[OLPC Networking] Recommendation I3

[Ricardo Carrano]

Hi Bill,

On Thu, Aug 14, 2008 at 11:15 AM, Bill Mccormick <billmcc at nortel.com> wrote:
> Hi Ricardo,
>
> Is there a view on how much of the traffic uses TCP as a transport
> instead of UDP?
>
> TCP congestion mgt will help to reduce load when the network becomes
> congested.   It looks like your simulations assume no TCP congestion
> management.

These tests were designed to be payload agnostic. We are measuring
(not simulating actually but collecting real data) the efficiency of
the rate adaptation algorithm. We see that when it faces congestion it
does not react properly. It should make a distinction between a frame
lost due to congestion or due to poor link quality.

The TCP congestion algorithm is not under study here. But, I agree
that this is an important issue, since it is actually highly
inadequate for our mesh scenario, because of the way it tends to
interpret everything as congestion.

So, the irony is that the rate adaptation logic makes the mistake of
considering that everything that is lost is lost due to poor link
quality, while TCP does the opposite, considering that everything is
congestion, which is also a mistake.

Cheers!
Ricardo




>
> Bill
>
> -----Original Message-----
> From: networking-bounces at lists.laptop.org
> [mailto:networking-bounces at lists.laptop.org] On Behalf Of Ricardo
> Carrano
> Sent: Monday, August 11, 2008 7:19 PM
> To: networking at lists.laptop.org
> Subject: [OLPC Networking] Recommendation I3
>
> Hello,
>
> Those interested, please take a look at:
> http://wiki.laptop.org/go/Wireless_Rate_Adaptation_Logic
>
> I am collecting comments on the subject and should issue a formal
> recommendation (which algorithm to implement, for instance) after a
> period of two weeks collecting comments and after discussing that in
> person with to M.Bletsas at 1CC by the end of August. For now, the
> recommendation is "change the rate adaptation logic"
>
> Looking forward to reading your comments and suggestions.
>
> Cheers!
> Ricardo
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