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WDS to share mp3 collection with neighbour? possible?

Discussion in 'General Discussion' started by luckmanl, Aug 31, 2005.

  1. luckmanl

    luckmanl Network Guru Member

    _______________INTERNET(A)_________________INTERNET(B)
    __________________||__________________________||
    PC(A)<-wireless->WRT54GS(A)--)))))))WDS(((((((--WRT54GS(B)<-wireless->PC(D)
    __________________||__________________________||
    _________________PC(B)______________________ PC(C)

    First of all, sorry for my bad drawing.
    I was thinking to share my mp3 and video collection (PC(A) and PC(B)) with my neighbour(PC(C) and PC(D)). do you think the above setting will work? I want PC(A) and PC(B) to use internet(A) connection and my neighbour's PC(C) and PC(D) will use internet(B) connection.

    What kind of setup i have to do with both routers?

    Thanks

    Luckman[align=justify:e32e9d1399][/align:e32e9d1399]
     
  2. 4Access

    4Access Network Guru Member

    Sure you could get your illustration to work. The biggest problem would be making sure the PCs use the correct internet connection if DHCP is enabled on the routers. The easiest solution would be to simply disable DHCP on the routers and statically configure the IP address on the clients making sure to specify the IP address of the router you want to use for internet access as the default gateway.

    Alternately because you'll be using custom firmware already to get the WDS link up you could also probably set the DHCP scope on both routers to only hand out 2 IP addresses and then configure DHCP reservations on the routers so they only hand out addresses to the proper clients.

    Finally you could configure different subnets for the two networks and then setup some static routes to route over the WDS link but that's more complicated so I'd suggest going with one of the 1st two ideas for simplicity.

    Good luck.
     
  3. luckmanl

    luckmanl Network Guru Member

    Thanks 4Access, I will give it a try on your first setup.

    Just curious, if i want to go for the 3rd setup, what is the advantage of it? Can u explain more details about the static routing thing?
    I believe me and my neighbour will be able to communicate to each other even we are on different subnet.

    Luckman
     
  4. 4Access

    4Access Network Guru Member

    The main advantage I can think of from a routed WDS connection is that you'd save some wireless bandwidth.

    By configuring everyone on the same subnet it means that all broadcast traffic from either side of the LAN will get sent across the WDS link. To prevent this you could for example configure your network to use 192.168.1.X addresses and your neighbor to use 192.168.2.X addresses. This (when combined with some additional configuration of the WDS link) would prevent broadcasts on the 192.168.1.X network from being sent across the WDS link to the 192.168.2.X network and vise versa.

    Note that this only saves you some bandwidth because to get WDS working you have to configure both routers to use the same wireless channel. This means every time router A transmits, router B is going to hear the transmission even if it is not intended for router B. Since only one device can transmit on a wireless channel at a time any broadcasts sent on network A will occupy the airwaves preventing router B from transmitting. The advantage comes in that the actual broadcast traffic from network A will be ignored by router B and won't get passed on to the network B clients which means they won't try to respond to the broadcast traffic. (That felt really wordy, hopefully it made sense... :unsure: )

    The disadvantage to setting up different subnets and a routed WDS connection is that unless you setup a WINS server or configure a LMHOSTS file (which I'll admit really isn't that hard) you will no longer be able to contact computers on the other subnet using their computer name or browse to them in My Network Places. (You'd have to use IP addresses instead.)

    The second disadvantage is that it is more complicated to configure and as best I can tell requires some of the work to be done from the command line. (At least I don't see a way to configure the necessary static route from the GUI although I'll admit I've never actually setup a routed WDS connection so may be missing something simple.)

    A routing table tells a device where to send data. When a computer needs to send data to an IP address that is on a different subnet it consults the routing table. The routing table tells the computer who to send the data to so that it will get passed along to the desired destination. If there is not an explicit entry in the routing table telling the computer where to send the data, the data gets sent to the default gateway. (The default gateway is the last entry in the routing table.)

    Now, by default your computer has its default gateway set to the IP address of your router. Your router in turn has its default gateway set to whatever was assigned by your ISP. If you don't setup a static route when using a routed WDS configuration the following will happen:

    You (IP 192.168.1.100) try to contact your friend's computer which has IP address 192.168.2.100. Your computer sends the packet to your router since that's your computer's default gateway. The router receives the packet and consults its routing table to determine what to do with the packet. Not finding an entry telling it what to do with packets destined for the 192.168.2.X subnet your router passes the packet along to its default gateway which is some router on the internet owned by your ISP.

    Configuring a static route on your router will tell it that when any packets arrive destined for the 192.168.2.X subnet that they should be sent across the WDS link. Make sense? :thumb:
     

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