Re: [tsvwg] New Version of draft-ietf-tsvwg-transport-encrypt (12)

[Gorry Fairhurst <[e-mail]>]

On 16/03/2020 15:21, Tom Herbert wrote:
> On Mon, Mar 16, 2020 at 7:52 AM Gorry Fairhurst <[e-mail]> wrote:
>>
>> On 16/03/2020 13:06, Eric Rescorla wrote:
>>
>>
>>
>> On Mon, Mar 16, 2020 at 2:36 AM Gorry Fairhurst <[e-mail]> wrote:
>>> Ekr,
>>>
>>> On 15/03/2020 13:19, Eric Rescorla wrote:
>>>
>>> Let me try to expand my point a bit.
>>>
>>> Longstanding practice is for entities in the middle of the network to
>>> use signals that were intended for the endpoint for their own
>>> purposes.  With QUIC (and a lesser extent SCTP/DTLS), those signals
>>> are being encrypted and thus unavailable to those non-endpoint
>>> entities; this draft is mostly devoted to documenting the negative
>>> impact of that change on the operations of those entities.
>>>
>>> I disagree that this is "documenting the negative impact of that change".
>>>
>>> The draft is about how this protocol information has and is being used. As long as I can remember, there has been devices that utilise some of this information, at the edge of an enterprise there is often at least one device with this role; within a managed network there are devices; etc. If the trend to use encrypted methods continues, some of these practices need to be re-assessed, and the functions more widely understood than in an era when nearly everything was thought to be TCP or "multimedia".
>>
>> I'm not sure what you're arguing here. What I said above is that
>> this draft was "mostly devoted to documenting the negative
>> impact of that change on the operations of those entities."
>> In other words, it lists a bunch of things that people do now
>> that will stop working. Do you not think that much of the
>> material in this draft is of that form?
>>
>> -Ekr
>>
>> So the conclusion, para 2 states:
>>
>> "   This document has described some current practises, and the
>>     implications for some stakeholders, when transport layer header
>>     encryption is used.  It does not judge whether these practises are
>>     necessary, or endorse the use of any specific practise.
>>
> Gorry,
>
> Section 5.2 states:
>
> "Current measurement results suggest that it could currently be
> undesirable to rely on methods requiring end-to-end support of network
> options or extension headers across the Internet."
>
> That _is_ a subjective judgment

That would be better to reference 6Man debate - however, the words are 
chosen carefully: "to rely upon ... across the Internet"

Prievously David suggested to you:

"Additional considerations apply to use ofmethods requiring end-to-end 
support of network options or extension headers across the Internet.  
IPv4network options may not be supported (or may utilize a slower 
processing path) and some IPv6 networks have been observed to 
dropnpackets that set an IPv6 header extension (e.g., results from 2016 
in [RFC7872 <https://tools.ietf.org/html/rfc7872>])."


- if you think that needs more explanation, we could perhaps expand a 
little more about the IETF view on this, please suggest an alternative.

(Editor-hat off: I'm pretty sure Extension Headers are viable in some 
places, and not currently in other places, expecting this to work 
end-to-end could be unduly pessimistic. Anticipating this would never 
work would be wrong also.)

>   about a technique that is not
> currently used with little discussion on why they're undesirable or
> what needs to be done to make them desirable.  As I've said before, I
> think the document is too easily dismisses this alternative.
You think this dismissses this? I don't believe that was an intent. 
Would it help to suggest text that includes: RFC6564
or perhaps: {RFC8250; draft-ietf-ippm-ioam-ipv6-options; 
draft-ietf-6man-segment-routing-header}?


> If the
> point of this document is to describe the implications of transport
> header encryption without any diligent consideration of alternatives
> to expose the necessary transport information to the network, then I
> suggest that the discussion of extension headers and other
> alternatives should be removed and deferred to other documents.
> Tom
>
Gorry
>> I agree many existing tools would stop working if IPsec formed the majority of traffic, same for QUIC. I think when considering what to do next, it can be useful to work from the current position and understand the implications of changes that are being proposed/used/whatever.
>>
>> At least from my personal position, this document was providing some input to that thinking. So, I do not understand your issue.
>>
>> Gorry