Max connected peers / upload slot

[silent_one]

Hi guys..

I was just wondering how do I determine the nubmer to set for max connected peers. I use adsl 256/64 and got max peers set at 20 and 2 upload slots. What determines this stuff. :/

I'm tyring to squeeze out as much speed as possible!

[µtorrent-Guest]

"What determines this stuff."

Wisdom of experienced users with good knowledge about the technical stuff behind the BT protokoll.

If these are the values speed guide tells you to use for 64 kilo bits up, than use them. your own download experience as the download experience of others connected to you will benefit from them.

[silent_one]

So basically you are suggesting a method of trial and error... that's pretty cool, I can accept that...

BUT

then I got another question?!!

What are upload slots? Does it mean how many people you should be uploading to or is that something completely different?

Thank you

[µtorrent-Guest]

I'm not really suggesting T&E. You know, others who engineered this protokoll made their minds about it, they made their theoretical calculations based on the amound of data that is transmitted over this protokoll and then some T&E in "Real Life"how their mathematical calculations fit with the practical hardware out there. So no need to do the T&E by yourself if you want to prevent yourself from frustration of slow Downloads ;-)

Uploadslots:

how many people at the same timeincident will get data from you.

Its better to only have 2 slots and serve them with ~20-25 kbits then having 10 slots and serving each of them not with the theoretical ~5k but practical much less usable contentdata because of BT-traffic overhead.

[silent_one]

who engineered this protokoll made their minds about it, they made their theoretical calculations based on the amound of data that is transmitted over this protokoll and then some T&E in "Real Life"how their mathematical calculations fit with the practical hardware out there.

YES!!!! you hit the nail on the head. I wanted to know how to make these theoretical calculations i.e. how much data is sent to a user i.e. issuing a choke command or something.. Your probably asking why I would need to know this.... it's just the way I am.. can't help it.. sorry :/

[µtorrent-Guest]

In that case....

... I'm shure the protocol specs are very well documented. Go to Bram's website and search there.

[silent_one]

Thank You!!!!

Just had a nice interesting read of the protocol.. Thought I'd post some of my findings here incase any one stumbles across this and is interested..

Basically the torrent client (which in our case is μtorrent =D ) commuincates with the tracker and gets a list of peers that have the file you want.

Each peer sends his own peer_id (ip address i think) which is 20bytes

Each peer also sends a 20 byte info_hash (i think this is so the tracker and we know that everyone has the same file)

Then μtorrent looks only at x peers, were x is the max number of peers per torrent.

Choke/unchoke messages start being sent to these x number of peers.

If a peer is choked it means that you cannot upload from them (this is temporary of course)

If a peer is unchoked it means that you can download from them. :cool:

Note: just because a peer is unchoked does not mean you are not connected to them. It just means that you cannot download from them just yet.

Only 4 peers max are unchoked the rest are kept as 'backups'. If you click on the peers tab and look under the flags column you will notice a series of letters. The letter U refers to uploading and unchoked. Basically it means you are downloading from this peer. You will notice that there are no more than 4 captial U's in the list i.e. only 4 max peers are unchoked.

Keepalives are sent out every 2 minutes. These decided if to keep downloading from the current peer or choke them and unchoke another peer. The keep alice msg has no payload. I don't understand what no payload means.. could someone explain? :/

What is interesting about the bittorrent protocol is that it choses the best 4 peers to unchoke to obtain the maximum speed possible. But it also does something called optimistic unchoking every 30 seconds. Say we are downloading from 4 peers but then suddenly another 4 peers come on line with double the upload speed. Normally we wouldn't know becuase we keep sending keepalive messages to the original four peers becuase everything is going okay and we are happily downloading. However optimistic unchoking randomly unchokes a peer every 30 seconds. If a peer appears to have a high upload speed that peer is sent a kepalive message and one of the other peers is dropped (we can only have 4 maximum).

I hope I didn't make any mistake but if I did please feel free to correct me.

I changed my max peers per torrent now to 50. So every 30 seconds choke/unchoke messages happen due to optimistic unchoking. Also every 30 seconds I get an update if the peers are interested or not interested. If someone is unchoked but uninterested you cannot download from them (in other words you have unchoked them but they have choked you ) If i have 50 peers then i get 50 intereseted/uninterested msgs every 30 seconds. I don't know how big these msgs are but you can see that if you had to many peers like say 200 this would significantly affect you upload/download speed because you would be sending too much data via the choke/unchoke interested/uninterested messages.

If you are reading this and thinking this guy is talking crap then feel free to read this

http://www.bittorrent.com/documentation.myt

p.s. could someone tell me what no payload means? Also what is a handshake is it when 2 computers agree to open a connection. Is sending choke unchoke msgs a hand shake?

Don't double post.

[vanDivX]

handshake is just what it says it is except in electronic way, its done as you say to initiate connection and is equivalent to you extending your hand forward to somebody and you wait till that somebody extends his hand and grasps yours and shakes it, than you know you established - that is got his attention and you can start talking to him and he can talk back.

Typically that refers to your home modem initiating connection to your ISPs modem, they do handshaking and after that they maintain connection till its lost one way or another...

that's just to get you started, it is interesting read

in connection with this, I was wondering if the following is valid relationship:

(Global max # of connections) = (Max # of active torrents) x (Max # of connected peers per torrent)

that is, the Global max connetions should be set to value obtained by multiplying those two later terms, if you set it higher, it is redundant and if set lower, you get less than max # of connected peers per torrent in some torrents than you could otherwise get connected.

is that right?

vanDivX

[Switeck]

(Global max # of connections) = (Max # of active torrents) x (Max # of connected peers per torrent)

Is basically true. However torrents downloading AND uploading slower than 1 KB/sec don't count as active torrents but might still have connections that count against the global max connection limit.