Re: [Lsr] Prefix Unreachable Announcement Use Cases

Robert Raszuk <> Fri, 20 November 2020 20:45 UTC

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From: Robert Raszuk <>
Date: Fri, 20 Nov 2020 21:45:12 +0100
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To: Tony Przygienda <>
Cc: Aijun Wang <>, lsr <>, Jeff Tantsura <>, "Acee Lindem (acee)" <>
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Subject: Re: [Lsr] Prefix Unreachable Announcement Use Cases
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Hey Tony,

>  people somehow implying a map of RIFT negative disaggregation in
relation to this work

I think those people just made a subtle point that considering IGP alone if
you want to influence your data plane forwarding by advertising PUA in
today's hardware you really need to install more specific blocks of the
summary routes which PUA punched the hole in as sent by say one of the
ABR's. Analogy made to RIFT was just limited to this data plane fragment

And that comment was not to compare PUA to RIFT negative routing in any
way. It was just to a) realize what could be required if such a use case
continues and more importantly b) highlight that if we just use PUA in the
control plane to for example invalidate BGP next hops or other overlay
service routes the disaggregation piece does not apply.


On Fri, Nov 20, 2020 at 9:09 PM Tony Przygienda <> wrote:

> On Fri, Nov 20, 2020 at 6:27 AM Aijun Wang <>
> wrote:
>> Hi, Tony:
>> Aijun Wang
>> China Telecom
>> On Nov 20, 2020, at 17:45, Tony Przygienda <> wrote:
>> Yes, acknowledging the idea of negative disaggregation is inspired by
>> RIFT work is fine (and normally, when inspired by an idea at least in
>> research cycles it is considered basic courtesy to refer to the according
>> source, something has been lost more and more in IETF over time I dare to
>> observe which in itself reflects on the community IMO) but please do not
>> try to compare the two beyond that.
>> [WAJ] PUA has no relation with RIFT. I have not yet study what’s problem
>> it encountered, but welcome the experts have such design experience to
>> point out the pitfall that PUA can bypass.
> aha, ok, I just chimed in because I saw people somehow implying a map of
> RIFT negative disaggregation in relation to this work but if this is a
> completely different mechanism than I just watch from the sidelines
> thanks
> -- tony