Use WAP54G to bridge separate subnet?

Discussion in 'Other Linksys Equipment' started by Todd, Mar 7, 2005.

  1. Todd

    Todd Network Guru Member

    Can anyone tell me if I can create a bridge between two separate subnets using WAP54Gs?

    For example, WAP54G number1 is on the network, whereas WAP54G2 is on the network. Can I create a wireless bridge between and or do I have to use the same subnet?

    Thanks in advance.
  2. Jogobo

    Jogobo Network Guru Member

    The WAP54G is an Access Point, not a Router! You can look at it like an uncabled hub or switch. So they have to be in the same subnet to work.

    Just my 2 €-cents.
  3. Todd

    Todd Network Guru Member

    I agree but the learn table on both wireless bridges will contain the MAC addresses of
    all the nodes for there subnet and all the nodes that are in the other
    subnet by way of the bridge that it is connected to. Also, When a wireless
    WDS link (unlike a wired/Ethernet bridge) is set up between the two bridges
    all four address fields in the MAC header are used and transmitted. They
    The MAC address of the sender
    The MAC address of the final destination
    The MAC address of the sending Bridge
    The MAC address of the receiving Bridge

    So, with this information won't the bridge in a fashion "route" a frame with
    a MAC address in the other subnet through the bridge because it knows by
    looking up in its learn table that the node at the destination MAC address
    is across the bridge?
  4. Jogobo

    Jogobo Network Guru Member

    In general you are right. And if your only goal is to connect the 2 networks it might work is you set up the IP of the bridge as default gateway in the according network.
    Let's call your network A and your network B. The bridges have the IP resp. Every PC in A has as default gateway, every PC in B has as default gateway. IP traffic in A meant for B is sent via wireless adapter in bridge A, IP traffic in B meant for A is sent via wireless adapter in bridge B.
    Trouble comes when A or B as an internet connection and the other network should use this connection too. Assuming that A has an internet connections would mean that non of the PCs in A could connect to the internet as all traffic not meant for 192.168.1.x is sent to bridge A (default gateway for this network) and cannot be delivered as there are no matching IPs and MAC adresses in B. So you have to set up a router in A which has a route for traffic to B and a route for all other traffic.

    In the end it's a matter of taste and network environment if the way you want to set up the network will work and with which configuration.

    Just my 2 €-cents.
  5. Todd

    Todd Network Guru Member

    Thanks for the info and the feedback. That makes complete sense in regards to configuring the gateway on the client to be the bridge but with a transparent bridge doesn't it appears to all hosts on the network as though it is not there. As far as the network layer (IP for example) is concerned, all networks connected by a bridge might as well be physically connected.

    The "default" action for a transparent bridge is to forward any received frame. So, I am wondering if that is the case with a transparent bridge if I would still have to configure the stations gateway to be their respective bridge??

    I appreciate that help.
  6. Jogobo

    Jogobo Network Guru Member

    AFAIK the transparent bridge only works within the same subnet. This is a matter of TCP/IP. A client PC needs a route to the destination if the destination is not within the same subnet. If client has no route to communication between the two will not happen.

    If client in subnet A want to communicate with client in subnet B there is no need of a specific route because the bridges work transparent, which means the clients do not need to know in which subnet the destination resides as the bridges take care of the transport from subnet A to B.

    2 WAPs in different networks cannot work as transparent bridges, 2 WAPs in different subnets can work as transparent bridges.

    Just my 2 €-cents.
  7. dabodude

    dabodude Network Guru Member

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