Hi, Les: I know you are the main person that guards the improvement of IS-IS protocol, but the liveness of this protocol should be from various contributions. I admire your opinions, but think you should be more flexible to hear/adopt other options.
What I worry is that do we need the seemed generalized solution to the one mentioned use case in current stage? I think the basis to approach this direction is not mature until now. Let's give you one example that you have developed(please do not angry): https://datatracker.ietf.org/doc/html/rfc6823 (December 2010) describe the "GENINFO TLV" to transfer the application information within the ISIS, but until now, only one application ID(1 for TRILL) is defined out of the reserved 65535 values. I will not expand the history and future of RFC6823. What I want to do is that we do not repeat its experiences. One additional comments, the PUA draft has been updated based on the comments/suggestions from the LSR experts, it has passed several rounds reviews of the LSR WG members. We can focus to solve your remaining concerns later. Let's first hear more opinions from other experts on the direction to solve this problem. We all agree it can and should be solved via IGP protocol. Best Regards Aijun Wang China Telecom -----Original Message----- From: lsr-boun...@ietf.org <lsr-boun...@ietf.org> On Behalf Of Les Ginsberg (ginsberg) Sent: Thursday, October 14, 2021 1:25 PM To: Aijun Wang <wangai...@tsinghua.org.cn>; 'Les Ginsberg (ginsberg)' <ginsberg=40cisco....@dmarc.ietf.org>; 'Acee Lindem (acee)' <acee=40cisco....@dmarc.ietf.org>; 'Peter Psenak' <ppsenak=40cisco....@dmarc.ietf.org>; lsr@ietf.org Subject: Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification" Aijun - I appreciate the continued dialogue. You no doubt remember that Peter and I discussed PUA with you and co-authors several times over the years (at your kind invitation) - even before you had submitted the draft. We raised the same concerns with you then that I have mentioned earlier in this thread. None of the changes you have made have altered the basic mechanism that you use - so my objections remain the same. And that isn’t going to change...I don’t think PUA is a good solution. The rest of your argument seems to be that we should move forward w the PUA solution just because the draft has been around for a long time. Sorry, that isn’t a valid argument. Either the WG thinks PUA is good solution or it doesn't - that is the only basis on which a decision to adopt/not adopt should be made. The fact that you keep refreshing/updating the draft carries no weight. Les > -----Original Message----- > From: Lsr <lsr-boun...@ietf.org> On Behalf Of Aijun Wang > Sent: Wednesday, October 13, 2021 7:50 PM > To: 'Les Ginsberg (ginsberg)' <ginsberg=40cisco....@dmarc.ietf.org>; > 'Acee Lindem (acee)' <acee=40cisco....@dmarc.ietf.org>; 'Peter Psenak' > <ppsenak=40cisco....@dmarc.ietf.org>; lsr@ietf.org > Subject: Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and > OSPF Extension for Event Notification" > > Hi, Les: > > Thanks for your invitation. We are considering how to merge our > directions to the same aim. > > The reason that we want to finalize the PUA solution is due to it has > been discussed intensely on the previous IETF meetings and on the mail > list.(we start the discussion on October 2019, two years passed, now > in version 07) We have changed and updated the draft a lot to reflect > the comments from the LSR experts, including the comments from you. > The use cases, solution procedures are almost finished, then we think > it is time to start the adoption call for PUA draft. > For the remaining questions, we think we have plenty of time to solve > it after the adopt > > But for "IS-IS and OSPF Extension for Event Notification" draft, it > just began the travel for the standardization activities. > I think it is one alternative solution to the PUA draft, but as we > have seen the comments on the list, whether to open the gate for the > event notification mechanism within IGP is needed to further intense > discussion. > There may be some hidden problems has not been investigated for this > direction. > > And, there is no any restriction within IETF that we should rely on > one solution to solve the same problem. Think about how many solutions > exist for the Traffic Engineering requirements? > Even within LSR WG, we have flooding reduction, flooding reflection > and TTZ solutions for the similar problems. > > We have never mixed them for discussion and compare. There is seldom > solutions can satisfy all our preferences. > > So, in conclusion, I recommend to standardize firstly the PUA draft, > and then to discuss whether to open the gate for the event > notification mechanism within IGP. > Anyway, for the general solution, currently we have only the same use > case in mind as that in PUA draft. > > We are also kind to invite you, Peter, Acee to participate the PUA > solution, to solve the problems that you are worrying. Other LSR > experts(Tony Li, Greg, Robert, Jeff etc.) are also welcome The design, > implementation, deployment experiences of PUA mechanism can certainly > give the guides for the more general solution for further notification > event. > And, I still think PUA solution is the easiest way to solve the > problem, I think all of your concerning points will emerge later in > "IS-IS and OSPF Extension for Event Notification" draft. > > > Best Regards > > Aijun Wang > China Telecom > > -----Original Message----- > From: lsr-boun...@ietf.org <lsr-boun...@ietf.org> On Behalf Of Les > Ginsberg (ginsberg) > Sent: Thursday, October 14, 2021 2:44 AM > To: Acee Lindem (acee) <acee=40cisco....@dmarc.ietf.org>; Peter Psenak > <ppsenak=40cisco....@dmarc.ietf.org>; lsr@ietf.org > Subject: Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and > OSPF Extension for Event Notification" > > This thread is becoming "diverse". > We are trying to talk about many different solutions (IGP, BGP, BFD) - > all of which may be useful and certainly are not mutually exclusive. > > If we can agree that an IGP solution is useful, then we can use this > thread to set a direction for the IGP solution - which seems to me to > be something we should do independent of whether the other solutions are also > pursued. > > With that in mind, here is my input on the IGP solutions: > > PUA > ------- > > For me, the solution has two major drawbacks: > > 1)It tries to repurpose an existing (and fundamental) Reachability > Advertisement into an UnReachability advertisement under certain > conditions > > The interoperability risks associated with this make me very reluctant > to go down this path. > And the use of the same advertisement to indicate Reachability and > Unreachability is IMO highly undesirable. > > 2)The withdrawal of the "Unreachability Advertisement" after some > delay (which is necessary) remains problematic despite the authors > attempts to address thus > > Event Notification > ------------------------ > > This avoids the drawbacks of PUA and is flexible enough to handle > future and unforeseen types of notifications. > > I would like to extend the offer already made by Peter to the authors > of PUA to join us and work on the Event Notification draft. > The authors of PUA certainly deserve credit for raising awareness of > the problem space and it would be good to have them working with us on > a single IGP solution. > > But PUA is not an alternative that I can support. > > Les > > > -----Original Message----- > > From: Lsr <lsr-boun...@ietf.org> On Behalf Of Acee Lindem (acee) > > Sent: Wednesday, October 13, 2021 9:49 AM > > To: Peter Psenak <ppsenak=40cisco....@dmarc.ietf.org>; lsr@ietf.org > > Subject: Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and > > OSPF Extension for Event Notification" > > > > Hi Peter, > > > > See inline. > > > > On 10/13/21, 4:42 AM, "Peter Psenak" > > <ppsenak=40cisco....@dmarc.ietf.org> wrote: > > > > Hi Acee, > > > > On 12/10/2021 21:05, Acee Lindem (acee) wrote: > > > Speaking as WG Chairs: > > > > > > The authors of “Prefix Unreachable Announcement” have > > requested > an > > > adoption. The crux of the draft is to signal unreachability of a > > prefix > > > across OSPF or IS-IS areas when area summarization is employed and > > > prefix is summarised. We also have “IS-IS and OSPF Extension for Event > > > Notification” which can be used to address the same use case. > > The > drafts > > > take radically different approaches to the problem and the authors of > > > both drafts do not wish to converge on the other draft’s method so it > > is > > > understandable that merging the drafts really isn’t an option. > > > > just for the record, I offered authors of "Prefix Unreachable > > Announcement" co-authorship on "Event notification" draft, arguing the > > the event base solution addresses their use case in a more elegant and > > scalable way. They decided to push their idea regardless. > > > > One solution to this problem would have definitely been better. > > > > > Before an adoption call for either draft, I’d like to ask the WG: > > > > > > 1. Is this a problem that needs to be solved in the IGPs? The use > > case > > > offered in both drafts is signaling unreachability of a BGP peer. > > > Could this better solved with a different mechanism (e.g., BFD) > > > rather than flooding this negative reachability information across > > > the entire IGP domain? > > > > we have looked at the various options. None of the existing ones would > > fit the large scale deployment with summarization in place. Using BFD > > end to end to track reachability between PEs simply does not scale. > > > > It seems to me that scaling of BFD should be "roughly" proportional > > to BGP session scaling but I seem to be in the minority. My opinion > > is based on SDWAN tunnel scaling, where BFD is used implicitly in > > our solution. How many other PEs does a BGP edge PE maximally peer with? > > Thanks, > > Acee > > > > > > Some people believe this should be solved by BGP, but it is important to > > realize that while the problem statement at the moment is primarily > > targeted for egress PE reachability loss detection for BGP, the > > mechanism proposed is generic enough and can be used to track > > the > peer > > reachablity loss for other cases (e.g GRE endpoint, etc) that do not > > involve BGP. > > > > We went even further and explored the option to use completely out of > > band mechanism that do not involve any existing protocols. > > > > Simply, the advantage of using IGP is that it follows the existing MPLS > > model, where the endpoint reachability is provided by IGPs. Operators > > are familiar with IGPs and know how to operate them. > > > > On top of the above, IGP event notification can find other use cases in > > the future, the mechanism defined in draft is generic enough. > > > > > > > 2. Assuming we do want to take on negative advertisement in the IGP, > > > what are the technical merits and/or detriments of the two > > approaches? > > > > we have listed some requirements at: > > > > > > https://datatracker.ietf.org/doc/html/draft-ppsenak-lsr-igp-event- > > notification-00#section-3 > > > > From my perspective the solution should be optimal in terms of amount > > of data and state that needs to be maintained, ideally separated from > > the traditional LS data. I also believe that having a generic mechanism > > to distribute events has it own merits. > > > > thanks, > > Peter > > > > > > > > We’ll reserve any further discussion to “WG member” comments > > on the two > > > approaches. > > > > > > Thanks, > > > Acee and Chris > > > > > > > > > _______________________________________________ > > Lsr mailing list > > Lsr@ietf.org > > https://www.ietf.org/mailman/listinfo/lsr > _______________________________________________ > Lsr mailing list > Lsr@ietf.org > https://www.ietf.org/mailman/listinfo/lsr > > _______________________________________________ > Lsr mailing list > Lsr@ietf.org > https://www.ietf.org/mailman/listinfo/lsr _______________________________________________ Lsr mailing list Lsr@ietf.org https://www.ietf.org/mailman/listinfo/lsr _______________________________________________ Lsr mailing list Lsr@ietf.org https://www.ietf.org/mailman/listinfo/lsr
