Hi Tony, Please check inline below.
On Wed, Jun 22, 2022 at 9:41 PM Tony Przygienda <tonysi...@gmail.com> wrote: > hey Ketan, since as you know ;-) BGP-LS is not really IGP 1:1 translation > we try to put into BGP-LS here only the stuff that is strictly needed for > topology discovery and understanding for advanced computation and nothing > else. > KT> I don't agree with the "nothing else". At least I can't claim to have the full knowledge of all the solutions being designed and deployed using BGP-LS. > And hence, since the 1:1 TLV correspondence is nowhere to be seen by now > if you look at ospf/isis encoding and what BGP-LS formats are today your > requirements are interesting but I'm not sure where they came from. > KT> Not everything from OSPF/ISIS is in BGP-LS, but whatever we've put follows closely the semantics and encoding (with due consideration for normalization across the IGPs). So I don't support the design of BGP-LS encodings that are different from the underlying IGPs without strong justification. > > > The flag indicates already whether something is client or reflector on an > adjacency. cluster ID is there as well to differentiate between different > clusters. L2 C/FR adjacencies will show up as well. good enough to > understand topology and compute AFAIS. All this is achievable by putting > this element on the link TLV (the draft should explain it better, it just > grabs codepoints in node/link/prefix & e'thing else ;-). Yes, we could > annotate just the node assuming strict adherence to the IGP draft today but > putting the element on the link descriptor follows the IGP spec itself and > will allow to break the RFC if necessary later also in BGP-LS (by e.g. > allowing a node to be client of two different clusters or even a node being > reflector for 2 different clusters. Observe that this will not work in case > of auto-discoery since that's on node caps ;-) But those are sutble > discussions that need to be documented into the BGP-LS draft as procedures > once adopted. > KT> So you see the scope for adding some more of the sub-TLVs from the ISIS flood-reflection draft into this BGP-LS document? If so, great - we can always extend on a need basis. > Those discussions are natural and necessary since BGP-LS is NOT IGP > database but a distorted, simplified view for topology discovery. Or at > least that's how it's used in reality based on the shortcomings of its > design ;-) > > As I explained, unless L1 adjacencies are being formed IMO they don't > belong into BGP-LS FR information, otherwise will show up in BGP-LS > naturally. Neither does IMO auto-discovery of FR. > > As to mismatch of e.g. cluster ID/role. good observation but we don't send > IIHs in BGP-LS either to discover MTU mismatch so I don't see that's what > BGP-LS is here for > KT> The main sticking point for me here is that you have not allowed for the BGP-LS Flood Reflection TLV to have support for sub-TLVs as is the case with its underlying ISIS Flood Reflection TLV. It is a very minor thing that can be easily fixed and I am unable to understand why this cannot or should not be done. Anyway, I rest my case :-) Thanks, Ketan > > -- tony > > On Wed, Jun 22, 2022 at 4:44 PM Ketan Talaulikar <ketant.i...@gmail.com> > wrote: > >> Hi Tony, >> >> I may not be the best judge, for this feature, of which of the ISIS >> sub-TLV need to get into BGP-LS and which do not. In my limited >> understanding of the feature and its deployment, the other 3 sub-TLVs would >> be equally useful to get into BGP-LS. Isn't the Flood Reflection >> Adjacency Sub-TLV the one that distinguishes a "normal" ISIS adjacency >> from a reflector adjacency formed over the tunnel? Isn't it useful to know >> what sort of tunnel encapsulation is being signaled so a discrepancy >> between the two ends can be detected? >> >> I am copying LSR WG which probably is the better group than IDR to review >> and comment on this. >> >> In any case, I am ok to go ahead and skip the inclusion of certain ISIS >> sub-TLVs in BGP-LS - they can be always added later on. >> >> But I am not ok that while the ISIS Flood Reflection TLV has support for >> sub-TLVs, its corresponding BGP-LS ISIS Flood Reflection TLV does not allow >> for sub-TLVs. The encoding needs to be consistent. That is a show-stopper >> in my opinion. >> >> Thanks, >> Ketan >> >> >> On Wed, Jun 22, 2022 at 7:29 PM Tony Przygienda <tonysi...@gmail.com> >> wrote: >> >>> Ketan, AFAIS tunnel status is not part of IGP state and should be >>> derived from alternate mechanisms just like interface up/down state on the >>> node. We don't carry interface up/down in BGP-LS today and should not >>> (observe that I really mean admin/phy up/down and not IGP adj up/down >>> here). And then, those L1 tunnels either form IGP adjacencies on them in >>> which case you'll get them in BGP-LS as neighbors or they use something >>> alternate like e.g. BFD (or nothing at all possibly) and at this point it >>> will become really weird to carry in BGP-LS an L1 tunnel which does not >>> have IGP adjacency on it ... >>> >>> open to suggestions but AFAIS the FR/client L2 adjacencies are in BGP-LS >>> already per normal procedures (and the fact that you see client/reflector >>> flag on both nodes & cluster ID allows you to derive the property of the >>> adjacency) but the L1 mesh (if used) has no business in BGP-LS unless it >>> forms IGP L1 adjacencies. >>> >>> -- tony >>> >>> On Wed, Jun 22, 2022 at 3:26 PM Ketan Talaulikar <ketant.i...@gmail.com> >>> wrote: >>> >>>> Hi Jordan, >>>> >>>> Thanks for your response and please check inline below for what needs >>>> further discussion. >>>> >>>> >>>> On Tue, Jun 21, 2022 at 11:10 PM Jordan Head <jh...@juniper.net> wrote: >>>> >>>>> Hi Ketan, >>>>> >>>>> >>>>> >>>>> Thanks for reading the draft and taking the time to comment. >>>>> >>>>> >>>>> >>>>> [Ketan] >>>>> >>>>> *1) The status of this should also be experimental so it is aligned >>>>> with the IGP spec.* >>>>> >>>>> >>>>> >>>>> [Jordan] >>>>> >>>>> As Sue said, good catch, I’ll update this draft to align with the >>>>> other draft. >>>>> >>>>> >>>>> >>>>> [Ketan] >>>>> >>>>> *2) Though not strictly required, I would suggest adding some text >>>>> that covers the description/motivation for adding this into BGP-LS - >>>>> perhaps a use case or scenario. Normally, the TE use cases are obvious but >>>>> I am unable to understand the motivation in this case. As an example, we >>>>> don't have an equivalent of OSPFv2 Type 4 LSA information being signaled >>>>> into BGP-LS - just because there was no pressing need for it. There are a >>>>> few other such IGP extensions not exposed to BGP-LS ... but I don't want >>>>> to >>>>> give more ideas ;-)* >>>>> >>>>> >>>>> >>>>> [Jordan] >>>>> >>>>> I see your point, my answers to #5 and #6 should hopefully make things >>>>> more obvious. >>>>> >>>>> >>>>> >>>>> [Ketan] >>>>> >>>>> *3) Reference to RFC8714 is required in addition to RFC2119.* >>>>> >>>>> >>>>> >>>>> [Jordan] >>>>> >>>>> I assume you mean RFC8174. Good catch, I’ll add it. >>>>> >>>>> >>>>> >>>>> [Ketan] >>>>> >>>>> *4) It would be more appropriate to name this TLV as IS-IS Flood >>>>> Reflection TLV, unless there was some plan to introduce similar for OSPF.* >>>>> >>>>> >>>>> >>>>> [Jordan] >>>>> >>>>> Sure, I’ll update it accordingly. >>>>> >>>>> >>>>> >>>>> [Ketan] >>>>> >>>>> *5) The IS-IS TLV has sub-TLVs but that has not been defined for >>>>> BGP-LS. Why?* >>>>> >>>>> >>>>> >>>>> *6) Why just this one TLV and not the others from the IS-IS spec? >>>>> Perhaps the use case (my comment (2)) below can help justify why only this >>>>> one is required and not the others? Another reason why, IMHO, it is better >>>>> to keep this extension in the fridge until someone really needs it as an >>>>> ingredient to cook a deployment solution. * >>>>> >>>>> >>>>> >>>>> [Jordan] >>>>> >>>>> #5 and #6 seem quite similar, so I’ll combine my >>>>> answers. >>>>> >>>>> >>>>> >>>>> The other TLVs are for auto-discovery signal that a node is *capable *of >>>>> FR and to signal a potential *desire* to automatically create tunnels >>>>> between nodes. An operator may choose to use that functionality or simply >>>>> configure things manually. Regardless of which option is used, we need to >>>>> be able to describe the *operational* IGP state rather than *desired* >>>>> state as the two may not necessarily align. >>>>> >>>> >>>> KT> The operational IGP info is what is advertised in BGP-LS. So you >>>> are saying that the Flood Reflection Discovery Sub-TLV is also good to >>>> get into BGP-LS so the controller can see which devices have the capability >>>> (+config) to participate as reflector/client? >>>> >>>> >>>>> >>>>> >>>>> The existing BGP-LS descriptors along with what’s being proposed in >>>>> the draft should suffice for describing IS-IS Flood Reflection information >>>>> in a way that’s useful for a controller. For example, which nodes belong >>>>> to >>>>> which Flood Reflection cluster and their role within that cluster >>>>> (Reflector or Client). From this, the controller can derive what’s >>>>> relevant >>>>> for TE-paths on top of the Flood Reflection topology. >>>>> >>>> >>>> KT> Isn't the tunnel advertisement and its status (i.e. whether an >>>> adjacency is formed over it) also equally important/essential. I don't >>>> claim to have read/followed the flood reflection work very closely, but my >>>> high-level understanding was that if a controller needs to >>>> understand/monitor IGP topologies with this feature enabled, it would need >>>> to know of all of these aspects? >>>> >>>> Thanks, >>>> Ketan >>>> >>>> >>>>> >>>>> >>>>> Thank you >>>>> >>>>> Jordan Head >>>>> >>>>> >>>>> >>>>> *From: *Idr <idr-boun...@ietf.org> on behalf of Susan Hares < >>>>> sha...@ndzh.com> >>>>> *Date: *Thursday, June 16, 2022 at 1:14 PM >>>>> *To: *Ketan Talaulikar <ketant.i...@gmail.com> >>>>> *Cc: *"i...@ietf.org" <i...@ietf.org> >>>>> *Subject: *Re: [Idr] draft-head-idr-bgp-ls-isis-fr-01 - WG adoption >>>>> call (6/6 to 6/20) >>>>> >>>>> >>>>> >>>>> *[External Email. Be cautious of content]* >>>>> >>>>> >>>>> >>>>> Ketan: >>>>> >>>>> >>>>> >>>>> I encouraged the authors to add this to the LSR document – >>>>> >>>>> since a short LSR+IDR WG LC would be less efforts. >>>>> >>>>> The authors may still consider this pathway to RFC. >>>>> >>>>> >>>>> >>>>> Thank you for mention the experimental status, and your >>>>> >>>>> References. >>>>> >>>>> >>>>> >>>>> Sue >>>>> >>>>> >>>>> >>>>> *From:* Ketan Talaulikar <ketant.i...@gmail.com> >>>>> *Sent:* Thursday, June 16, 2022 11:19 AM >>>>> *To:* Susan Hares <sha...@ndzh.com> >>>>> *Cc:* i...@ietf.org >>>>> *Subject:* Re: [Idr] draft-head-idr-bgp-ls-isis-fr-01 - WG adoption >>>>> call (6/6 to 6/20) >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> Hi Sue, >>>>> >>>>> >>>>> >>>>> To begin with, I would very much prefer that the authors consider >>>>> folding this (and other such IGP extensions) into the LSR document into a >>>>> section that covers BGP-LS. I understand that the LSR document is past >>>>> WGLC >>>>> but it still has a way to go through review cycles and it would be simpler >>>>> and more efficient to just add BGP-LS encoding to it, then do a short >>>>> LSR+IDR WGLC review and get it off to the IESG. >>>>> >>>>> >>>>> >>>>> Either way, the document perhaps needs some updates before considering >>>>> adoption, and please see the comments below. >>>>> >>>>> >>>>> >>>>> 1) The status of this should also be experimental so it is aligned >>>>> with the IGP spec. >>>>> >>>>> >>>>> >>>>> 2) Though not strictly required, I would suggest adding some text that >>>>> covers the description/motivation for adding this into BGP-LS - perhaps a >>>>> use case or scenario. Normally, the TE use cases are obvious but I am >>>>> unable to understand the motivation in this case. As an example, we don't >>>>> have an equivalent of OSPFv2 Type 4 LSA information being signaled into >>>>> BGP-LS - just because there was no pressing need for it. There are a few >>>>> other such IGP extensions not exposed to BGP-LS ... but I don't want to >>>>> give more ideas ;-) >>>>> >>>>> >>>>> >>>>> 3) Reference to RFC8714 is required in addition to RFC2119. >>>>> >>>>> >>>>> >>>>> 4) It would be more appropriate to name this TLV as IS-IS Flood >>>>> Reflection TLV, unless there was some plan to introduce similar for OSPF. >>>>> >>>>> >>>>> >>>>> 5) The IS-IS TLV has sub-TLVs but that has not been defined for >>>>> BGP-LS. Why? >>>>> >>>>> >>>>> >>>>> 6) Why just this one TLV and not the others from the IS-IS spec? >>>>> Perhaps the use case (my comment (2)) below can help justify why only this >>>>> one is required and not the others? Another reason why, IMHO, it is better >>>>> to keep this extension in the fridge until someone really needs it as an >>>>> ingredient to cook a deployment solution. >>>>> >>>>> >>>>> >>>>> Thanks, >>>>> >>>>> Ketan >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> On Tue, Jun 7, 2022 at 2:58 AM Susan Hares <sha...@ndzh.com> wrote: >>>>> >>>>> This begins a 2 week WG adoption call for >>>>> draft-head-idr-bgp-ls-isis-fr-01.txt >>>>> >>>>> >>>>> >>>>> https://datatracker.ietf.org/doc/draft-head-idr-bgp-ls-isis-fr/ >>>>> <https://urldefense.com/v3/__https:/datatracker.ietf.org/doc/draft-head-idr-bgp-ls-isis-fr/__;!!NEt6yMaO-gk!G0PFxaJ1ZzmvYpV3_4DwRvuQa3J8Gs5m5MjESxwy-w_j-LGYRGbLxd_IMiufXqtLO0swOuqYO3T9$> >>>>> >>>>> >>>>> >>>>> This document defines one new BGP-LS (BGP Link-State) TLV for >>>>> >>>>> Flood Reflection to match the ISIS TLV for flood reduction. >>>>> >>>>> >>>>> >>>>> The draft is short (5 total pages). >>>>> >>>>> >>>>> >>>>> Since this BGP-LS feature has been adopted by IS-IS, >>>>> >>>>> Please consider >>>>> >>>>> >>>>> >>>>> 1. Is there any technical difficulty with adding this to the >>>>> BGP-LS code points? >>>>> >>>>> 2. Is this draft ready for publication? >>>>> >>>>> 3. Does this addition help operational networks. >>>>> >>>>> >>>>> >>>>> Cheers, Sue Hares >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> _______________________________________________ >>>>> Idr mailing list >>>>> i...@ietf.org >>>>> https://www.ietf.org/mailman/listinfo/idr >>>>> <https://urldefense.com/v3/__https:/www.ietf.org/mailman/listinfo/idr__;!!NEt6yMaO-gk!G0PFxaJ1ZzmvYpV3_4DwRvuQa3J8Gs5m5MjESxwy-w_j-LGYRGbLxd_IMiufXqtLO0swOsvomuzp$> >>>>> >>>>> >>>>> Juniper Business Use Only >>>>> >>>> _______________________________________________ >>>> Idr mailing list >>>> i...@ietf.org >>>> https://www.ietf.org/mailman/listinfo/idr >>>> >>>
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