problems with 2 ethernet LANS joined by wireless network bridge

Discussion in 'Wireless Networking' started by Guest, Jan 7, 2005.

  1. Guest

    Guest Guest

    A friend and I have wired lans at home with 2 and 5 pcs respectively. we
    want to connect the 2 lan together. Currently, he has a Gigabyte
    AP11g(802.11g) access point connected to his lan with an external high gain
    antenna. His ip addresses are and for the pcs and for the AP. the subnet mask we have used is On
    my side, I have converted a pc to perform "routing" functions. It has a
    100Mbps ethernet card connected to my hub and a MSI PC54G 802.11g wifi card,
    also with an external antenna. We get excellent signal between the two
    points. My ip addresses range from to with
    subnet for the other pcs. The routing pc has the ethernet
    adpapter with and the wifi adapter with both with
    subnet Before i bridge both networks work perfectly on
    their own and i can access any pc from any other on its respective network.
    To bridge the 2 networks, I use the Win XP network bridge with an ip of and subnet I have had to force the wifi card
    into promiscuous mode using "netsh bridge adapter x" to make the bridge work
    and i have edited the registry to enable ip forwarding in the tcpip services

    Now the problem - As soon as i add both networks to the bridge, I am able
    to see all the others pcs from any wired pc and i can even copy files across,
    but after a while(5 to 10 minutes) the "view workgroup computers" option
    takes very long to load and i cannot see any computers other than the ones
    directly connected via a hub. I can ping all the machines from the routing
    pc and get a response but the other pcs can only ping each other until the
    workgourp pcs arent viewable again. Another odd thing that happens is in
    quake 3 - if, say he starts a multiplayer game on his side, i can see the
    game on all my machines but i cannot get into it except for the routing pc,
    hereas if i start the game on the routing pc alltheother pcs can enter the

    How can I have the network wroking porperly so that a pc can always connect
    to another as long as the ap and the routing pc are switched on?

    Are my ip address and subnet mask assignments incorrect? are there any other
    settings i have forgotten to change?
    Guest, Jan 7, 2005
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  2. Blizard,

    I believe that you want to make two separate networks and join them together
    with an IP router. I'll explain to you how the configuration should
    appear. This configuration would not work with bridging, so going forward
    we are not using a bridge, but rather IP routes. Below I'll explain why.
    Further on, I'll explain the short fix to make this work with your bridge.
    You can decide which you really want to do.

    The first problem that I have noted in the configuration is the use of a
    1-bit subnet mask. is not really a valid subnet, and is not really a valid subnet mask. . However, this may work. I
    would recommend using a subnet mask of This will give you addresses as:, 67, on the first subnet on the neighboring network, with the
    router being, following convention.
    Now, the second network can operate with the following:
    IP addresses:, 131, with the router's address being, as above.

    Now, my question is: why bridge? Why not just create routes between the two
    networks? Bridging is slow, because it is not optimized for all layer 2
    (IP, etc.) situations, and using the wireless link will be more costly and
    slow. If these two networks are indeed separate, bridging them would make
    them slower, while routing does not impeed the ability of one network to
    function. For example: ARP. ARP resolves IP addresses into MAC addresses.
    Bridging makes the network twice as large, and so therefore, ARPing has
    twice as much cost. ARPing does not happen across distinct IP networks, per
    definition, so adding a new subnet does not make ARPing slower. Do you see
    my point? Not everything will be slower, but bridging does have it's costs.
    And it has it's conveniences as well.
    The big convenience will be this ability to "browse" the local network and
    "see" all of the computers in a LAN Workgroup. I think that is useful, so
    in the end you may want to bridge after all. If you can live without that,
    the best option is to use names and create a LMHOSTS file with the addresses
    of each machine. You seem like someone who knows what is going on, so I'll
    leave that decision to you.

    So, on the XP machine for routing, the routes to the networks will already
    be created, but you need to enable routing between the interfaces.;en-us;315236&Product=winxp
    This is not an official recomendation that you change your registry. Please
    back-up your system before making registry changes.

    Now to the short answer. If you still want to bridge, and not set this up
    at the IP level, the solution is to eliminate your subnet, and make the
    machines part of one big network.
    IP address: ..
    Give each machine an address and set up the bridge- it should work this
    Brian Wehrle [MSFT], Jan 10, 2005
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