[TriLUG] azureus/bittorrent slowdown

[Aaron Joyner]

This is also only a problem for two peers who *both* can't be reached
directly from the outside world.  Consider Alice and Bob who wish to
transfer a file via bittorrent.  As long as Alice has properly
configured her firewall to allow incoming connections, it doesn't
matter that Bob doesn't accept incoming connections, it only requires
that Bob initiate all the connections to Alice.*  When Bob wants to
transfer a file from Eve, who *also* doesn't accept incoming
connections, neither can initiate a chunk transfer.  Thus, the
inability to receive incoming connections merely limits the number of
peers Bob can communicate with.  This can have the practical effect of
reducing Bob's throughput, unless the aggregate bandwidth of the peers
in the network who accept incoming connections is greater than his
available bandwidth.

If I were a betting man... I'd say the most likely problem is that
Azureus has a bug, either in it's own code, in the version of the JVM
you're running it with, or the interaction between the two.  Carl's
suggestion of trying with another torrent client such as Transmission
is an excellent one.  You might also wish to keep an eye on memory or
CPU usage of Azureus, and see if it correlates with speed.

Happy torrenting!
Aaron S. Joyner

* - Honestly, I forget whether the bittorrent protocol is smart enough
to cause Bob to initiate connections to Alice if it's Alice who needs
a chunk that Bob has.  I think so, but I'm not certain.  Confirming
that is left as an exercise to the reader.

On Wed, Dec 19, 2012 at 3:13 PM, Lance A. Brown <lance at bearcircle.net> wrote:
> On 12/18/12 21:01, Joseph Mack NA3T wrote:
>> I just ran the NAT test on azureus and found that port 47518 (udp/tcp) is
>> blocked. Presumably I ran this test when I installed it. If it failed then I
>> probably said "well it it's uploading and downloading, what else do I need?".
>
> Yep, try putting in a manual forwarding in your linux box to send traffic for
> port 47518 to your asureus machine and see what happens.  Make sure to
> configure Azereus so that it always uses that port.  Some clients will pick a
> new random port every time they start.  That works fine if uPNP is working,
> but is a pain with manual port forwarding.
>
>>> I fixed it by manually entering the port forwards needed to allow inbound
>>> connections to my torrent program.
>>
>> let me try that.
>>
>> If it needs these, how can it work at all if I don't have them?
>
> Very poorly if at all.  Initially, while you are downloading files using
> bittorrent, things will go well.  After a while, if you can't reliably get
> inbound connections, you'll see things tail off and you won't be able to seed
> torrents worth a damn.
>
> --[Lance]
>
> --
>  GPG Fingerprint: 409B A409 A38D 92BF 15D9 6EEE 9A82 F2AC 69AC 07B9
>  CACert.org Assurer
> --
> This message was sent to: Aaron S. Joyner <aaron at joyner.ws>
> To unsubscribe, send a blank message to trilug-leave at trilug.org from that address.
> TriLUG mailing list : http://www.trilug.org/mailman/listinfo/trilug
> Unsubscribe or edit options on the web  : http://www.trilug.org/mailman/options/trilug/aaron%40joyner.ws
> TriLUG FAQ          : http://www.trilug.org/wiki/Frequently_Asked_Questions