Subject: [multipathtcp] Unknown TCP Options through FWs

From: Apostolis Salkintzis <[email-masked]>
Date: Tue, 31 May 2011 13:45:32 +0300

Hi All,

Has anyone managed to conduct MPTCP experiments on live mobile networks?
Seems like FWs on such networks are typically configured to drop TCP
segments with unknown options, so MPTCP is unlikely to work. Anyone have had
such experience?

Thank you,
Apostolis
-- 
*
*

---

From: Mark Handley <[email-masked]>
Date: Wed, 1 Jun 2011 01:10:09 +0100

Michio Honda has conducted quite extensive experiments on precisely
this issue.  His results are not yet published, but the brief summary
is that more than 85% of paths sampled pass unknown options on port
80.  On less popular ports the number is more like 95%.  And his
results conclude that the mechanisms built in to MPTCP assure safe
fallback to regular TCP in all the cases observed.

For cellular networks, the numbers are slightly lower.  12 out of 20
passed unknown options on port 80, and 16 out of 20 passed them on
other ports.  In all cases, nothing preventing fallback to regular TCP
was observed.

Clearly on some networks, MPTCP will provide no win.  I guess that's
no surprise seeing as no operator has engineered with MPTCP in mind,
and a sizable minority block anything unexpected.  But even on
cellular nets, and even amongst those, on port 80 which is heavily
special-cased, they majority do actually pass MPTCP options.

It is of course possible that the 142 networks Michio's results are a
biased sample (I cannot see why, but cannot rule it out), and clearly
they provide an uneven sampling by country (Japan, UK, US and Germany
have most results in that order, but he did sample nets in 24
countries, so the results are pretty broad).  Overall I think the
results provide a very valuable insight.

 - Mark

On 31 May 2011 11:45, Apostolis Salkintzis <[email-masked]> wrote:
> _______________________________________________
> multipathtcp mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/multipathtcp
>
>