Re: [ledbat] "Oh Noes, the Internetz will Melt Down..."

["Saverio Mascolo" <[e-mail]>]

i guess uTP could be similar to TCP santa cruz...forward Tfw is monitored so
that Tfw  increasing trigger the stop of the tcp probing phase. at that time
you may set the cwnd in different way...
is also utp implemneting rate-based features?

best
saverio

On Tue, Dec 2, 2008 at 9:30 AM, Stanislav Shalunov <[e-mail]>wrote:

> Some clarification of terminology --
>
> uTP is, technically, a transport framing over UDP.  Congestion control used
> is, indeed, what I described in Minneapolis.
>
> DNA is the BitTorrent Inc commercial product for content delivery.  The
> protocol is BitTorrent, but DNA is a closed system with only one tracker and
> only one client implementation.  It uses only uTP for transport.
>
> uTorrent is a free implementation of the BitTorrent protocol distributed by
> BitTorrent Inc.  The new version, 1.9, uses uTP along with TCP.
>
> So the new version of uTorrent more widely deploys the transport, and the
> congestion control (both referred to as uTP in the quote below), already
> used in DNA.  It is designed to be less aggressive than TCP and has been
> useful to reduce latency in DNA.
>
> -- Stas
>
>
>
>
> On Dec 1, 2008, at 8:23 AM, Lars Eggert wrote:
>
>  On 2008-12-1, at 17:56, Nicholas Weaver wrote:
>>
>>> The typical Fear Mongering "UDP Death Uhz Da Internetz":
>>> http://www.theregister.co.uk/2008/12/01/richard_bennett_utorrent_udp/
>>>
>>
>> Wow. Talk about jumping to conclusions. That is quite an "article".
>>
>>  However, the question is, does anyone have insight into the "uTP"
>>> congestion control protocol and what it is actually doing?
>>>
>>
>> See http://forum.utorrent.com/viewtopic.php?id=49813
>>
>> "What is in 1.9:
>> uTP, the micro transport protocol. This UDP-based reliable transport is
>> designed to minimize latency, but still maximize bandwidth when the latency
>> is not excessive. We use this for communication between peers instead of
>> TCP, if both sides support it. In addition, we use information from this
>> transport, if active, to control the transfer rate of TCP connections. This
>> means uTorrent, when using uTP, should not kill your net connection - even
>> if you do not set any rate limits.
>>
>> What was in 1.8.1:
>> uTP, but connection attempts were not initiated by default, and there was
>> no control over TCP as described above. You can enable it, but likely you
>> will see the uTP connections not transfering much data, because they are
>> pushed out of the way by TCP."
>>
>> This last bit sounds a lot like if uTP is is using some sort of
>> less-than-best-effort CC. (I believe someone mentioned in Minneapolis that
>> utorrent would implement BitTorrent's DNA - maybe this is it?
>>
>> Lars
>>
>>
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>
> --
> Stanislav Shalunov
>
>
>
>
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-- 
Prof. Saverio Mascolo
Dipartimento di Elettrotecnica ed Elettronica
Politecnico di Bari
Via Orabona 4
70125 Bari
Italy
Tel. [phone]
Fax. [phone]
email:[e-mail] <[e-mail]>

http://www-dee.poliba.it/dee-web/Personale/mascolo.html


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