Re: [Stackevo-discuss] Fwd: New Version Notification for draft-welzl-irtf-iccrg-tcp-in-udp-00.txt

Michael Welzl <> Wed, 23 March 2016 23:43 UTC

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From: Michael Welzl <>
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Date: Thu, 24 Mar 2016 00:43:07 +0100
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To: Joe Touch <>
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Subject: Re: [Stackevo-discuss] Fwd: New Version Notification for draft-welzl-irtf-iccrg-tcp-in-udp-00.txt
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> On 24. mar. 2016, at 00.05, Joe Touch <> wrote:
> On 3/23/2016 4:42 AM, Michael Welzl wrote:
>> I'm sending this here as well because it relates to the idea of "running the Internet over UDP" (which, I noticed, is presentation that Brian will give in MAPRG: ).
>> This draft explains how we think it should be done with TCP; we believe that it can have quite significant positive side-effects, mainly because of the opportunity to combine the congestion controls of multiple connections.
> Ick.
> We went through this before multiple times. One notable was the impact
> of chunking and muxing in HTTP, effectively reinventing IP inside.
> "A person with one watch always knows what time it is. A person with two
> is never sure.”

I don’t think I follow this, sorry.

> I can't imagine what combined congestion control of TCP would mean
> inside the network - we had a hard enough time defining it for either
> TCB sharing or the Congestion Manager just at the endpoints.

I don’t get this either; it sounds like a misunderstanding?

So the encapsulation here is just meant to force packets to take the same path - else the Congestion Manager may be doing something pretty wrong.
The sender-side behavior then couples connections; this could be done via the Congestion Manager, or in a way similar to TCB sharing, or with our algorithm (which is somewhat similar to TCB sharing). That’s why we call it “example algorithm” - think of this as “UDP encapsulation forces TCP connections on the same path so we can use the CM”. That’s really all it is.