantics that's fine (albeit unfortunate), but we shouldn't then claim that it's allowed to violate the already-defined semantics. -Ben
- [Idr] Benjamin Kaduk's No Objection on draft-ietf… Benjamin Kaduk via Datatracker
- Re: [Idr] Benjamin Kaduk's No Objection on draft-… Jeff Tantsura
- Re: [Idr] Benjamin Kaduk's No Objection on draft-… Ketan Talaulikar (ketant)
- Re: [Idr] Benjamin Kaduk's No Objection on draft-… Acee Lindem (acee)
- Re: [Idr] Benjamin Kaduk's No Objection on draft-… Benjamin Kaduk
- Re: [Idr] Benjamin Kaduk's No Objection on draft-… Alvaro Retana
- Re: [Idr] Benjamin Kaduk's No Objection on draft-… Benjamin Kaduk
- Re: [Idr] Benjamin Kaduk's No Objection on draft-… Jeff Tantsura