Re: [multipathtcp] Timestamp option for Multipath TCP

Olivier Bonaventure <Olivier.Bonaventure@uclouvain.be> Wed, 29 March 2017 13:06 UTC

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Reply-To: Olivier.Bonaventure@uclouvain.be
References: <c030efb2-5a1f-9ec9-a214-c302ebfb151f@uclouvain.be> <CAO249yesLeyKU_1ycFQ1YP093kmhe-Ng6ZN9Du5g8ofp=CKT0Q@mail.gmail.com>
To: Yoshifumi Nishida <nishida@sfc.wide.ad.jp>
Cc: multipathtcp <multipathtcp@ietf.org>
From: Olivier Bonaventure <Olivier.Bonaventure@uclouvain.be>
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Date: Wed, 29 Mar 2017 15:05:58 +0200
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Subject: Re: [multipathtcp] Timestamp option for Multipath TCP
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Yoshifumi,
>
> I personally prefer 1, but I might prefer some generic framework as I am
> guessing there will be other cases that we don't want timestamps for PAWS.
>
> BTW, are we sure that DSN option can provide protections against PAWS?
> We cannot guarantee DSN option appears on all segments..

If there is a valid DSS option, either DSN mapping or DSN ack, then the 
segment cannot be a replay of an old segment. If we use long mappings, 
then there are two different situations :

- long mapping but TSO copies the DSS option inside each packet
- long mapping and no TSO

In the second case, we need to ensure that each packet contains some 
information that allows to support PAWS. DSS and timestamp would work


Olivier