Maximum Simultaneous Connections. Torrents & P2P.

Those of you who use torrents and do some heavy P2P sharing know that
many routers cant handle alot of simultaneous connections or they
'melt down' and need to be reset. I'm looking for more info &
benchmarking results for wireless & wired routers, similar to these
two links:

http://www.smallnetbuilder.com/route...30-330-124.png
http://www.roumazeilles.net/news/nw/news0068.php

Anyone know of links that discuss or benchmark routers like this? Any
similar links would be appreciated.

On 14 Feb 2007 17:03:09 -0800, (E-Mail Removed) wrote:

>Those of you who use torrents and do some heavy P2P sharing know that
>many routers cant handle alot of simultaneous connections or they
>'melt down' and need to be reset. I'm looking for more info &
>benchmarking results for wireless & wired routers, similar to these
>two links:
>
>http://www.smallnetbuilder.com/route...30-330-124.png

Wrong. The chart is from a review of small wireless routers and lists
the number of simultaneous *WIRELESS* connections that can be handled.
That's basically the number of MAC addresses that can be bridged via
wireless before the access point section dies.

What Bittorent and others do is open a huge number of simultaneous IP
ports which causes the router to run out of buffer space. That's
quite different than running out of table space for MAC addresses.

>http://www.roumazeilles.net/news/nw/news0068.php

Blah. Anecdotal guesswork. Some of the reports couldn't even get the
hardware and firmware versions correct.

> Anyone know of links that discuss or benchmark routers like this? Any
>similar links would be appreciated.

Yes. However most of the crap I've read is no better than the above
article. Basically, they make no effort to do any form of organized
testing. Never mind that Microsoft has had a Bittorrent simulator for
a while. Test first, then publish.

The basic problem is NOT that the router can't handle the large number
of streams. It's that the users P2P software configuration allows a
larger number of streams than the router can easily handle. If the
software was configured for an infinite number of streams (as some
clients are by default), the even the worlds best router doesn't have
enough RAM to handle all the required buffer space. Reduce the number
of streams and connections the software can accept and all but the
most gutless router will handle the load.

MS Bittorrent simulator:
<http://research.microsoft.com/research/downloads/Details/20d68689-9a8d-44c0-80cd-66dfa4b0504b/Details.aspx>

Analyzing and Improving BitTorrent Performance
<http://www.research.microsoft.com/~padmanab/papers/msr-tr-2005-03.pdf>

Some Observations on BitTorrent Performance
<http://research.microsoft.com/%7Ecormac/Papers/Sigmetrics05.pdf>

File Swarming Systems
<http://research.microsoft.com/~milanv/coupons.htm>

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558 (E-Mail Removed)
# http://802.11junk.com (E-Mail Removed)
# http://www.LearnByDestroying.com AE6KS

On Thu, 15 Feb 2007 04:57:34 GMT, Jeff Liebermann
<(E-Mail Removed)> wrote in
<(E-Mail Removed)>:

>The basic problem is NOT that the router can't handle the large number
>of streams. It's that the users P2P software configuration allows a
>larger number of streams than the router can easily handle. If the
>software was configured for an infinite number of streams (as some
>clients are by default), the even the worlds best router doesn't have
>enough RAM to handle all the required buffer space. Reduce the number
>of streams and connections the software can accept and all but the
>most gutless router will handle the load.

Much depends on the client. Azureus <http://azureus.sourceforge.net/>,
one of the best Bittorrent clients, has reasonable defaults for the
number of connections:
* Max connections per torrent: 50
* Max connections globally: 250
Those should be reasonable values for any decent router IMnsHO. If your
router can't handle that, then get a better router. Seriously.

'Course there might still be a problem if multiple computers behind the
router are running Azureus at the same time.

Regardless, it's simply sloppy development and programming that results
in routers falling over due to too many connections. Proper engineering
would determine the maximum safe number of connections, and enforce that
maximum gracefully, reasonably allocating and expiring connections by
connected client.

--
Best regards, FAQ for Wireless Internet: <http://Wireless.wikia.com>
John Navas FAQ for Wi-Fi: <http://wireless.wikia.com/wiki/Wi-Fi>
Wi-Fi How To: <http://wireless.wikia.com/wiki/Wi-Fi_HowTo>
Fixes to Wi-Fi Problems: <http://wireless.wikia.com/wiki/Wi-Fi_Fixes>