why do I show download and upload status when I have no activity?

[airtas]

I was wondering why would I show DHT nodes and upload and download activity if I am not doing anything?

[airtas]

and is T for total? currently I am showing T: 296.4 kb under downloads

[paintball9]

Nodes are connections, they always use bandwidth (minimal though) to keep the connection alive, and when you add a torrent it sends a request across those nodes for peers with the same torrent. Like a tracker but it doesn't record stats and if one goes down it doesn't take the whole network with it. And yes T is the total transferred, Both down and up have one.

[Switeck]

DHT also passes requests through uTorrent to find other BT clients with torrents matching the requests by hash. If you're connected to lots of nodes at once, the number of requests per second in theory should be higher and thus bandwidth used higher. This is even if you're not sharing anything at once.

[airtas]

how does a node know when to be used?

so it is normal to have nodes open even if I have no torrents?

[paintball9]

DHT always runs (if it's enabled), basically it just adds you to a massive list of people, some of them may be running the torrent you're looking for, so when you add a torrent it sends the unique hash of that torrent out to all the nodes requesting peers, and anyone who has that torrent running gets referred to you. In the same way when someone else requests peers for a torrent, the request goes to you, regardless of whether or not you're have it. If you don't it just gets ignored, if you do then you get referred to them. With a distributed system it doesn't rely on just one machine (a tracker) to keep track of peers, but rather if a node goes down it still works.

Yes it is very normal to have nodes open. It makes connecting to peers faster once you do add a torrent. It doesn't really do a whole lot when there aren't any torrents anyways. Just the odd keep alive packet and request.

If you don't want this system you can disable it in preferences globally. (private torrents already block this function) Keep in mind though that if a torrent comes up without a tracker it may not work without DHT. DHT can also be used to find peers who choose to not use trackers but still use DHT.