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Thread: USB to USB Networking in Knoppix

  1. #1
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    USB to USB Networking in Knoppix

    To make a very long story short, I'm trying to recover a 17GB XP backup
    from a damaged (damaged data structures, not damaged hardware)
    USB disk.

    Knoppix can read the NTFS partition just fine - XP can't . I'm
    trying to copy the backup on to an XP machine that has enough space;
    once I do that I'll be able to restore it and move on.

    Using Samba on Knoppix to copy the file over ordinary, full-duplex
    100 BaseT seems like it will take several days. This seems to be a
    known problem (excessive early collisions) that M$ blames on overly
    aggressive network cards.

    So, I want to use a USB-to-USB network hub to move the data.

    The USB hub is recognized by Knoppix and visible in usbview as well as
    in the system messages. However, I can't deduce the device name
    from usbview.

    ifconfig -a does not show the USB hub.

    So, how do I configure the USB hub as a network interface?

    I've looked at linux-usb.org and I can't quite grasp the solution. Presumably I need to find another module and load it?

    knoppix version 2.4.26

  2. #2
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    can't you start a ftp-server on the linux-machine, and get it via ftp?

  3. #3
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    Re: USB to USB Networking in Knoppix

    Quote Originally Posted by 23skidoo
    ...Using Samba on Knoppix to copy the file over ordinary, full-duplex 100 BaseT seems like it will take several days. This seems to be a
    known problem (excessive early collisions) that M$ blames on overly
    aggressive network cards....
    There certainly were some problems with network cards that didn't follow the timing specs and could cause problems like this years ago, but that was on a 10 mbit coax system that actually did have collisions. With twisted pair 100 Base T cards and pretty much everyone using switches rather than hubs now a'days, it's hard to see what your packets are having collisions with.

    Sorry, I don't have any answers for you on USB networking; particularly across two different platforms (Linux to XP). But I do doubt that USB will be easy to resolve; I would sugget that you look at what is really causing your 100 Base T system to be so slow and see if you can't work around that.

  4. #4
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    ftp has the same problem; it runs over the same interface.

    As I understand it, the problem is that the ack from the receiving side
    collides with the next packet from the sender. But I just know what I
    read on the web. TheM$ KB article mentions XP

    http://www.petri.co.il/speed_up_netw...windows_xp.htm
    http://support.microsoft.com/?kbid=315237

    I may have to buy another network card and see if that solves the problem.

  5. #5
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    Quote Originally Posted by 23skidoo
    .....As I understand it, the problem is that the ack from the receiving side collides with the next packet from the sender. But I just know what Iread on the web. ....
    I hope someone that thinks this makes sense joins in. Yes, this was a problem on old 10 mbit coax systems, where everyone could talk on the wire at once. And manufactureres still need to play by the specs. But for 100BaseT without a hub (or even with a hub if only two computers are very active on the wire) collisions shouldn't be a problem - there is only one sender on the wire at any instant, so there is nothing for the packet to collide with. The first link you provided says that it collides with the ACK coming back, but 100BaseT transmits back on a different pair than it receives on, so there is no chance for a collision there. Most 100BaseT systems, in fact, are specified to run full duplex, meaning they are intended to transmit and receive down the different pairs at the same time.

    Have you tried the registry change given in the second link you posted?

    Maybe this is a problem that one of the adapters is only a half duplex adapter but the system is trying to run in full duplex mode and the hardware can't cut it. Shouldn't happen, because the hardware should negiatate a half duplex connection, but it's my best guess at the moment. You might be able to force Knoppix to work in half duplex mode (I don't think you have that much control in Windows, but if Knoppix forces it's side to run half duplex then whatever it's talking to will run half duplex also.) Try the mii-tool command to do this, either the -F switch and -r switch or the -A switch. See the man page for mii-tool for all of the options you will need with the switch to force half duplex (HD) operation. There will not be much of a speed penality here, as the acks are short, but there will be some since each side has to wait for the connection to "turn around".

    Also, you haven't said how your network is configured. If you have two computers networked directly together, then the half duplex trick might help, as it would force the XP box to run half duplex too. But if you are connecting through a switch or a router, the the switch/router also handshakes and decides if the connection runs full or half duplex (and at what speed). In such a case you could be talking half duplex to the switch/router with Knoppix and still have a full duplex connection between the switch/router to XP that might be the source of the problem. You might try connecting the Knoppix system directly to the XP system (you'll need a cross over cable or have at least one of the two nics "auto-sense" the wire - many routers and switches do this now but few NICs auto-sense. You mayl also need to set the IP addresses manually, as you'll likely have cut out a router that was providing DHCP services)

  6. #6
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    The machines are connected through a router. I've set to XP side to
    force full-duplex, the Knoppix side is in full duplex according to ethtool.

    The registry change mentioned seems to be speciific to the Intel
    EtherExpress 100B - which I believe is the card in the Knoppix machiine.


    BTW, your description of full-duplex, 100BaseT matches how I thought it
    worked too. However, I can't imagine an XP system using Ethernet over
    co-ax - so it must be a problem with newer networks also.

    I suppose I could buy a couple of 1000BaseT cards and a crossover cable ....
    the USB solution should have been almost as good. I'm worried that
    actually getting new network cards to work could be as hard as getting
    the USB solution to work. Installing NICs tends be either trivial or
    extremely difficult. Is there a well-supported-by-Knoppix. cheap gigabit card?

    2.3 GB transferred in 14.5 hours - only 15 GB left!

  7. #7
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    Quote Originally Posted by 23skidoo
    The registry change mentioned seems to be speciific to the Intel EtherExpress 100B - which I believe is the card in the Knoppix machiine.
    Considering the level the problem seems to be at, I wouldn't expect an XP registery change to have any effect if the suspected problem card is in the other computer.

    Quote Originally Posted by 23skidoo
    BTW, your description of full-duplex, 100BaseT matches how I thought it worked too. However, I can't imagine an XP system using Ethernet over co-ax - so it must be a problem with newer networks also.
    As long as XP has a driver for the card then it would support whatever type of media (coax vs twisted par) the card connects to. I'm reasonably certain that there are drivers in XP that will support old coax based cards (maybe even old thicknet based cards).

    Quote Originally Posted by 23skidoo
    I suppose I could buy a couple of 1000BaseT cards and a crossover cable ....
    Yea, maybe you could, but you introduce another issue; that being if Knoppix would support the gigabit card. It would seem that just the cross over cable might be enough, it gets the router's two NIC interfaces out of the way and so significantly changes things. Beyond that I might try swapping out the nics, one at a time (to determine which, if either, was the problem). I doubt that I would buy two gigabit NICS, since they will give you no real advantage when used with the router (I can see that if you don't have any spare NICs around you might want to buy one NIC and you might figure "I might as well buy a gigabit interface", but the price would have to be good to justify this, and as you mention you get into the issue of will that interface work with Knoppix. But if you got one that did work with Knoppix you could use it to replace either of the current interfaces to eliminate that as a source of the problem.

    And I'm still not buying the "collision" argument as being what the problem really is. You might even want to check around with some of your local contacts to see if anyone has access to protocol analizers and other related tools to let you get a good look at what is really happening on the wire.

    Another trick I might try (it sounds like you're trasnfering the files but can stop to do tests) would be to boot up that XP system with a Knoppix CD and see if you can do the transfers any faster that way (unfortunately, you should not write to a NTFS file system on the XP box with Knoppix, but I don't know if the partition you are saving this recovered data to is NTFS or something else).

    Beyond that I would consider changing anything I could to determine what the problem is. Is there another computer on the network, even if it doesn't have a free 17 gigs of space? Can you transfer to it any faster, or is it just as slow? Can you transfer between that third system and the XP box faster? (I'm trying to pin down where the bottle neck is). If you have another NIC, start changing out NICs. If you have another brand of router, try that. If you have a switch, plug that in one of the router ports and plug both computers into the switch (so they can still get dhcp but don't have to route their traffic through the router). Heck, I might even swap the cables at this point if I had spare cables, since damage to a cable or even a poorly constructed cable strikes me as more likely to cause this problem than collisions that can't really be happening.

  8. #8
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    can you exclude that the router acts as firewall, inspecting every file perhaps?

  9. #9
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    Your advice was good.... the problem is the XP machine. I was able to
    free up enough space on the sick box to rescue my data by copying some
    stuff to a laptop. That isolates the problem to 1 cable, 1 NIC, 1 configuration, or one switch port.

    I'll track down the problem with the XP machine as sood as I get the first
    machine fixed. It shouldn't be more than a day or two now.

    Thanks again

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