Direct connection via multiple Ethernet adaptors

Discussion in 'Home Networking' started by Robert Sneddon, Dec 14, 2008.

  1. I have two PCs, both connected via an unmanaged 10/100 switch to the
    flat's broadband router. I'd like to fit a Gigabit Ethernet adapter card
    to both PCs and connect them directly with a cable, to do backups and
    other fast operations just between the two of them. I'm running Windows
    2000 on both machines.

    I can't find information about doing something like this; I want to
    keep access to the broadband connection for both machines while having
    this fast direct connection running at the same time, with file shares.
    Is it possible at all?
    Robert Sneddon, Dec 14, 2008
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  2. Robert Sneddon

    John Weston Guest

    Why not simply replace your 10/100 switch with a 10/100/1000 switch?
    Then you have the future option of adding NAS, Media server or other
    computer to your LAN at Gb speeds - and you'll only need one LAN
    interface and driver SW in your computers.

    It would be possible to do what you want by allocating different IP
    addresses to each interface. You'll also need to do the necessary
    routing in the PC, because you would have two routes that can reach the
    same destination - but that's all extra SW overhead for each computer...
    John Weston, Dec 14, 2008
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  3. Cost, basically. I've got a USB GigE adaptor kicking around (from a
    failed experiment trying to get a wired Ethernet connection working on a
    PDA), and a PCI GigE adaptor for the other machine would cost about 6-8
    quid. Adding a GigE switch to the network would cost me at least 25 quid
    for a no-name cheapo and 35-40 quid for something like a Netgear. What
    I've got hooked up right now is working OK, I'd just like to add an
    extra fast connection between these two machines as cheaply as possible.
    The rest of the network is running OK at 100Mbps capability.
    Chunks of the wiring in this place are Cat5, not Cat5e or Cat6, so a
    flat-wide upgrade to usable GigE would require a rewire and I'm not
    wanting to go down that route just yet. Any NAS would be done "locally",
    in one room, and we don't have a TV set here to stream "media" to.
    Streaming Radio 4 LW, well maybe but that doesn't really require GigE
    But that would be too easy.
    That's what I'm not sure about, how to set up routing so that a given
    fileshare will be allocated to the GigE link and not to the primary
    10/100 connection that also carries the broadband and other things like
    the printer share. I don't want to mess up my existing configuration
    with random experimentation.
    Robert Sneddon, Dec 14, 2008
  4. Robert Sneddon

    Stephen Guest

    install the adaptors and use a 4 pair straight thru cable between

    give the new adaptors IP addresses on a different subnet.

    if that is all you did then w2k will make its own mind about which way
    to connect.

    Then you can bias the choice depending on interface costs, where you
    point the default route for internet etc.
    if backup etc is all just file sharing then you need to set up in the
    applications, but if not you can vary the bindings of protocols
    against each adaptor - for example microsoft file sharing on the old
    one but not on the new one to limit which way that protocol goes.

    if your backup allows an IP address for the remote machine, then pick
    the one on the interface / subnet you want.
    Stephen, Dec 14, 2008
  5. Robert Sneddon

    Rob Morley Guest

    There may be a neater solution, but here's a quick and dirty fix that
    should work I think (I'd try it but I don't have any Windows machines

    Say the router is netmask Set the gigabit
    NICs in the two machines to and, both with
    netmask and run

    route add -p mask if

    on the machine whose address is

    route add -p mask if

    on the machine whose address is

    What this does:

    route add -p : set a persistent route to override the default gateway
    (which is your router)

    192.168.1/2.0 mask : the network you're adding a route to
    (the network that the other machine's gigabit card is on)

    192.168.1/2.1 : the gateway to that network (actually the machine you
    want to connect to, but that's OK because everything it receives will
    be for itself, and it knows what to do with that)

    if 192.168.1/2.1 : the interface to use to connect to that gateway
    (forces each machine to use its gigabit card to connect to that network)

    If there are firewalls running on the machines you may need to open them
    up to the other networks.
    Rob Morley, Dec 14, 2008
  6. I just managed to get hold of a couple of cheap Realtek 8169 GigE cards
    to actually try this out.
    That's what I've got set up now, connected to the existing 10/100
    switch and both machines, IP addresses and
    mask This is working perfectly well, with both machines
    having access to the internet and file shares available over the 10/100
    link in both directions.
    For reasons of numbering consistency I've actually set them up as:

    Main: IP mask

    Backup: IP mask
    I tried this:

    route add -p mask if

    on the main machine (

    which, as I understand it should have set up a permanent route between
    the 192.168.1.* subnet via the backup machine's interface (
    to the main machine ( I got back an error:

    "The route addition failed: Either the interface index is wrong or the
    gateway does not lie on the same network as the interface. Check the IP
    Address Table for the machine."

    When I look up the help for "route" under W2K (route /?) It says the
    "if" parameter is an index, like 2 or 3 rather than a specific IP
    address as in your example.


    route ADD MASK METRIC 3 IF 2

    I'm not sure where I can find this interface index number via either
    the DOS ipconfig command or the GUI network device configuration.

    I've set up the interface cards, loaded MS Update drivers (they're both
    Realtek 8169 cards), connected them directly with a Cat6 cable and I can
    ping them both ways successfully from either machine.

    Assuming I can get these persistent routes to work how do I then go on
    to create specific file shares that will use these routes and not the
    default 10/100 speed connections already in place?
    Robert Sneddon, Dec 20, 2008
  7. Robert Sneddon

    Rob Morley Guest

    Looks like this script from the W2k Resource Kit should do it:
    I think you'll just need to address them by IP address rather than
    machine name e.g. \\\backups once they're set up, BICBW.
    Rob Morley, Dec 22, 2008
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