Re: [multipathtcp] Questions on https://tools.ietf.org/html/draft-boucadair-mptcp-plain-mode-09

Olivier Bonaventure <Olivier.Bonaventure@uclouvain.be> Fri, 11 November 2016 15:05 UTC

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To: philip.eardley@bt.com, multipathtcp@ietf.org
From: Olivier Bonaventure <Olivier.Bonaventure@uclouvain.be>
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Date: Fri, 11 Nov 2016 16:04:56 +0100
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Subject: Re: [multipathtcp] Questions on https://tools.ietf.org/html/draft-boucadair-mptcp-plain-mode-09
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Phil,

Let me complement some of the answers provided by Med

> If I get it right, on path means that you guarantee the first subflow
> goes through the proxy – what happens if it doesn’t?

yes, the underlying network guarantees this. Otherwise, there will be a 
fallback to regular TCP.

>
> what benefit does having this extra on-path (implicit mode) mechanism
> bring? (I know there’s been some discussion on this, is there a summary
> of the conclusion?)
>

The main benefit that network operator see with an on-path mechanism is 
that the addresses that are used by the clients are visible to the 
servers. This simplifies operations since addresses do not change inside 
the network. If the operator uses Netflow/IPFix, needs to perform LI, or 
debug problems, he sees packets with the correct source and destination 
addresses.


Olivier