Re: [multipathtcp] Timestamp option for Multipath TCP

Olivier Bonaventure <Olivier.Bonaventure@uclouvain.be> Fri, 07 April 2017 18:59 UTC

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Reply-To: Olivier.Bonaventure@uclouvain.be
References: <c030efb2-5a1f-9ec9-a214-c302ebfb151f@uclouvain.be> <20170329151456.GE2779@dhcp-8507.meeting.ietf.org>
To: Christoph Paasch <cpaasch@apple.com>
Cc: multipathtcp <multipathtcp@ietf.org>
From: Olivier Bonaventure <Olivier.Bonaventure@uclouvain.be>
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Date: Fri, 7 Apr 2017 15:47:44 +0200
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Archived-At: <https://mailarchive.ietf.org/arch/msg/multipathtcp/e8iVirnDeLDNNRVU65DqI6Uuv6s>
Subject: Re: [multipathtcp] Timestamp option for Multipath TCP
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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.



Olivier