Re: [spring] [bess] New draft "draft-hr-spring-intentaware-routing-using-color"

["Dhananjaya Rao (dhrao)" <[e-mail]>]

Hi Igor,

Thank you for the quick review. Please see inline (DR##)

From: BESS <[e-mail]> on behalf of Igor Malyushkin <[e-mail]>
Date: Sunday, July 17, 2022 at 2:50 AM
To: "Dhananjaya Rao (dhrao)" <dhrao=[e-mail]>
Cc: "[e-mail]" <[e-mail]>
Subject: Re: [bess] New draft "draft-hr-spring-intentaware-routing-using-color"

Accidently unicasted the previous message to Dhananjaya, replying to the group.

Hello Dhananjaya,

Can you please clarify some moments in Section 6.2? First, I don't see any sign of Section 5.1.9 (also referred to in Section 6.3.1.7) in the document. Looks like missed.

DR ## Thanks; yes, it was a reference to Section 5.9. Missed updating during conversion. Will be fixed in next revision.

I'm interested in the next scenario. Let's suppose that for a service instance (VPN or a global table) there are two ingress flows per single destination. This destination is color-marked and resolved by an intent-aware underlay. Also, there is a best-effort path as a fallback. Using per-flow steering that is based on 5-tuple IP flow is it possible to send ingress traffic from a source S1 via the intent-aware path, and ingress traffic from a source S2 via a fallback (best-effort) path at the same time? My reading of Section 6.2 shows me that it's not possible. But I strongly believe that there are cases when an intent/colored path for a distinct destination must be used only by the subset of members of service, and the same destination must be available for the rest members of the service via a best-effort path(s) only. I can show some business logic behind this if you will.

DR## Sending one IP flow for a destination via an intent-aware path while sending another flow for the same destination via a best-effort path (or a different intent-aware path) is a valid use-case, which is intended to be covered. It was described more explicitly in  https://datatracker.ietf.org/doc/draft-dskc-bess-bgp-car-problem-statement/  Section 1.2.11, but reduced in the merged doc. We can make it more explicit.

In fact, this scenario is already supported by existing intent-aware solutions such as SR-TE :

https://datatracker.ietf.org/doc/html/draft-ietf-spring-segment-routing-policy-22#section-8.6

Regards,
-Dhananjaya


Hope it helps, and thank you!

сб, 16 июл. 2022 г. в 07:15, Dhananjaya Rao (dhrao) <dhrao=[e-mail]<mailto:[e-mail]>>:

Hello BESS folks,

The co-authors of https://datatracker.ietf.org/doc/draft-dskc-bess-bgp-car-problem-statement/ and https://datatracker.ietf.org/doc/draft-hegde-spring-mpls-seamless-sr/ have published a merged problem statement document :

https://datatracker.ietf.org/doc/draft-hr-spring-intentaware-routing-using-color/

We request working group to review and provide your inputs.

Regards,
-Dhananjaya (for the co-authors)


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