[bess] Re: [**EXTERNAL**] Inverse multi-layer OAM

["Shah, Himanshu" <[e-mail]>]

Some edits on the below (that was sent from phone).
Also combining the thread since the question was posted on bess as well spring wg list.

Thanks,
Himanshu


From: Shah, Himanshu <[e-mail]>
Date: Wednesday, March 19, 2025 at 12:40 PM
To: Greg Mirsky <[e-mail]>, spring <[e-mail]>
Cc: [e-mail] <[e-mail]>
Subject: Re: [**EXTERNAL**] Inverse multi-layer OAM
Thanks for the comments Greg.
You did understand the point correctly.
We recommend that for the purpose of networks that want to take advantage of Eligibility mechanism for intent verification especially for fault detection scheme, the e2e fault detection Timers are kept more aggressive than local link fault detection timers.
This is a better choice than turning off TI-LFA at each node.
For example - 1hop timers at 10 ms interval with 3 miss and s-bfd at 5ms interval or 10ms with 2 miss. This is just an example.
It’s a choice, if one wants e2e protection to take higher precedence over local protection. As I mentioned, this behavior is more preferable to transport centric service providers that we have talked to.

Thanks,
Himanshu

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________________________________
From: Greg Mirsky <[e-mail]>
Sent: Wednesday, March 19, 2025 11:05:13 AM
To: Shah, Himanshu <[e-mail]>; spring <[e-mail]>
Cc: [e-mail] <[e-mail]>
Subject: [**EXTERNAL**] Inverse multi-layer OAM



Hi Himanshu,

Thank you for the presentation of draft-karboubi-spring-sidlist-optimized-cs-sr [datatracker.ietf.org]<https://urldefense.com/v3/__https:/datatracker.ietf.org/doc/draft-karboubi-spring-sidlist-optimized-cs-sr/__;!!OSsGDw!K8rPlFfq1tAkxUuApqsa6NVHHTDMA2QDx9rnvs1ifRr3zoV5C_wdO2WyBH2vmRn0i0E8ovq-lHE5WPqh$>. If I understood your response to Ali correctly, the proposed mechanism is expected to use more aggressive network failure detection than the link layer. If that is correct, I have several questions about the multi-layer OAM:

  *   AFAIK link-layer failures are detected within 10 ms using a connectivity check mechanism (CCM of Y.1731 or a single-hop BFD) with a 3.3 ms interval.
  *   If the link failure is detectable within 10 ms, what detection time for the path, i.e., E2E connection failure detection, is suggested? What interval between test probes will be used in that case?
  *   Furthermore, even if the path converges around the link failure before the local protection is deployed, the link failure will be detected, and the protection mechanism will be deployed despite the Orchestrator setting up its recovery path in the network. If that is correct, local defect detection and protection are unnecessary overheads. Would you agree?



Regards,

Greg