[spring] Re: Ask SPRING WG for review draft-liu-spring-sr-policy-flexible-path-selection

Joel Halpern <jmh@joelhalpern.com> Mon, 09 December 2024 03:46 UTC

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Date: Sun, 08 Dec 2024 22:45:47 -0500
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To: Yisong Liu <liuyisong@chinamobile.com>, spring <spring@ietf.org>
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Subject: [spring] Re: Ask SPRING WG for review draft-liu-spring-sr-policy-flexible-path-selection
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Looking at this draft, there seem to be two related aspects, one of 
which makes sense, and one of which needs work.

As a participant, I can understand the general goal.  And adjusting the 
path selection when component link issues reduce the overall available 
bandwidth, increase the end-to-end delay, or increase the expected 
jitter is understandable.  I leave whether this is the right approach to 
that problem to those who have worked more closely with SR policies.

However, if I read section 4.1 properly, it wants to change the path 
selection in response to observed parameters such as observed packet 
loss (frequently in practice caused by congestion.)  On fortunately, 
distributed dynamic path selection based on parameters that are 
sensitive to traffic load has well-known problems with various 
responders adjusting resulting in simply moving the problem.  If you 
have recognized this problem and I missed it, please cite RFC 2386 early 
in the document, and point to the resolution.  If you have not addressed 
this problem, please either do so or restrict the applicability of this 
proposal. Delaying response is not sufficient.

Yours,

Joel

On 12/8/2024 9:37 PM, Yisong Liu wrote:
> Dear WG members,
>
>
> With the rise of AI models, new intelligent computing services require 
> enhanced network reliability, especially in quality-sensitive 
> scenarios like storage-compute separation and real-time inference. The 
> draft-liu-spring-sr-policy-flexible-path-selection offers flexible 
> path switching for quality degradation, crucial for maintaining 
> network performance.
>
> This draft proposed a new mechanism to specify multiple candidate 
> paths for SR policies, allowing for more sophisticated traffic 
> engineering. Itsupports dynamic path adjustments based on real-time 
> network conditions, optimizing resource utilization and ensuring high 
> service quality. This draft aims to provide network operators with 
> greater flexibility and control over traffic routing in SR networks.
>
>
> We have just posted a new version. Please see the draft in the 
> following link:
>
> https://datatracker.ietf.org/doc/draft-liu-spring-sr-policy-flexible-path-selection/
>
>
> I hope you can review this draft and share your feedback. Welcome any 
> questions and comments.
>
> Best Regards
> Yisong on behalf of co-authors
>
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