Re: [trill] I-D Action: draft-ietf-trill-over-ip-01.txt

Donald Eastlake <> Tue, 15 July 2014 17:01 UTC

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From: Donald Eastlake <>
Date: Tue, 15 Jul 2014 13:01:07 -0400
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Subject: Re: [trill] I-D Action: draft-ietf-trill-over-ip-01.txt
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Hi Joe,

Sorry for delay in response. I was traveling and am now being kept
busy at a meeting in San Diego.

On Mon, Jul 14, 2014 at 1:12 PM, Joe Touch <> wrote:
> Hi, Donald,
> I raised these concerns at the time the doc was proposed as a WG item, and
> these issues were never really addressed. ...

Well, you get to decide whether you believe your concerns have been
adequately addressed. And the WG Chairs get to decide what the
consensus of the WG is. None of your concerns have been, in my
opinion, technical, in the sense of arguing that something will not
work or will not be interoperable. Your concerns appear to me to be
matters of opinion, such as whether something is "needed", on which
reasonable people might have different opinions.

To the extent that your concern is that someone will think that using
TRILL over IP somehow, in itself, significantly changes TRILL's
scaling characteristics, I do not think there is anything in this
draft or any TRILL document saying that a choice of link protocol on
one or more links in a TRILL campus will do that. In any case I'd be
fine with adding a sentence or two to Section 2 of the draft,
clarifying this.

> I see your points about keying, zero-config, etc., but those argue for a new
> layer to support TRILL use of existing encapsulation, not for a totally new
> encapsulation.

I do not agree with your analysis. Creating a "new layer" seems to me
to be a lot of unnecessary work compared with using the method of
transporting X over IP by using UDP of which there are multiple
examples. ((Not really related to any of this but I just recently
noticed that RFC 768 which specifies UDP is almost 34 years old and
that no need to update, obsolete, or file an errata against it has
occurred so far.))

> Although I appreciate the IESG's "let a thousand flowers bloom" viewpoint,
> the result is a thousand wheels get reinvented, and it's nearly impossible
> to ensure that past mistakes are not repeated.

I don't think that there are 1,000 link protocols and I don't think
that a guarantee that no mistake be made should be a condition for a
standards effort.

In any case, the TRILL WG has thus far specified how to send TRILL
directly over 2 technologies, Ethernet (RFC6325) and pseudowires
(RFC7172), and the PPPEXT WG specified how to send TRILL over PPP
(RFC6361). This draft would increase the universe of link protocols
directly, interoperable, and efficiently usable by TRILL for 3 to 4 by
adding IP, which seems to me to be a particularly prominent and widely
deployed technology. I do not remember any proposal being made thus
far in the TRILL WG for any further TRILL over X standards track

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

> Joe
> On 7/11/2014 1:02 PM, Donald Eastlake wrote:
>> On Tue, Jul 8, 2014 at 6:28 PM, Joe Touch <> wrote:
>>> Hi, all,
>> Hi Joe,
>> First off, I'd like to thank you for your contributions to this draft.
>> In particular, section 10.1 on Recursive Ingress was included in
>> response to comments that, as I recall, came primarily from you.
>>> I don't see TRILL as needing a specific solution, given ethernet can
>>> already
>>> be bridged using IP any number of ways (including GRE or L2VPN
>>> approaches).
>> Well, I suppose you would get different answers from different people
>> as to whether or not having convenient default security keying
>> leveraging IS-IS keying, zero configuration under some circumstances,
>> saving 14 or 18 or so bytes on every packet, having protection against
>> recursive ingress, etc., are worth it. But in the context of TRILL,
>> this has already been decided. TRILL over IP is specifically part of
>> the work in the TRILL Charter, that Charter was approved by the TRILL
>> WG and the IESG, it has been determined that there is a TRILL WG
>> consensus to use UDP encapsulation, and, in my opinion, most of the
>> work, although not all of it, has already been done as per this draft.
>> Thanks,
>> Donald
>> =============================
>>   Donald E. Eastlake 3rd   +1-508-333-2270 (cell)
>>   155 Beaver Street, Milford, MA 01757 USA
>> _______________________________________________
>> trill mailing list