Re: [Bier] WG adoption call for draft-chen-bier-frr-02

Michael Menth <menth@uni-tuebingen.de> Tue, 16 March 2021 11:11 UTC

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From: Michael Menth <menth@uni-tuebingen.de>
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Subject: Re: [Bier] WG adoption call for draft-chen-bier-frr-02
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Hi Tony, all,

Am 16.03.2021 um 11:08 schrieb Tony Przygienda:

> I think it's a good addition within the architecture for the case IGP is
> not used for signalling, e.g. when controller or static programming.

Right. The solution may make sense if the routing underlay does not
offer FRR capabilities.

> 
> The draft must however explain in what scenarios it is used and quote
> the according IGP drafts to guarantee loop-free behavior (well, BIER
> will tie-break loops but we'll have 1x microloop & possibly not deliver
> payload if BIER FRR is not properly computed/intsalled). With that the
> draft should also pay attention to how the function is deployed/updated
> network-wide if IGP is not present

I agree. in the absence of an IGP, the "native BIER-FRR on bier layer"
must be set by a controller.

So, below the line, an applicability statement would be helpful. What
are those cases?
- IGP running but without FRR on the routing underlay?
- No IGP and no FRR on the routing underlay?

However, if the controller takes care of BIER-FRR, what could be reasons
for missing FRR on the routing underlay? If there is a FRR on the
routing underlay (also provided through a controller), tunnel-based
bier-frr solves the problem in a transparent way.

BTW, we studied protection variants for controller-based infrastructures
(for routing underlays, not for BIER). Challenge is to keep state low.
LFA-based solutions help a lot and outperform others. 100% protection is
possible with only little additions. Results are available:
https://atlas.informatik.uni-tuebingen.de/~menth/papers/Menth20-Sub-6.pdf (under
revision)

Regards,

Michael

> 
> thanks
> 
> -- tony
> 
> On Tue, Mar 16, 2021 at 7:41 AM <zhang.zheng@zte.com.cn
> <mailto:zhang.zheng@zte.com.cn>> wrote:
> 
>     A 2-week WG adoption call begins for the following draft:
> 
>     https://datatracker.ietf.org/doc/draft-chen-bier-frr/
>     <https://datatracker.ietf.org/doc/draft-chen-bier-frr/>
> 
>     Please indicate your support or objection by March 30th, 2021.
> 
>     Authors, please respond to the list indicating whether you are aware
>     of any IPR that applies to this draft.
> 
>     Thanks,
> 
>     Sandy (As WG secretary, on behalf of Greg/Tony)
> 
> 
> 
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-- 
Prof. Dr. habil. Michael Menth
University of Tuebingen
Faculty of Science
Department of Computer Science
Chair of Communication Networks
Sand 13, 72076 Tuebingen, Germany
phone: (+49)-7071/29-70505
fax: (+49)-7071/29-5220
mailto:menth@uni-tuebingen.de
http://kn.inf.uni-tuebingen.de