Re: [multipathtcp] Timestamp option for Multipath TCP

Christoph Paasch <cpaasch@apple.com> Fri, 07 April 2017 19:04 UTC

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From: Christoph Paasch <cpaasch@apple.com>
In-reply-to: <de9d1418-2bc5-1790-865d-19778ba80c88@uclouvain.be>
Date: Fri, 07 Apr 2017 12:04:31 -0700
Cc: MultiPath TCP - IETF WG <multipathtcp@ietf.org>
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References: <c030efb2-5a1f-9ec9-a214-c302ebfb151f@uclouvain.be> <20170329151456.GE2779@dhcp-8507.meeting.ietf.org> <de9d1418-2bc5-1790-865d-19778ba80c88@uclouvain.be>
To: Olivier Bonaventure <Olivier.Bonaventure@uclouvain.be>
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Subject: Re: [multipathtcp] Timestamp option for Multipath TCP
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> On Apr 7, 2017, at 6:47 AM, Olivier Bonaventure <Olivier.Bonaventure@uclouvain.be> wrote:
> 
> Christoph,
> 
>> 
>>> 2. Define a new Multipath TCP option to carry timestamps. The utilisation of
>>> this option would be included in Multipath TCP and thus no option besides
>>> MP_CAPABLE would need to be included in the SYN.
>> 
>> I like this approach, because it seems to me to consume less option-space.
>> 
>> How would this timestamp look like in the DSS-option?
> 
> The DSS option has several flags that are unused. We could easily define two flags to indicate the presence of locally generated timestamp and echoed timestamp.
> 
> > Would it still be 32-bits?
> > I think we can make it less than 32-bits, right?
> 
> I'm not sure that 32 bits would be required if the timestamp is only used for rtt measurements and not for PAWS.

Yes, that sounds good to me!


Christoph