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

From: "Mirja Kuehlewind" <[email-masked]>
Date: Wed, 29 Jun 2016 15:13:11 -0700

Mirja Kühlewind has entered the following ballot position for
draft-ietf-trill-irb-13: No Objection

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COMMENT:
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Two minor comments:

1) There are only 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 langauge 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?

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From: Donald Eastlake <[email-masked]>
Date: Wed, 29 Jun 2016 21:49:32 -0400

Hi Mirja,

Thanks for your comments. See below.

On Wed, Jun 29, 2016 at 6:13 PM, Mirja Kuehlewind <[email-masked]> wrote:
> ...
> 1) There are only a few SHOULDs and MUSTs in this whole document
>   Please double-check the use of normative language in this document!

OK.

>   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.)

Thanks,
Donald
===============================
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