FTP Connections maximum?

Posted on 2004-11-03
Last Modified: 2008-01-09
Hello, lets consider you run dot com and other mass downloading websites and lets consider that you have one IIS server.  

What is a realistic maximum FTP connections?  

What sort of transfer rate would that be?

Lets consider that you are on an Host with 100Mbit/sec connected to the net.  I am wondering how much an ISP would throttle your server so you don't max-out their internet pipe.  And IIS FTP service, would it strugle with over 25 connections at a time?  Whats realistic?


Question by:DaveRowland
    LVL 34

    Expert Comment

    What kind of hardware are you running on the server?

    How much memory and how fast a connection to the host ISP?

    As far as Concurrent FTp connections I believe the IIS FTP service has been tested with upwards of 10,000 concurrent connections.

    There is a theoretical upper limit of somewhere around 60,000 connections simply becuase you'd run out of ports/sockets, but the realistic maximum is probably more in the 5-10,000 reange depending on what hardware you're using.

    As far as the ISP side of things, that will depend entirely on your ISP and your contract with them.

    Dave Dietz
    LVL 1

    Author Comment

    Dave, we not running anything currently, but if you want to see what I am doing, then see if you can see my other questions posted.  

    I am supprised tat 10,000 concurrent connections, I just feel that sort of figure to be impossible on a standard FTP/IIS host deal.

    I guessed processor/memory would come into it, but it is judging what is possible with deals out there.  I could be transfering 400-2000 concurrent connections of 10-20MB but want to know if in practice this is realistic on an American or UK host.  Would I just flood the host?  Anyone got any experience of this?

    LVL 34

    Accepted Solution

    If you have enough memory to handle the creation of 10,000 sockets (16k each if I remember correctly) as well as enough memory to reliably run the rest of everything else on your server, you have enough CPU horsepower to back it up (a pair of higher end Xeon's should do) and a fastenough pipe to handle the traffic 10,000 connections isn't unreasonable.

    Whether you'd flood you host or not depends on the host.  Mom and Pop or local smaller ISPs might not be able to handle this kind of flat out traffic but any larger reputable host should be able to do it, however if you're looking at having 1000 concurrent connections running at 20MB/s as your average traffic I would suggest you work out some sort of flat pricing plan ahead of time with whatever host you choose to work with.

    Dave Dietz

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