Re: [trill] Mirja Kühlewind's No Objection on draft-ietf-trill-irb-13: (with COMMENT)

Donald Eastlake <> Thu, 30 June 2016 01:49 UTC

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From: Donald Eastlake <>
Date: Wed, 29 Jun 2016 21:49:32 -0400
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To: Mirja Kuehlewind <>
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Subject: Re: [trill] =?utf-8?q?Mirja_K=C3=BChlewind=27s_No_Objection_on_draft-?= =?utf-8?q?ietf-trill-irb-13=3A_=28with_COMMENT=29?=
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Hi Mirja,

Thanks for your comments. See below.

On Wed, Jun 29, 2016 at 6:13 PM, Mirja Kuehlewind <> wrote:
> Mirja Kühlewind has entered the following ballot position for
> draft-ietf-trill-irb-13: No Objection
> ...
> ----------------------------------------------------------------------
> ----------------------------------------------------------------------
> Two minor comments:
> 1) There are only a few SHOULDs and MUSTs in this whole document
>    and where they are used it is often not very clear what the action
>    is that should follow and how it should be implemented
>   (e.g. "The network operator MUST ensure the consistency of the
>    tenant ID on each edge RBridge for each routing domain.").
>   And maybe there are actually more case where normative
>   language should be used?
>   Please double-check the use of normative language in this document!


>  2) A similar question on the following part:
>   „If a tenant is deleted on an edge RBridge RB1, RB1 SHOULD re-
>    advertise the local tenant Data Label, tenant gateway MAC, and
>    related IP prefixes information of the rest tenants to other edge
>    RBridges. […] Therefore the transient routes consistency won't
>   cause issues other than wasting some network bandwidth.“
>   Wasting network resources actually can be an issue.
>   So why is this not an MUST?

Wasting bandwidth can be an issue but is not necessarily an issue,
particularly if it occurs only during a brief transient period. TRILL
does not make it mandatory to implement with the maximum link
utilization efficiency. For example, TRILL multi-destination traffic
is send over a distribution tree. If there are no devices interested
in traffic in a particular VLAN further down a branch of the tree, it
is recommended that traffic heading down that branch be pruned. But
this is not mandatory. The TRILL campus will operate "correctly"
without such pruning and if someone wants to make a very simple, low
end implementation without pruning, so be it. (As far as I know, all
existing TRILL implementation do prune distribution trees.)

 Donald E. Eastlake 3rd   +1-508-333-2270 (cell)
 155 Beaver Street, Milford, MA 01757 USA