Subject: [trill] Alvaro Retana's Discuss on draft-ietf-trill-smart-endnodes-10: (with DISCUSS)

From: Alvaro Retana <[email-masked]>
Date: Mon, 05 Mar 2018 13:34:26 -0800

Alvaro Retana has entered the following ballot position for
draft-ietf-trill-smart-endnodes-10: Discuss

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DISCUSS:
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This document feels tightly coupled with
draft-ietf-trill-directory-assisted-encap, even though there are no
cross-references.  If I understand the mechanisms correctly, a Smart Endnode
(discussed in this draft) can then do directory assisted encapsulation
(described in draft-ietf-trill-directory-assisted-encap).  In fact, the
encapsulation/decapsulation seems to be the main motivation in defining a Smart
Endnode.

I think then that this document also falls short in the exploration of
potential issues, so I am also balloting DISCUSS.  The same cases that I
pointed at for draft-ietf-trill-directory-assisted-encap [1] are applicable
here -- with the added caveat that the Smart Endnode, in general, has other
sources of information (learning, etc.), which means that there are potentially
more doors to close.

The Multi-homing Scenario (Section 6) adds some complexity to the ability to
check whether the Ingress RBridge is set correctly in the encapsulation.  It
would be nice to explore this case a little further and highlight the issues as
the topologies get more complex.

As I wrote in [1], I don't think that there are easy mitigations for these
issues, but at least mentioning them so that operators are aware of the risk
would be enough to clear this DISCUSS.  Given that the authors partially
overlap, it may be a good idea to solve the issue in this document (which is
the general case) and then just have the other one point this way.

[1]
https://mailarchive.ietf.org/arch/msg/trill/xZvEj_9FtSgHSp4DnKCVxr670gc/?qid=1e5a9496ac80237a3f7cc6aeea09d24d

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From: Donald Eastlake <[email-masked]>
Date: Wed, 7 Mar 2018 14:56:54 -0500

Hi Alvaro,

On Mon, Mar 5, 2018 at 4:34 PM, Alvaro Retana <[email-masked]> wrote:
> ...

There are similarities, but I'm not sure I would say that
draft-ietf-trill-directory-assisted-encap and
draft-ietf-trill-smart-endnodes are "tightly coupled".

trill-directory-assisted-encap is the best you can do with no changes
to RBridges as specified in the TRILL Base Protocol [RFC6325]. Special
end stations can do the encapsulation but edge RBridges always do the
decapsuation.

trill-smart-endnodes requires additional mechanisms in the edge
RBridges to shake hands with the smart endnode, recognize when a
destination MAC is being handled by the smart endnode and just forward
it without decapslation, etc. As a result, this also support smart
endnodes that are fine grained label aware.

> sources of information (learning, etc.), which means that there are potentially

OK, similar security consideration text improvements can presumably be
made to this draft.

> https://mailarchive.ietf.org/arch/msg/trill/xZvEj_9FtSgHSp4DnKCVxr670gc/?qid=1e5a9496ac80237a3f7cc6aeea09d24d

Thanks,
Donald
===============================
 Donald E. Eastlake 3rd   +1-508-333-2270 (cell)
 155 Beaver Street, Milford, MA 01757 USA
 [email-masked]

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From: Donald Eastlake <[email-masked]>
Date: Tue, 13 Mar 2018 16:47:03 -0400

Hi Alvaro,

A -11 version of the draft-ietf-trill-smart-endnodes draft has been
posted. Could you look at it to see if it resolves your Discuss?

Thanks,
Donald