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disparity in the download speed

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I have two computers at home with the same OS and Service Pack (Windows XP with SP2).

I do not have port forwarding enabled. And both the PC have the exact same BitComet version (1.17).

I tried to do a test. I used the same torrent on both the BitComet clients in the same internet network.

Now, to my horror/surprise I found that one PC always had a download speed of around 1-2KB/s while the other one goes upto 60KB/s.

I tried to check each and every settings and found them to be exactly the same. Even the half-open TCP limit is set to the default 10 on each.

This test I tried with many torrents and each time the result was around the same (one PC - the same one everytime, was very slow while the other PC was fast).

Can anyone please let me know why is this disparity in downloading speed when everything is same.



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Thank you kluelos & Vasy for your reply.

To answer your questions:

1) What version of BitComet are you using?

A - 1.17

2) What type of Internet connection do you have (ADSL, etc.)?


3) Do you have a modem? Do you use a router? What make and model are each one of them? Have you forwarded your port?

A - Router/Huwaei. I have not forwarded the port for both the cases. I am using my friend's connection and the port is forwarded to his PC.

5) What version of Windows, Firewall and Antivirus do you use?

A - Windows XP SP2/Symantec Protection Agent/Office Scan. I have allowed everyone to connect to the internet from the firewall. So that's not the issue.

7) For speed-related issues, please run various speed tests at a site such as speedtest.net (make sure that no other computer is using your Internet connection and that all other programs - including BitComet - are closed, during the tests). Include the results, along with the settings that you are presently using, in your post, so that we may review and offer suggestions to improve its performance.

A - The speed test shows below:

Problematic PC - Download @ 4.42 Mb/s, Upload @ 0.44 Mb/s

Good PC - Download @ 3.10 Mb/s, Upload @ 0.42 Mb/s

Now, as you can see I am getting very good speed with the Problematic PC (even better than the Good PC). I have checked every option in my BitComet, and they are same.

I don't know what to do now. Please help.


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Some really important questions which need be answered here, are:

Do you use the same port number for both clients?

Do you have a green light in BC for any of these 2 computers?

Or do you get any remote peers (on the Peers tab) for any of them?

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If I understand this correctly, these computers are not connected in the same way at the same location. One of them is in another location, possibly through a different router, possibly connected to a different ISP. Is that correct?

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Thank you greywizard and kluelos for your replies.

To answer your questions:

1. The experiment I did, had two different ports on both of them when I run them simultaneously. And same port, when I ran them one by one. Both ways, no different.

2. No, I have amber light on both the computers. Although the DHT is green on both the computers.

3. By remote peers, if you meant by in the "initiation" column, I see only local on both the computers.

4. Yes, these two PCs are in the same location (infact just a couple of feet away from each other) and connected to the same router :)


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The amber light indicates, and the absence of any REMOTE initiations confirms, that your listen ports are being blocked by one or more firewalls.

Because of that, other peers cannot initiate contact with you to offer you connections. Only replies to your requests can pass through your firewall, so your only connections will be with peers that you initiate contact with. (Don't call me, I'll call you.)

In turn, that means you will make new connections slower (because there's only one of you trying) and, odds are, you will not get the best out of all the available connections from this swarm. The ones you do get will be largely a matter of chance, a subset of the possible. Each machine will get a different subset that will be pretty random, and that would be sufficient to account for the speed differences you.

(Let me point out that your speed, even on the fast machine, is very much slower than I would expect on that connection, given a reasonable torrent status.)

If your listen port were open, then other peers' attempts to contact you would get past the firewall(s), and since there are a lot more of them than there are of you, you'd get a lot of connections pretty quickly. Your client picks and chooses from among the best available to start negotiating with.

(You can't negotiate with 'em if you don't even know they're out there.)

I believe that if you get that/those listen ports open on whatever firewalls are blocking them, then both machines will be faster and should reach approximately the same speeds, AOTBE.

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A thing to keep in mind, even if you manage to open your listening ports, is that if you run BT clients simultaneously on more than one machine of your LAN then they will divide among them the downloading bandwidth and especially the upload bandwidth.

So you need to take that into account when setting the Connection options for each one of them.

Furthermore, I'm not sure that it's a very good idea to run the same torrent (except for test's purpose) on both machines simultaneously since they will sort of compete for peers (due to the limited number of uploading slots of each peer at any moment); they use the same public IP and appear to the tracker and DHT as a single IP.

Instead I'd run different torrents on each machine, if you really want to run both clients at the same time.

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