Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

Hi, Tony: Yes, we should find the least cost to solve the problem. The mentioned failure prefixes/loopback will only be advertised under some conditions. The ABR should have such controls, as described in https://datatracker.ietf.org/doc/html/draft-wang-lsr-prefix-unreachable-annoucement-07#

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

Les, If you’re advertising loopbacks that are outside of the summarized space, then you end up with reachability and liveness. Yes, there’s a cost in scalability… it ain’t free. Tony > On Oct 13, 2021, at 10:36 PM, Les Ginsberg (ginsberg) > wrote: > > Tony – > > Given that IGPs provide

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

Tony – Given that IGPs provide the ability to advertise summaries (in the interest of scalability), I think it is reasonable to say that being able to advertise reachability changes of endpoints covered by the summary also can be considered as a legitimate use of the IGP. IGPs certainly adverti

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

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

Hi Gyan, I fully understand the request. I still question whether it should be solved by routing. This is not a path computation problem. It’s reachability and more significantly, liveness. That really seems like it’s looking for a slightly different architectural tool. Yours in IS-IS, Tony

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

Hi Greg PUA Section 5 really helps describe a primary use case for both PUA and event notification draft, tracking of egress PE BGP next hop attribute component prefixes that are part of a summary and I used the example of RFC 5283 MPLS LDP Inter-area extension LPM matching but can apply to any us

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 y

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

Hi Gyan, thank you for the most detailed information. With the addition of the single-hop BFD the puzzle is complete. Or almost complete. What I am wondering, is the fact that a PE is likely to be a part of a mesh network that provides more resilient service. As a result, a single BFD session going

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

Hi Tony This is a real world problem for large scale networks where an service providers core network is broken up into OSPF areas or ISIS levels and each PEs loopback BGP next hop attribute for 1000s of PEs within an area are summarized at the P router ASBR ISIS L1-2 router or OSPF ABR and the n

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

Hi, I’ve said it many times before, in many different venues: “BGP is not a dump truck!”. Is the fact that I didn’t mention the IGPs taken as some indication that they are fair game? No, the IGPs aren’t a dump truck either. We have a clear, unambiguous way of signaling individual system ou

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

Hi Greg This draft would utilize the same IGP optimizations used today such as IGP single hop BFD for core link failure detection tuning down to sub second. Most modern routers LC’s are to process BFD control packet processing in hardware. We are assuming all typical optimizations are in utilized

[Lsr] Looking for feedback of using Flex Algo to advertise the 5G edge computing associated metrics

LSR experts: We have updated the draft to reflect the suggestions from LSR WG to use Flex Algo to advertise the metrics associated with the environment where 5G edge computer servers are running. https://datatracker.ietf.org/doc/draft-dunbar-lsr-5g-edge-compute/ In a nutshell, the draft propos

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

Hi Greg, One thing to consider here is that this is not E2E OAM notification. Based on the discussion of scale, there could be 1000+ remote PEs that need to know about the outage. Also, as Peter pointed out, the target audience is a proper audience of the IGP routers receiving the summary advert

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

Hi Les, Indeed "for the given use case that amount/rate of traffic would be unusual." that is completely right and that is why I said to Peter that I will support this draft if it comes to WG adoption. But what is the mechanism the gate will stop to only allow light event notification like PE dow

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

Speaking from the deepest, darkest depths of WG membership: Again, assuming that putting this unreachability information in the IGPs is a good idea, here are the things I like an don't like about "IGP Event Notification" I like the fact that it reflects the ephemeral context of a route becoming

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

Hi Les, thank you for your consideration of my note. No, I am not saying "never". I agree with you that extending the discussion on the applicability of the proposed solution is helpful. Looking forward to that. Regards, Greg On Wed, Oct 13, 2021 at 3:14 PM Les Ginsberg (ginsberg) wrote: > Greg

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

Robert – You are (of course) right. But the question is whether it is worth the effort to define a specific flooding topology for this use case? If the answer to that is “yes”, then I think a BGP solution would probably make more sense. Alternatively, we could use a separate IGP instance for th

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

Greg – The draft is introducing a new IGP mechanism to signal events. That does not mean that it should be used for any and all event notifications. We don’t discuss the latter point in any detail in the draft – but it is only V-00. 😊 The first use case (described in Section2) seems very approp

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

Speaking as a mere WG member... Assuming that there are enough remote PEs that need this unreachability information and we want to use the IGPs for this, here is what I don't like about PUA (Les has taken away much of my thunder __): 1. Usage of the prefix-originator for unreachability not

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

Hi Les, I agree with all you said except this: *The nodes to whom this information needs to be flooded are the same nodes which have received the summary address advertisement.* I really do not think so. Only a subset of nodes which received IGP summary route may need to know about the failures

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

Peter, Not “ALL” but these that share a service (import each other routes). I agree that this is a brute force solution that isn’t necessarily to win a beauty contest. However this is deployable and implementable. Back to LSR scoop ;-) in general i agree with Les’ points Cheers, Jeff > On Oct

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

Hi Les, et al., I've just read the draft-ppsenak-lsr-igp-event-notification. Event notification is usually viewed as the function of the Fault Management OAM, not of a control plane protocol. Thus, I find the idea of using an IGP protocol to distribute event notifications troubling. One of my conce

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

Robert – Inline. From: Robert Raszuk Sent: Wednesday, October 13, 2021 12:52 PM To: Les Ginsberg (ginsberg) Cc: Acee Lindem (acee) ; Peter Psenak (ppsenak) ; lsr@ietf.org Subject: Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification" Hi Les, > If

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

Hi Les, > If we can agree that an IGP solution is useful, then we can use this thread to > set a direction for the IGP solution I think this thread aimed to answer both of those questions hence some comments. But even if we assume that Event Flooding via IGP have a valid use case (regardless if

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

Hi Jeff, On 13/10/2021 19:28, Jeff Tantsura wrote: Number of BGP peers isn’t representative here, classical deployments would have a number of RR’s to circumvent full mesh. What counts is the total number of PEs (next-hops) that originate the prefix that is locally imported (needs to be tracke

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 - whi

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

Jeff, The point is about the right architecture, not a brute force method. Do you see it as elegant to bombard 1000s PE with a probe every second ? I do not. Especially considering that PEs rarely go down. And that should be compared with even driven notification. BGP: - Local BFD detect the fa

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

Number of BGP peers isn’t representative here, classical deployments would have a number of RR’s to circumvent full mesh. What counts is the total number of PEs (next-hops) that originate the prefix that is locally imported (needs to be tracked). For further optimization, only multihomed prefixe

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

Below .. > > *From: *Robert Raszuk > *Date: *Wednesday, October 13, 2021 at 1:16 PM > *To: *Acee Lindem > *Cc: *"Peter Psenak (ppsenak)" , "lsr@ietf.org" < > lsr@ietf.org> > *Subject: *Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and > OSPF Extension for Event Notification" > > > > >

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

From: Robert Raszuk Date: Wednesday, October 13, 2021 at 1:16 PM To: Acee Lindem Cc: "Peter Psenak (ppsenak)" , "lsr@ietf.org" Subject: Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification" > How many other PEs does a BGP edge PE maximally peer wi

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

> How many other PEs does a BGP edge PE maximally peer with? Typically on IBGP side you will see 2-4 peers. Those are RRs. Due to no autodiscovery of BGP sessions no many people do iBGP full mesh between PEs. Best, R. On Wed, Oct 13, 2021 at 6:48 PM Acee Lindem (acee) wrote: > Hi Peter, > > S

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" 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

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

Hi Peter, I am familiar with solutions that guarantee sub-second defect detection in an IGP domain. But these are based on the single-hop BFD. Do you mean that a standard-based IGP without any BFD involvement can guarantee sub-second detection of a failure in the domain? Would be interesting to lea

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

Dear Aijun, Let me reply to other your other comments ... > In both cases such an event will likely be detected using BFD (if we are > talking about unreachability of a BGP or IGP peer). > > *[WAJ] No. Link or Node Failures are not detected via BFD within one IGP > domain. It just rely on the no

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

Greg, On 13/10/2021 15:36, Greg Mirsky wrote: Hi Aijun, thank you for your quick response. Please find my further notes in-line below tagged GIM>>. Regards, Greg On Tue, Oct 12, 2021 at 9:06 PM Aijun Wang > wrote: Hi, Greg: __ __ The defe

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

Hi Aijun, thank you for your quick response. Please find my further notes in-line below tagged GIM>>. Regards, Greg On Tue, Oct 12, 2021 at 9:06 PM Aijun Wang wrote: > Hi, Greg: > > > > The defect detection time should be same as the IGP flooding speed. > GIM>> I think that that would not be t

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

Hi Robert, On 13/10/2021 12:23, Robert Raszuk wrote: Hi Peter, In your example of GRE between PEs .. what is the purpose of this GRE ? Isn't it to connect services advertised via BGP ? not necessarily. There are providers that provide L2/L3 connectivity through their backbone using some s

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

*> [WAJ] No. Link or Node Failures are not detected via BFD within one IGP domain.* What makes you say so ? Thx, R. On Wed, Oct 13, 2021 at 3:27 AM Aijun Wang wrote: > Hi, Robert: > > > > Answers to your comments are inline below. > > > > > > Best Regards > > > > Aijun Wang > > China Telecom

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

Hi Peter, In your example of GRE between PEs .. what is the purpose of this GRE ? Isn't it to connect services advertised via BGP ? In any case perhaps one size does not fit all. Maybe some networks can use BGP signalling (withdraws), maybe other will like to see bad even notification in IGPs. C

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

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

Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification"

Hi Acee, This solution is mainly used for the Edge PEs. In most cases, the performance of the edge PE is poor. We may not have so much BFD resources to do detection. When we do aggregate for remote PE’s locator route, the Edge PE will only detect remote PE’s failure on BGP neighbors’ down and r