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Re: [Lsr] Prefix Unreachable Announcement Use Cases

Jeff Tantsura <jefftant.ietf@gmail.com> Mon, 16 November 2020 10:35 UTC

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From: Jeff Tantsura <jefftant.ietf@gmail.com>
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Date: Mon, 16 Nov 2020 02:35:48 -0800
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Cc: Aijun Wang <wangaijun@tsinghua.org.cn>, lsr <lsr@ietf.org>, "Acee Lindem (acee)" <acee=40cisco.com@dmarc.ietf.org>
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To: Robert Raszuk <robert@raszuk.net>
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Subject: Re: [Lsr] Prefix Unreachable Announcement Use Cases
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+1 with Robert.

So you expect the following RIB state after PUA has been advertised:
10.0.0.1 - drop
10/24 - forward 

Unless there’s a recursively discarded next-hop (ala RTBH )  - how do you envision it?

Regards,
Jeff

> On Nov 16, 2020, at 00:25, Robert Raszuk <robert@raszuk.net> wrote:
> 
> 
>> I was not bringing RIFT's negative routies example as something inherently negative. I was just pointing it out to illustrate that today's data plane lookup does not really support "if does not match" checks.
>> 
>> [WAJ] In data plane, the device do still the “match” check, not “does not match” check.  When the router receives the PUA information, it will install one black hole route for a short time.
>> 
> 
> So your idea is that you install route for unreachable prefix to /dev/null ? 
> 
> And how would that help connectivity restoration ? 
> 
> Moreover it seems that it will just also prevent any local protection to locally bypass the failed destination. 
> 
> Bottom line is that I agree with one problem statement. However IMHO described actions upon reception of PUA are questionable at best. 
> 
> Cheers,
> R.

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