Re: [Isis-wg] ISIS SR Flexible Algorithm (Resending with alias correction)

Peter Psenak <ppsenak@cisco.com> Mon, 20 November 2017 22:30 UTC

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Date: Mon, 20 Nov 2017 23:30:51 +0100
From: Peter Psenak <ppsenak@cisco.com>
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To: Tony Przygienda <tonysietf@gmail.com>, "Acee Lindem (acee)" <acee@cisco.com>
CC: "isis-wg@ietf.org" <isis-wg@ietf.org>, "draft-hegdeppsenak-isis-sr-flex-algo@ietf.org" <draft-hegdeppsenak-isis-sr-flex-algo@ietf.org>
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Subject: Re: [Isis-wg] ISIS SR Flexible Algorithm (Resending with alias correction)
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Hi Tony,

On 20/11/17 22:11 , Tony Przygienda wrote:
> So, it seems that there will be a new draft with 242 covering all
> algorithms (i.e. no MT specific algo advertisement anymore).

there is no MT specific algo advertisement in the current flex-algo 
draft. MTs are independent to flex-algos.

>
> Then I thought each MT advertises which Flex it supports. Is the
> assumption that you can run multiple algorithms per MT? How would you
> otherwise have a two-algorithms-to-same-prefix problem?
>
> Is there some kind of conceptual model of FlexAlgo, i.e. how many of
> what associated with how  many of the other (MT to algo, algo to
> protocol instance etc) ...

There is many to many relationship between MT and Flex-Algo. Single MT 
can use many Flex-Algos and single Flex-Algo can be used on many MTs.

thanks,
Peter

>
> -- tony
>
> On Mon, Nov 20, 2017 at 10:19 AM, Acee Lindem (acee) <acee@cisco.com
> <mailto:acee@cisco.com>> wrote:
>
>     Hi Shraddha, Peter, et al,
>
>     The comment on the draft I had was that the conflict case where two
>     ISIS routers advertise the same multi-homed prefix with a different
>     algorithm needs to be covered. I wouldn’t try and optimize for this
>     and would just do whatever is simplest but avoids loops (e.g., log
>     the situation and prefer the path computed with the lowest numbered
>     algorithm).
>
>     Thanks,
>     Acee
>
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