Re: [Tsv-art] [v6ops] [Last-Call] Tsvart last call review of draft-ietf-v6ops-ipv6-ehs-packet-drops-05

Fernando Gont <fgont@si6networks.com> Mon, 22 February 2021 18:14 UTC

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To: Tom Herbert <tom@herbertland.com>, Nick Hilliard <nick@foobar.org>
Cc: Brian E Carpenter <brian.e.carpenter@gmail.com>, Gorry Fairhurst <gorry@erg.abdn.ac.uk>, tsv-art@ietf.org, last-call@ietf.org, draft-ietf-v6ops-ipv6-ehs-packet-drops.all@ietf.org, IPv6 Operations <v6ops@ietf.org>
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From: Fernando Gont <fgont@si6networks.com>
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Date: Mon, 22 Feb 2021 14:33:29 -0300
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Subject: Re: [Tsv-art] [v6ops] [Last-Call] Tsvart last call review of draft-ietf-v6ops-ipv6-ehs-packet-drops-05
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Tom,

On 22/2/21 13:29, Tom Herbert wrote:
> On Mon, Feb 22, 2021 at 8:23 AM Nick Hilliard <nick@foobar.org> wrote:
>>
[....]
> I understand the purpose of the draft, however, IMO, for the problems
> that are described there is insufficient detail and scope to draw any
> meaningful conclusions or take away any new insights.

Then I guess we disagree. One of the most commonly questions asked in 
this contact is "But... why do routers look inside packets?" -- and this 
document answers that question, along with the challenges it represents.

Note: in a thread on specific transports you also asked what information 
routers process. And this document also answers such question.



> When the draft
> mentions that routers might drop packets because packets are too long,
> then the obvious question is what exactly is too long.

And the obvious answer is that that depends on a vendor/model basis. If 
the router only copies the mandatory header to a buffer, then "too long" 
might be "1 EH".


> Since this
> draft is discussing real implementation and not theory, it seems like
> measuring the extent and determining the real operational parameters
> of the problems, like what a useful minimum length of header chains
> is, seems straightforward either by experimentation or simply polling
> router vendors to see what they support.

It performs a qualitative analysis of the problem.

What you ask seems to be either RFC7872bis, or a document that would 
complement RFC7872.

... but certainly out of the scope of this document.


Thanks,
-- 
Fernando Gont
SI6 Networks
e-mail: fgont@si6networks.com
PGP Fingerprint: 6666 31C6 D484 63B2 8FB1 E3C4 AE25 0D55 1D4E 7492