Subject: [Idr] Mirja Kühlewind's No Objection on draft-ietf-idr-add-paths-14: (with COMMENT)

From: "Mirja Kuehlewind" <[email-masked]>
Date: Mon, 02 May 2016 02:35:59 -0700

Mirja Kühlewind has entered the following ballot position for
draft-ietf-idr-add-paths-14: No Objection

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COMMENT:
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Two quick comments:

1) Section 6 says: „The applications are detailed in separate documents.“
Does this doc already exists? A reference would be good!

2) One clarification question: When a path with a new identifier is
advertised this actually does not mean that these two paths are
different, right? Some one could advertise the same path twice with
different identifiers, right? Should this be explicitly mention
somewhere?

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From: "Alvaro Retana (aretana)" <[email-masked]>
Date: Tue, 3 May 2016 14:45:13 +0000

On 5/2/16, 5:35 AM, "Mirja Kuehlewind" <[email-masked]> wrote:

[Author hat on.]

Mirja:

Hi!

>different identifiers, right? Should this be explicitly mention

Right, the two (or more paths) don't have to be different.  I don't think
we need to specifically call the general case out as there is no issue
related to path selection when that is done.

OTOH, we do mention one instance of advertising "the same" path where
there might be a need to differentiate -- take a look at the last
paragraph in Section 6.

Thanks!

Alvaro.

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From: "Mirja Kuehlewind (IETF)" <[email-masked]>
Date: Tue, 3 May 2016 18:19:00 +0200

Hi Alvaro,

okay, that’s fine. I was think about a case, where two paths are advertised and than maybe someones uses those two paths to do some complex multipath routing, while at the end this would be unnecessary as both advertised path are physically the same. Not sure if that would ever be the case or I’m making things up. If you tell me that there is no further discussion needed, that’s fine for me as the doc doesn’t really talk at all about any assumptions that should be made about the (physical) path that is used.

Mirja

> Am 03.05.2016 um 16:45 schrieb Alvaro Retana (aretana) <[email-masked]>:
>

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From: "Alvaro Retana (aretana)" <[email-masked]>
Date: Wed, 4 May 2016 19:58:44 +0000

On 5/3/16, 12:19 PM, "Mirja Kuehlewind (IETF)" <[email-masked]> wrote:

Mirja:

Hi!

>I was think about a case, where two paths are advertised and than maybe
>someones uses those two paths to do some complex multipath routing, while
>at the end this would be unnecessary as both advertised path are
>physically the same. Not sure if that would ever be the case or I¹m
>making things up. 

Not really.  In general, for any type of complex multi-path routing we
would probably rely on the IGP information which provides a better picture
of the path inside the network.  BGP only points at the next-hop, which in
this case is the next autonomous system (and not necessarily something
directly connected).

Having said that, BGP does provide an AS-PATH, but that only shows a high
level (logical) view of the path being used.  From that point of view it
would be easy to determine whether the routes would follow the same
path...but not with physical granularity.

>If you tell me that there is no further discussion needed, that¹s fine
>for me as the doc doesn¹t really talk at all about any assumptions that
>should be made about the (physical) path that is used.

No assumptions should be made -- the document only changes the
interpretation of the NLRI, not the selection process of the best route.

Thanks!

Alvaro.