Re: [Lsr] WG Adoption Call-draft-gong-lsr-ospf-unreachable-link(02/23/24 - 03/08/24)

["Les Ginsberg (ginsberg)" <[e-mail]>]

Or – if the authors want to consider my comments – replace “unreachable” in the name with something more apt – perhaps:

“lsr-ospf-max-link-metric”

😊

   Les


From: Lsr <[e-mail]> On Behalf Of Yingzhen Qu
Sent: Tuesday, March 12, 2024 1:11 PM
To: Liyan Gong <[e-mail]>
Cc: [e-mail]; Acee Lindem <[e-mail]>; Gyan Mishra <[e-mail]>; lsr <[e-mail]>; lsr-chairs <[e-mail]>; ketan Talaulikar <[e-mail]>
Subject: Re: [Lsr] WG Adoption Call-draft-gong-lsr-ospf-unreachable-link(02/23/24 - 03/08/24)

Hi all,

The adoption call has ended.

There is strong consensus, and all the authors and contributors have replied to the IPR call thread, so this draft is now adopted.

Authors, please upload a WG version with name draft-ietf-lsr-ospf-unreachable-link when the datatracker is open.

Please continue the discussion to further refine the draft.

Thanks,
Yingzhen

On Mon, Mar 11, 2024 at 7:34 PM Liyan Gong <[e-mail]<mailto:[e-mail]>> wrote:

Hi Jie,



Thank you for your replies. Please see inline with [Liyan].



Best Regards,

Liyan




----邮件原文----
发件人："Dongjie \\(Jimmy\\)<file://(Jimmy/)>" <jie.dong=[e-mail]<mailto:[e-mail]>>
收件人：Acee Lindem  <[e-mail]<mailto:[e-mail]>>,Liyan Gong  <[e-mail]<mailto:[e-mail]>>
抄　送: Gyan Mishra  <[e-mail]<mailto:[e-mail]>>,Yingzhen Qu <[e-mail]<mailto:[e-mail]>>,lsr  <[e-mail]<mailto:[e-mail]>>,lsr-chairs <[e-mail]<mailto:[e-mail]>>,ketan Talaulikar  <[e-mail]<mailto:[e-mail]>>
发送时间：2024-03-11 23:11:49
主题：Re: [Lsr] WG Adoption Call-draft-gong-lsr-ospf-unreachable-link(02/23/24 - 03/08/24)


Hi Acee and Liyan,

Please see some replies inline with [Jie] :

From: Acee Lindem [mailto:[e-mail]]
Sent: Sunday, March 10, 2024 5:37 AM
To: Liyan Gong <[e-mail]<mailto:[e-mail]>>
Cc: Gyan Mishra <[e-mail]<mailto:[e-mail]>>;  Dongjie (Jimmy) <[e-mail]<mailto:[e-mail]>>;  Yingzhen Qu <[e-mail]<mailto:[e-mail]>>;  lsr <[e-mail]<mailto:[e-mail]>>; lsr-chairs <[e-mail]<mailto:[e-mail]>>;  ketan Talaulikar <[e-mail]<mailto:[e-mail]>>
Subject: Re: [Lsr] WG Adoption Call -draft-gong-lsr-ospf-unreachable-link(02/23/24 - 03/08/24)

All,

With respect to the naming of the OSPF constants, I think we should go with:

     LSLinkInfinity                    - 0xffff
     MaxReachableLinkMetric - 0xfffe

LSLinkInfinity is analogous to LSInfinity.

[Jie]  This is OK to me.



See inline.



On Mar 2, 2024, at 06:16, Liyan Gong <[e-mail]<mailto:[e-mail]>> wrote:


Hi Gyan and Jie,

I am not entirely sure if the suggestions from Ketan in previous email can address these two concerns. If not fully addressed, please feel free to let us know.

Overall, this feature is applicable to all FAs, including FA0. The next version will further elaborate on the relationships between new features and FAs, as well as optimize the use-case descriptions and corresponding name to reflect "Unreachable"  in a way that is easier to understand.

Appreciate everyone's discussion. It is very helpful.


[Jie] Thanks, this aligns with my understanding: it applies to all SPF  computations (including Flexible Algorithms) which make use of IGP metric. And it would be good to replace unreachable with some more accurate description.



[Liyan]Thanks.I am also considering this matter and hope to get your advice. Would it be better to use "Infinity Link" instead of " Unreachable Link" for both the content and the title of the draft?



Best Regards,

Liyan




----邮件原文----
发件人：Gyan Mishra  <[e-mail]<mailto:[e-mail]>>
收件人："Dongjie (Jimmy)" <jie.dong=[e-mail]<mailto:jie.dong=[e-mail]>>
抄　送: Yingzhen Qu  <[e-mail]<mailto:[e-mail]>>,lsr  <[e-mail]<mailto:[e-mail]>>,lsr-chairs  <[e-mail]<mailto:[e-mail]>>
发送时间：2024-03-01 11:27:32
主题：Re: [Lsr] WG Adoption Call - draft-gong-lsr-ospf-unreachable-link(02/23/24 - 03/08/24)
Hi Jie

Some answers in-line

On Thu, Feb 29, 2024 at 2:31 AM Dongjie (Jimmy) <jie.dong=[e-mail]<mailto:[e-mail]>> wrote:
Hi Yingzhen,

I’ve read the latest version of this document and support its adoption.  It is a useful  feature in general to exclude some of the links from SPF  computation.

I also have some comments for the authors to consider, they can be solved after the adoption.


1.       I’m not sure the purpose is to advertise an unreachable link in OSPF, from the use cases in the draft, the link is still reachable and  can be used for some services,  just it needs be excluded from normal SPF calculation. If this is correct, it is better the title of the draft and the name of the new capability Flag need to be updated to reflect this.

LSLinkInfinity would always indicate the link is unreachable. However, there is no real need to advertise it for other services since in these cases the advertisement is optional.

[Jie] IMO once LSLinkInfinity is advertised for a link, it would impact all services which  rely on SPF computation based on IGP metric.  Regarding “for other services the advertisement is optional”, do you mean other services would rely on metric-types other than IGP metric? This is true for services which use TE paths, while there maybe issue with  Flex Algorithm (as discussed below).



 Gyan> I agree with you and that is as well stated in the draft that MaxLinkMetric (0xFFFF) does not exclude the link from SPF and thus  requires RI LSA with capability bit set for MaxLinkMetric (0xFFFF) for link to be excluded from SPF. Maybe “OSPF RI Capability LSA”.

I think the capability should be LSLinkInfinity support.

[Jie] This is OK.



2.       In the Flex-Algo use case, if the metric of a link is set to MaxLinkMetric (0xFFFF) to exclude it from normal SPF computation, while a  Flex-Algo is defined to  use the same metric type for path calculation, will it cause the link also be excluded from the Flex-Algo path computation? If not, will metric value 0xFFFF be used in the Flex-Algo computation? In other word, the interaction between  this new feature and  Flex-Algo needs to be further elaborated.
    Gyan>  I agree that the RI LSA capability flag for MaxLinkMetric (0xFFFF) is applicable  to base Algo 0 and any Algo.  However AFAIK you would have to explicitly set the RI flag the particular Algo.  The use case described in this draft is when you are using flex algo for network slicing meaning you have both algo 0 and 128 on the same links and  not a separate sub topology and in that case in order to avoid best effort traffic from going over the same link used for algo 128  you would need to use this RI capability flag.  This concept we have talked about comes into play of degree of network slicing  and isolation to meet SLO SLE  requirements.

LSLinkInfinity would exclude the link from a flex algorithm as well. However, the correct way to exclude it by omitting the advertisement.

[Jie] Agree that if a Flex Algorithm uses IGP metric as its metric type, LSLinkInfinity  would impact the Flex-Algo computation as well. While a Flex-Algo which uses other metric-types would not be impacted. Is that what you mean by “omitting the advertisement”?

[Liyan]Yes, I think both of you have the same ideas which alligns with the draft. If misunderstanding, please Acee correct me.

Best regards,
Jie


Thanks,
Acee



Best regards,
Jie

From:  Lsr [mailto:[e-mail]<mailto:[e-mail]>] On Behalf Of Yingzhen Qu
Sent: Friday, February 23, 2024 1:28 PM
To: lsr <[e-mail]<mailto:[e-mail]>>;  lsr-chairs <[e-mail]<mailto:[e-mail]>>
Subject: [Lsr] WG Adoption Call - draft-gong-lsr-ospf-unreachable-link (02/23/24 - 03/08/24)


Hi,



This email begins a 2 week WG adoption poll for the following draft:

https://datatracker.ietf.org/doc/draft-gong-lsr-ospf-unreachable-link/



Please review the document and indicate your support or objections by March 8th, 2024.

Authors and contributors, please respond to the list indicating whether you are aware of any IPR that applies to the draft.

Thanks,

Yingzhen
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Gyan Mishra
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