Re: [Lsr] Concerns with draft-chunduri-lsr-isis-preferred-path-routing

"Les Ginsberg (ginsberg)" <ginsberg@cisco.com> Tue, 17 July 2018 17:37 UTC

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From: "Les Ginsberg (ginsberg)" <ginsberg@cisco.com>
To: Uma Chunduri <uma.chunduri@huawei.com>, "Peter Psenak (ppsenak)" <ppsenak@cisco.com>, "Ketan Talaulikar (ketant)" <ketant@cisco.com>, "lsr@ietf.org" <lsr@ietf.org>
CC: "spring@ietf.org" <spring@ietf.org>
Thread-Topic: [Lsr] Concerns with draft-chunduri-lsr-isis-preferred-path-routing
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Date: Tue, 17 Jul 2018 17:37:27 +0000
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Subject: Re: [Lsr] Concerns with draft-chunduri-lsr-isis-preferred-path-routing
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Uma -

I share the concerns expressed by Ketan and Peter.

Although I will certainly consider the additional response you seem to have hinted at in your reply to Peter, it seems to me that Section 6 of your draft acknowledges that there is a scaling problem - and then references what seems to be a non-existent draft (I could not find "draft-ce-ppr-graph-00" ???) as a proposed solution.

In any further response you make it would be good if you did indicate whether you agree PPR has a scaling issue - and given the contents of Section 6 of your draft - also discuss why we should consider PPR + some additional scaling enhancements when we already have at least one solution which does scale linearly.

Thanx.

    Les


> -----Original Message-----
> From: Lsr <lsr-bounces@ietf.org> On Behalf Of Uma Chunduri
> Sent: Tuesday, July 17, 2018 6:43 AM
> To: Peter Psenak (ppsenak) <ppsenak@cisco.com>om>; Ketan Talaulikar (ketant)
> <ketant@cisco.com>om>; lsr@ietf.org
> Cc: spring@ietf.org
> Subject: Re: [Lsr] Concerns with draft-chunduri-lsr-isis-preferred-path-routing
> 
> Hi Peter,
> 
> 
> -----Original Message-----
> From: Peter Psenak [mailto:ppsenak@cisco.com]
> Sent: Tuesday, July 17, 2018 9:34 AM
> To: Uma Chunduri <uma.chunduri@huawei.com>om>; Ketan Talaulikar (ketant)
> <ketant@cisco.com>om>; lsr@ietf.org
> Cc: spring@ietf.org
> Subject: Re: [Lsr] Concerns with draft-chunduri-lsr-isis-preferred-path-routing
> 
> 
> 	> flex-algo is NOT a per path state. It's a regular prefix-SID, which is
> bound to a prefix only.
> 
> Not quite. I will come back to this bit later.
> 
> 	>The problem with your proposal is that you flood all paths to all routers
> in the area and ask every router to evaluate all of them and see which of them
> may apply. This scale poorly.
> 
> Please see Section 6, in 01 version.
> 
> --
> Uma C.
> 
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