Re: Deadlocking in the transport

Martin Thomson <martin.thomson@gmail.com> Thu, 18 January 2018 07:21 UTC

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From: Martin Thomson <martin.thomson@gmail.com>
Date: Thu, 18 Jan 2018 18:21:35 +1100
Message-ID: <CABkgnnW=75JxULpKgjO3K8Ry1E2umDq4icYJS3SqetRSMjamAw@mail.gmail.com>
Subject: Re: Deadlocking in the transport
To: Ian Swett <ianswett@google.com>
Cc: Jana Iyengar <jri@google.com>, QUIC WG <quic@ietf.org>, Roberto Peon <fenix@fb.com>
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Yes, what Ian said (and more to what Jana said).  I think that we've
some proportion of the working group who are operating on one set of
assumptions and another on a different set of assumptions on this
subject.  Until now, that didn't bother me much.  After all, that's
normal for a whole range of issues.

Now there's a concrete problem, so let's dig into this properly.

FWIW, I don't think that we'll resolve this particular issue in
Melbourne, but I hope that we can at least start that process.  This
promises to be interesting.

On Thu, Jan 18, 2018 at 9:36 AM, Ian Swett <ianswett@google.com>; wrote:
> +1 million
>
> On Wed, Jan 17, 2018 at 4:43 PM, Jana Iyengar <jri@google.com>; wrote:
>>
>> We will discuss this at the interim, but one comment, inline.
>>
>>>
>>> In part, it's the ignorance of the intermediary that causes this
>>> particular problem.  If the intermediary was aware of the protocol
>>> details then it might be able to recognize and avoid these situations,
>>> but that seems a little too much to expect of intermediaries. Ruling
>>> out the entire class of intermediary that operates purely at the
>>> transport layer is extremely harsh.
>>>
>>> What is more likely here is that we describe this situation, explain
>>> that it is impossible to prevent in the presence of intermediation,
>>> and explain how to kill the right streams in order to ensure forward
>>> progress doesn't stall indefinitely.
>>
>>
>> Exactly because intermediaries make things difficult, it's important to be
>> certain that the intermediary behavior we are discussing is one that there's
>> a strong argument for supporting. We have spent countless cycles on
>> designing around uncertain and unknown intermediary behaviors in various
>> parts of the IETF, and I don't want us to recreate these boogeymen. I think
>> it's reasonable to rule out classes of middleboxes if we don't have strong
>> arguments for supporting them.
>>
>
>