Your previous responses at here 
https://mailarchive.ietf.org/arch/msg/lsr/EFb71fc-hc-_oMCnksOZfSPt0-o/ is also 
for Case 2.
Where your responses for Case 1?
Please give the link.

Or else, it will be registered for further clarification.

-----邮件原件-----
发件人: Peter Psenak [mailto:[email protected]] 
发送时间: 2025年5月28日 16:48
收件人: Aijun Wang <[email protected]>; 'Gunter van de Velde (Nokia)' 
<[email protected]>
抄送: [email protected]
主题: Re: 答复: 答复: 答复: [Lsr] Re: 答复: I-D Action: 
draft-ietf-lsr-igp-ureach-prefix-announce-06.txt

On 28/05/2025 10:46, Aijun Wang wrote:
> OK, you say Gunter talk about the Case 2. It's no problem.
>
> Then, what's your considerations of Case 1?

I have already responded to that. I'm done with this thread.

Peter

>
> -----邮件原件-----
> 发件人: Peter Psenak [mailto:[email protected]]
> 发送时间: 2025年5月28日 16:40
> 收件人: Aijun Wang <[email protected]>; 'Gunter van de Velde 
> (Nokia)' <[email protected]>
> 抄送: [email protected]
> 主题: Re: 答复: 答复: [Lsr] Re: 答复: I-D Action: 
> draft-ietf-lsr-igp-ureach-prefix-announce-06.txt
>
> On 28/05/2025 10:24, Aijun Wang wrote:
>> Hi, Peter:
>>
>> We are talking about when to switch back to the remote failure PE, not 
>> switch from it.
>>
>> In Case 1, when UPA advertise for a configured time to "allows BGP to 
>> converge after the remote PE failure ", then ABR stop advertising UPA, right?
>> At this moment, should the receiver switch back BGP PIC to the previous 
>> failure PE?
> it can not switch back to failed PE, because BGP on remote nodes know that 
> such PE does not exist anymore - e.g. BGP has converged.
>
>> According to Gunter's logic, it should switch back to the previous failure 
>> PE, because the summary address indicates the specific failure PE is 
>> reachable again.
> Gunter was talking about the case, where the remote PE loopback prefix 
> reachability was recovered shortly after the UPA was generated, so there 
> would still be a valid BGP path via such PE.
>
> Peter
>
>
>> What's your thought?
>>
>>
>> Best Regards
>>
>> Aijun Wang
>> China Telecom
>>
>> -----邮件原件-----
>> 发件人: Peter Psenak [mailto:[email protected]]
>> 发送时间: 2025年5月28日 16:10
>> 收件人: Aijun Wang <[email protected]>; 'Gunter van de Velde 
>> (Nokia)' <[email protected]>
>> 抄送: [email protected]
>> 主题: Re: 答复: [Lsr] Re: 答复: I-D Action:
>> draft-ietf-lsr-igp-ureach-prefix-announce-06.txt
>>
>> On 28/05/2025 09:35, Aijun Wang wrote:
>>> Hi, Gunter:
>>>
>>> I don’t recommend to design one " brand-new control plane signal " to 
>>> signal the prefix reachability.
>>>
>>> What I argue with you until now, is the following statements:
>>> "when a UPA stops being advertised, that unreachability signal goes away, 
>>> and at that point, the summary route takes over and signals reachability."
>>>
>>>    From the UPA document, we can know there at least two reasons can lead 
>>> the "UPA stops being advertised":
>>> Case 1: "UPA advertisements SHOULD therefore be withdrawn after some amount 
>>> of time, that would provide sufficient time for UPA to be flooded 
>>> network-wide and acted upon by receiving nodes, but limits the presence of 
>>> UPA in the network."
>>> Case 2: " ABR or ASBR MUST withdraw the previously advertised UPA when the 
>>> reason for which the UPA was generated was lost "
>>>
>>> Then, if the reason that lead " UPA stops being advertised " is Case 1, 
>>> then your logic that " at that point, the summary route takes over and 
>>> signals reachability." is wrong.
>>> When the BGP PIC FRR switch back at this moment, the traffic will be lost.
>> no.
>>
>> The draft also says:
>>
>> "The time the UPA is kept in the network SHOULD also reflect the intended 
>> use-case for which the UPA was advertised."
>>
>> For BGP PIC, you need to keep it for a time that allows BGP to converge 
>> after the remote PE failure.
>>
>> Peter
>>
>>
>>> Best Regards
>>>
>>> Aijun Wang
>>> China Telecom
>>>
>>> -----邮件原件-----
>>> 发件人: [email protected]
>>> [mailto:[email protected]] 代表 Gunter van de Velde (Nokia)
>>> 发送时间: 2025年5月28日 15:04
>>> 收件人: Aijun Wang <[email protected]>
>>> 抄送: [email protected]; 'Peter Psenak' <[email protected]>
>>> 主题: [Lsr] Re: 答复: I-D Action:
>>> draft-ietf-lsr-igp-ureach-prefix-announce-06.txt
>>>
>>> [speaking as work group participant]
>>>
>>> Hi Aijun,
>>>
>>> Let’s wrap up this thread. I feel we’ve explored this topic quite 
>>> thoroughly from different angles, and I’d prefer not to keep circling back 
>>> and repeating the same points.
>>> (this is my last email on this thread)
>>>
>>> Regarding your comment:
>>> "
>>> 1) The data-plane OAM tools(BFD, ICMP, STAMP, and TWAMP) should be used to 
>>> test and verify the prefix reachability.
>>>      Along the evolution of PUAM/UPA drafts, there are lots of discussions 
>>> among the efficiency of these OAM tools, versus the PUAM/UPA mechanism.
>>>      I think you may miss these previous discussions.
>>>      Here I want just to say, if the WG agree with you, the PUAM/UPA draft 
>>> shouldn't be existed.
>>> "
>>>
>>> Let me try to explain my point again, one last time, just in a different 
>>> way for clarity.
>>>
>>> A router forwards packets based on the unicast forwarding table, which is 
>>> typically populated by routing protocols like OSPF or IS-IS. Once a route 
>>> is selected, the router uses that information to forward packets, plain and 
>>> simple. But here’s the thing: the router doesn’t really “know” if the 
>>> packet will make it all the way to its final destination. It just follows 
>>> the best path it has available, based on its local view. What happens 
>>> downstream, packet drops, blackholing, filtering, or misrouting. can’t be 
>>> predicted by the control plane alone. That’s just the reality of 
>>> distributed routing.
>>>
>>> At the end of the day, if we really want to be sure something is reachable 
>>> and working as expected, the best way to confirm that is to actually test 
>>> it.
>>> Tools like BFD, ICMP, STAMP, and TWAMP are exactly what we use to validate 
>>> that, since they measure actual behavior in the data plane.
>>>
>>>    From your comments, it sounds like you're proposing a new control plane 
>>> signal that says, “Hey, trust me, I’m really reachable.” But I’m not 
>>> convinced such a signal would be any more reliable than the routes we 
>>> already learn through established routing protocols like OSPF or IS-IS. 
>>> That kind of new control plane signal could still be based on outdated, 
>>> incorrect, or incomplete information, and wouldn’t really help when it 
>>> comes to truly assessing data plane reachability.
>>>
>>> Coming back to UPA. When using UPA the procedure as described in [1], [2], 
>>> and [3] is predictable and behaves in an operationally efficient way. That 
>>> way, in most cases, we don’t even need to rely on OAM data plane testing 
>>> tools. From my point of view, adding a new control plane message to somehow 
>>> validate reachability on top of an already installed unicast route doesn’t 
>>> really add much value. Instead, it risks introducing more complexity 
>>> without solving a real problem.
>>>
>>> Regarding your comment:
>>> "
>>> 2) In BGP PIC FRR scenario, when the router stops receiving the UPA signal, 
>>> and "switching back to the primary egress router" is wrong.
>>>      As stated in your reply, stop receiving the UPA signal " ...doesn’t 
>>> imply anything about whether the prefix is reachable ", then, when the 
>>> prefix is still unreachable, switch back to the primary egress router
>>>      will result in the traffic black hole.
>>> "
>>>
>>> GV> If the UPA disappears then the assumption is that the prefix is indeed 
>>> reachable, assuming the prefix would be a member prefix covered by the 
>>> summary route. See [1],[2] and [3] for the procedure. This is basic network 
>>> behavior when using aggregate routes on ABRs. If this is not the behavior 
>>> desired, then an alternative is to not summarize prefixes into aggregate 
>>> prefixes (but this has other operational implications).
>>>
>>> "
>>> In summary, current UPA proposal try to signal the unreachability on 
>>> demand, but lack of the signaling mechanism to revoke such announcement on 
>>> demand.
>>> "
>>>
>>> GV> What I’m saying is pretty straightforward: when a UPA stops being 
>>> advertised, that unreachability signal goes away, and at that point, the 
>>> summary route takes over and signals reachability. Summary routes have been 
>>> used in networks for years and has worked reliably. That’s why I’m having a 
>>> hard time understanding how introducing a brand-new control plane message 
>>> to signal destination reachability would actually help. It doesn’t really 
>>> add anything new when it comes to confirming data plane reachability, and 
>>> we already have mechanisms that work well in practice.
>>>
>>> Note that this was my last email on this subject as I think we now 
>>> discussed this enough.
>>>
>>> Brgds,
>>> G/
>>> [speaking as work group participant]
>>>
>>> [1]
>>> https://mailarchive.ietf.org/arch/msg/lsr/EFb71fc-hc-_oMCnksOZfSPt0-
>>> o
>>> /
>>> {2]
>>> https://mailarchive.ietf.org/arch/msg/lsr/aAyfU1ziWTuTltmZoCGO1vht7Q
>>> k
>>> /
>>> {3]
>>> https://mailarchive.ietf.org/arch/msg/lsr/hg_v2ZAOkz5bhxE4979viIowkI
>>> U
>>> /
>>>
>>> -----Original Message-----
>>> From: Aijun Wang <[email protected]>
>>> Sent: Wednesday, May 28, 2025 3:06 AM
>>> To: Gunter van de Velde (Nokia) <[email protected]>
>>> Cc: [email protected]; 'Peter Psenak' <[email protected]>
>>> Subject: 答复: [Lsr] Re: 答复: I-D Action:
>>> draft-ietf-lsr-igp-ureach-prefix-announce-06.txt
>>>
>>>
>>> CAUTION: This is an external email. Please be very careful when clicking 
>>> links or opening attachments. See the URL nok.it/ext for additional 
>>> information.
>>>
>>>
>>>
>>> Hi, Gunter:
>>>
>>> There are two misunderstanding in your arguments:
>>> 1) The data-plane OAM tools(BFD, ICMP, STAMP, and TWAMP) should be used to 
>>> test and verify the prefix reachability.
>>>      Along the evolution of PUAM/UPA drafts, there are lots of discussions 
>>> among the efficiency of these OAM tools, versus the PUAM/UPA mechanism.
>>>      I think you may miss these previous discussions.
>>>      Here I want just to say, if the WG agree with you, the PUAM/UPA draft 
>>> shouldn't be existed.
>>>
>>> 2) In BGP PIC FRR scenario, when the router stops receiving the UPA signal, 
>>> and "switching back to the primary egress router" is wrong.
>>>      As stated in your reply, stop receiving the UPA signal " ...doesn’t 
>>> imply anything about whether the prefix is reachable ", then, when the 
>>> prefix is still unreachable, switch back to the primary egress router
>>>      will result in the traffic black hole.
>>>
>>> In summary, current UPA proposal try to signal the unreachability on 
>>> demand, but lack of the signaling mechanism to revoke such announcement on 
>>> demand.
>>>
>>>
>>> Best Regards
>>>
>>> Aijun Wang
>>> China Telecom
>>>
>>> -----邮件原件-----
>>> 发件人: Gunter van de Velde (Nokia)
>>> [mailto:[email protected]]
>>> 发送时间: 2025年5月27日 17:39
>>> 收件人: Aijun Wang <[email protected]>
>>> 抄送: [email protected]; 'Peter Psenak' <[email protected]>
>>> 主题: RE: [Lsr] Re: 答复: I-D Action:
>>> draft-ietf-lsr-igp-ureach-prefix-announce-06.txt
>>>
>>> [speaking as work group participant]
>>>
>>> A router makes its forwarding decisions based on the routes it has in the 
>>> unicast forwarding table, which are populated by the control plane. When a 
>>> packet comes in, the router looks up the destination, and if there’s a 
>>> match, it uses the forwarding info tied to the best route it has at that 
>>> moment to send the packet on its way.
>>>
>>> It is worth pointing out that the router doesn’t actually know whether the 
>>> packet will make it all the way to the final destination. It simply follows 
>>> the best available path based on local routing information. Along the way, 
>>> anything from packet filtering, DDoS mitigation, or buffer drops could 
>>> affect delivery, that’s just the nature of network behavior.
>>>
>>> If there are concerns about whether a specific destination is actually 
>>> reachable, that’s where data-plane OAM tools come in. Things like BFD, 
>>> ICMP, STAMP, and TWAMP are built specifically to test and verify 
>>> reachability beyond what the control plane can determine.
>>>
>>> To clarify something mentioned earlier when I said “when the UPA is no 
>>> longer advertised and only the summary prefix remains, the system quickly 
>>> and gracefully reverts back to the original state without any issues,” I 
>>> meant exactly that. It doesn’t imply anything about whether the prefix is 
>>> reachable, it just means the system sees the UPA is gone, and so it reverts 
>>> to whatever route is considered best in the routing table.
>>>
>>> In the case of BGP PIC FRR, that usually means switching back to the 
>>> primary egress router, depending on how the feature is configured. Whether 
>>> it actually switches back or sticks with the alternate path depends on the 
>>> specific BGP PIC settings and current network state.
>>>
>>> G/
>>> (speaking as WG participant)
>>>
>>>
>>> -----Original Message-----
>>> From: Aijun Wang <[email protected]>
>>> Sent: Tuesday, May 27, 2025 10:47 AM
>>> To: Gunter van de Velde (Nokia) <[email protected]>
>>> Cc: [email protected]; 'Peter Psenak' <[email protected]>
>>> Subject: 答复: [Lsr] Re: 答复: I-D Action:
>>> draft-ietf-lsr-igp-ureach-prefix-announce-06.txt
>>>
>>>
>>> CAUTION: This is an external email. Please be very careful when clicking 
>>> links or opening attachments. See the URL nok.it/ext for additional 
>>> information.
>>>
>>>
>>>
>>> Hi, Gunter:
>>>
>>> Here is the tricky issue:
>>> "when the UPA is no longer advertised and only the summary prefix remains, 
>>> the system quickly and gracefully reverts back to the original state 
>>> without any issues."
>>>
>>> Then, you assumes that:  when no UPA is advertised, the specific prefix is 
>>> reachable again?
>>>
>>>
>>> Best Regards
>>>
>>> Aijun Wang
>>> China Telecom
>>>
>>> -----邮件原件-----
>>> 发件人: Gunter van de Velde (Nokia)
>>> [mailto:[email protected]]
>>> 发送时间: 2025年5月27日 16:17
>>> 收件人: Aijun Wang <[email protected]>
>>> 抄送: [email protected]; Peter Psenak <[email protected]>
>>> 主题: RE: [Lsr] Re: 答复: I-D Action:
>>> draft-ietf-lsr-igp-ureach-prefix-announce-06.txt
>>>
>>> [speaking as work group participant]
>>>
>>> Hi Aijun,
>>>
>>> I just wanted to share a couple of thoughts in response to your message.
>>>
>>> First, I feel your note is revisiting the topic around the PUA draft [2] in 
>>> a way that runs counter to the earlier formal warning from Yingzhen [1]. 
>>> Reopening that discussion at this point doesn’t help strengthen the UPA 
>>> procedures and seems to be circling back on a topic that the working group 
>>> has already moved past.
>>>
>>> Second, based on the procedures outlined in the UPA draft [3], my 
>>> development team has successfully implemented UPA and is using it as 
>>> foundational part of our BGP PIC FRR solution. We’re quite familiar with 
>>> how link-state protocols operate, and we’ve found the documented behavior 
>>> in [3] to be sufficient for developing an interoperable and reliable 
>>> implementation. In our solution, the UPA is used to trigger BGP PIC fast 
>>> reroute exactly as Peter described [4]. When a UPA is received, the BGP PIC 
>>> FRR process kicks in, and when the UPA is no longer advertised and only the 
>>> summary prefix remains, the system quickly and gracefully reverts back to 
>>> the original state without any issues. This solution is now used by network 
>>> operators who understand the procedures of link-state routing protocols, 
>>> UPA and BGP PIC FRR well.
>>>
>>> [1]
>>> https://mailarchive.ietf.org/arch/msg/lsr/S7Mqk2JljYgG8kjEPmH6KlLtbf
>>> w
>>> /
>>> [2]
>>> https://datatracker.ietf.org/doc/draft-wang-lsr-prefix-unreachable-a
>>> n
>>> n
>>> oucement/ [3]
>>> https://datatracker.ietf.org/doc/draft-ietf-lsr-igp-ureach-prefix-an
>>> n
>>> o
>>> unce/ [4]
>>> https://mailarchive.ietf.org/arch/msg/lsr/EFb71fc-hc-_oMCnksOZfSPt0-
>>> o
>>> /
>>>
>>> Hope this helps clarify our experience and perspective.
>>>
>>> Gunter Van de Velde
>>> (speaking as WG participant)
>>>
>>>
>>>
>>> From: Aijun Wang <[email protected]>
>>> Sent: Tuesday, May 27, 2025 1:05 AM
>>> To: Peter Psenak <[email protected]>
>>> Cc: [email protected]
>>> Subject: [Lsr] Re: 答复: I-D Action:
>>> draft-ietf-lsr-igp-ureach-prefix-announce-06.txt
>>>
>>>
>>> CAUTION: This is an external email. Please be very careful when clicking 
>>> links or opening attachments. See the URL nok.it/ext for additional 
>>> information.
>>>
>>> Hi, Peter:
>>>
>>> Please refrain your comments.
>>> As the initiators of such mechanism, we describe the whole process 3 years 
>>> earlier than the first version of your draft.
>>>
>>> Respect the creator of any idea is the basic behavior of IETF community.
>>>
>>> Back to your example:
>>> You forgot the important part of the puzzle—-the application that the UPA 
>>> triggered.
>>>
>>> How and when the application being triggered back to its original state?
>>>
>>> Image one scenario, some nodes advertised accidentally the wrong UPA 
>>> signals within the network, how can you revoke it quickly and eliminate the 
>>> wrong triggered actions?
>>>
>>>
>>> Aijun Wang
>>> China Telecom
>>>
>>>
>>> On May 26, 2025, at 17:52, Peter Psenak <mailto:[email protected]> wrote:
>>>
>>> On 26/05/2025 10:26, Aijun Wang wrote:
>>> No,  summary can’t achieve the same aim of the “Explicit Withdrawn Signal”, 
>>> for example, switch back to the application’s original state.
>>> you don't understand the basic operation of the protocol.
>>> 1. prefix p1/32 is summarized with p2/16. P1 is reachable via 
>>> summary 2. router that generated p1 went down 3. UPA for p1/32 was 
>>> generated 4. router that generated p1 came back 5. UPA was removed 
>>> and we are back to state (1) Peter
>>>
>>> 发件人: Peter Psenak [mailto:[email protected]]
>>> 发送时间: 2025年5月26日 15:41
>>> 收件人: Aijun Wang mailto:[email protected]
>>> 抄送: mailto:[email protected]
>>> 主题: Re: 答复: [Lsr] Re: 答复: I-D Action:
>>> draft-ietf-lsr-igp-ureach-prefix-announce-06.txt
>>>
>>> On 26/05/2025 03:29, Aijun Wang wrote:
>>> Then one new deficiency for the mechanism is emerging:
>>>
>>> The lack of the Explicit Withdrawn Signal(EWS) when the prefix is reachable 
>>> again.
>>> Please note, stop sending the UPA message doesn’t mean the prefix is 
>>> reachable again.
>>> If there is no EWS, then the network can’t back to its original state 
>>> before the UPA signaling when the reachable of prefix recover.
>>> there is still a summary that covers the prefix reachability.
>>> Peter
>>>
>>>
>>> Best Regards
>>>
>>> Aijun Wang
>>> China Telecom
>>>
>>>
>>>
>>> 发件人: Peter Psenak [mailto:[email protected]]
>>> 发送时间: 2025年5月23日 19:11
>>> 收件人: Aijun Wang mailto:[email protected]
>>> 抄送: mailto:[email protected]
>>> 主题: Re: [Lsr] Re: 答复: I-D Action:
>>> draft-ietf-lsr-igp-ureach-prefix-announce-06.txt
>>>
>>> On 23/05/2025 12:48, Aijun Wang wrote:
>>> Then nothing needs to be standardized when the prefix becomes reachable 
>>> again.
>>>
>>> 1) In some critical scenarios, when the ABR sends one UPA message out and 
>>> the prefix becomes reachable immediately, what the ABR can do is to stop 
>>> advertising UPA.
>>> and that is exactly what the text says.
>>> Peter
>>>
>>>
>>> The sent UPA message will eventually trigger the action on the receiver, 
>>> even the prefix is reachable immediately.
>>>
>>> 2) In normal situations, the ABR sends the UPA message for some time and 
>>> stop sending it further. At this time, when the prefix becomes reachable, 
>>> nothing needs to be done at ABR.
>>>
>>> The receiver will also act on the UPA signaling.
>>>
>>> It’s irrelevant then whether the prefix is reachable or not after the UPA 
>>> signaling is sent out.
>>>
>>>
>>> Aijun Wang
>>> China Telecom
>>>
>>>
>>>
>>>
>>> On May 23, 2025, at 17:18, Peter Psenak mailto:[email protected] wrote:
>>> On 23/05/2025 10:10, Aijun Wang wrote:
>>> Then, what’s the differences between the two statements:
>>> first is for case when the prefix reachability is not regained after UPA 
>>> was generated.
>>> Second is when the prefix reachability was regained before the UPA was 
>>> withdrawn. It basically says UPA must be  withdrawn at the time the prefix 
>>> becomes reachable.
>>>
>>>
>>> “UPA advertisements SHOULD therefore be withdrawn after some amount of 
>>> time, that would provides sufficient time for UPA to be flooded 
>>> network-wide and acted upon by receiving nodes, but limits the presence of 
>>> UPA in the network.”
>>>
>>> And:
>>>
>>> “ABR or ASBR MUST withdraw the previously advertised UPA when the reason 
>>> for which the UPA was generated was lost - e.g. prefix reachability was 
>>> restored or its metric has changed such that it does not represent the 
>>> protocol specific maximum prefix metric.”
>>>
>>> Here, does  “withdraw” just mean to “stop advertisement”?
>>> yes.
>>> Peter
>>>
>>> If no, what’s the mechanism of second “withdraw”?
>>>
>>>
>>> Best Regards
>>>
>>> Aijun Wang
>>> China Telecom
>>>
>>> 发件人: mailto:[email protected]
>>> [mailto:[email protected]] 代表 Peter Psenak
>>> 发送时间: 2025年5月23日 14:55
>>> 收件人: Aijun Wang mailto:[email protected]; 
>>> mailto:[email protected]
>>> 主题: [Lsr] Re: 答复: I-D Action:
>>> draft-ietf-lsr-igp-ureach-prefix-announce-06.txt
>>>
>>> On 23/05/2025 03:32, Aijun Wang wrote:
>>> Hi, All:
>>>
>>> I must point out that the updated draft doesn't address previous issues 
>>> that described in [1].
>>> Especially, the activation of flawed LSInfinity feature(there is detail 
>>> analysis for this flawed feature that is defined in OSPF 2328).
>>>
>>> And, some updated contents will deteriorate the traffic pattern within the 
>>> network.
>>> For example, It says: “ABR or ASBR MUST withdraw the previously advertised 
>>> UPA when the reason for which the UPA was generated was lost”.
>>> The above requirement will advertise the specific prefixes within the 
>>> network, which will weaken the original summary effect, and attract the 
>>> traffic via one or some of ABRs.
>>> no, above is not true, the new text does not say to advertise reachablity 
>>> for a summarized prefix, it only talks about removing the previously 
>>> advertised UPA.
>>> Please read carefully before commenting.
>>> Peter
>>>
>>>
>>> [1]: Reasons of abandoning UPA:
>>> https://datatracker.ietf.org/doc/draft-wang-lsr-reasons-of-abandon-u
>>> p
>>> a
>>> -proposal/
>>>
>>>
>>> Best Regards
>>>
>>> Aijun Wang
>>> China Telecom
>>>
>>>
>>>
>>>
>>>
>>> -----邮件原件-----
>>> 发件人: mailto:[email protected]
>>> [mailto:[email protected]] 代表
>>> mailto:[email protected]
>>> 发送时间: 2025年5月22日 21:20
>>> 收件人: mailto:[email protected]
>>> 抄送: mailto:[email protected]
>>> 主题: [Lsr] I-D Action:
>>> draft-ietf-lsr-igp-ureach-prefix-announce-06.txt
>>>
>>> Internet-Draft draft-ietf-lsr-igp-ureach-prefix-announce-06.txt is now 
>>> available. It is a work item of the Link State Routing (LSR) WG of the IETF.
>>>
>>>       Title:   IGP Unreachable Prefix Announcement
>>>       Authors: Peter Psenak
>>>                Clarence Filsfils
>>>                Daniel Voyer
>>>                Shraddha Hegde
>>>                Gyan Mishra
>>>       Name:    draft-ietf-lsr-igp-ureach-prefix-announce-06.txt
>>>       Pages:   14
>>>       Dates:   2025-05-22
>>>
>>> Abstract:
>>>
>>>       In the presence of summarization, there is a need to signal loss of
>>>       reachability to an individual prefix covered by the summary.  This
>>>       enables fast convergence by steering traffic away from the node which
>>>       owns the prefix and is no longer reachable.
>>>
>>>       This document describes how to use the existing protocol mechanisms
>>>       in IS-IS and OSPF, together with the two new flags, to advertise such
>>>       prefix reachability loss.
>>>
>>> The IETF datatracker status page for this Internet-Draft is:
>>> https://datatracker.ietf.org/doc/draft-ietf-lsr-igp-ureach-prefix-an
>>> n
>>> o
>>> unce/
>>>
>>> There is also an HTMLized version available at:
>>> https://datatracker.ietf.org/doc/html/draft-ietf-lsr-igp-ureach-pref
>>> i
>>> x
>>> -announce-06
>>>
>>> A diff from the previous version is available at:
>>> https://author-tools.ietf.org/iddiff?url2=draft-ietf-lsr-igp-ureach-
>>> p
>>> r
>>> efix-announce-06
>>>
>>> Internet-Drafts are also available by rsync at:
>>> rsync.ietf.org::internet-drafts
>>>
>>>
>>> _______________________________________________
>>> Lsr mailing list -- mailto:[email protected] To unsubscribe send an email 
>>> to mailto:[email protected]
>>>
>>>
>>> _______________________________________________
>>> Lsr mailing list -- mailto:[email protected] To unsubscribe send an email 
>>> to mailto:[email protected]
>>>
>>>
>>>
>>> _______________________________________________
>>> Lsr mailing list -- mailto:[email protected] To unsubscribe send an email 
>>> to mailto:[email protected]
>>>
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