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Long Distance WDS

Discussion in 'Sveasoft Firmware' started by Zlatnia, Apr 15, 2005.

  1. Zlatnia

    Zlatnia Network Guru Member

    Hi guys! Any help will be good for me

    I'm spreading out my internet connection with 3 WRT54G routers set with WDS.

    I have the first router 1 mile away from the second one. It holds the Internet connection and it sends it to one wireless client half a mile away and to the second router. I have two wired clients connected to the second router. I have everything perfect with that pattern, Internet is like waterfall with no drops. The problem comes when I try to connect the 3rd one, despite of better signal between 2nd and 3rd router some signal drops has been observed. It's like 3 to 5 seconds good traffic flow followed by 1 second no traffic and it doesn't matter of the devices, I've tried with WAP54G instead of the 2nd WRT54G, it's still the same. The distance between the 2nd and the 3rd one is 1.5 miles. The signal strength between the 1st and 2nd one is aproximately rssi - 77, noise - 90 and between 2nd and 3rd one is rssi - 74, noise - 92. The schematic design is like:

    ADSL>>>WIN2K AS>>>WRT54G)))((((WRT54G>>>2PCs
    WUSB54G )))) ((((WRT54G>>>>2PCs

    I use Sveasoft Alchemy pre7 on all the routers, The routers on both ends are v2 and the middle one is v2.2. The signal strength is boosted to 90 mW.

    I have 2 15dB modified cantennas on the 1st router one pointing the client and the other to the 2nd router. On the 2nd I have 1 24dB grid parabolic antenna to the 1st router and 23 dB dish parabolic antena pointing the 3rd router on the 3rd ther's dish also.

    If you can help me, just help me.

    Thank you in advance!

    P.S. if you know if the advanced wireless settings are important for long distance connections
  2. Disman_ca

    Disman_ca Super Moderator Staff Member Member

    So this is how I see you WDS between 3 wrt54 units with an end point at router #1:

    router #1 WRT54 1 mile from #2 and 2.5 miles from #3
    router #2 WRT54 1 mile from #1 and 1.5 miles from #3
    router # 3 WRT54 2.5 miiles from #1 and 1.5 miles from #2

    Did you setup router #3 with a WDS MAC entry from #1? If you did this is probably your problem. By default the spanning tree protocol(STP) is trying to pass all traffice through both router #1 and #2. Router # 3 can not see router #1 (most likely) which would cause a performance issue. See the STP protocol tries to pass it through all WDS nodes you define on the router. If your router can not see another one, it will keep trying to re-initialize the path by restarting the WDS connections. Remove the WDS entry for number one and the performance should be better. If your doing testing, don't forget about the double transmit of any wireless clients connected to an AP. This in affect would cut the through put in half because the AP has to re-send all traffic from the wileless client.
  3. Zlatnia

    Zlatnia Network Guru Member

    Thank you for your help, but i didn't setup router #3 with the MAC #1. The only router which holds 2 WDS addresses is router #2, I don't know if it has something in common with your version becouse of the tries of #2 to pass all the trafc trough both of the routers. I'm going to try connect another router next to #2 and have 2 routers working on diferent channels instead of WDS working with 2 records.

    I realy wanted to do it with 1 router acting the repeater role.
  4. Zlatnia

    Zlatnia Network Guru Member

    So guys, the only way to work on long distance with WDS is to cut the chain and use 2 devices on every node between the very ends.

    If someone knows how to do it without cutting the chain, please let me know
  5. davidsonf

    davidsonf Network Guru Member


    So guys, the only way to work on long distance with WDS is to cut the chain and use 2 devices on every node between the very ends.

    If someone knows how to do it without cutting the chain, please let me know"

    Two antennas, each pointing at a different radios
    will not work.[fade]
  6. davidsonf

    davidsonf Network Guru Member

    Sorry, I clicked on the wrong button before completing the previous message.

    Two directional antennas, each pointing at a different distant radio will not work well.

    That is because the radio in the WRT54G has only one antenna actually connected at any given time. The radio switches periodically between them looking for incoming traffic, and will select the antenna with the best received signal. However, the transmit traffic goes out on the last antenna selected for receive! That means the initial transmit towards each of two different distant radios after data is received from the other will be on the wrong antenna in the arrangement you have.

    Because the wrong antenna in this case essentially amounts to totally losing the signal there is bound to be a very significant amount of negotiations between the two radios before the link is re-established and the data actually gets received.

    Then the whole proceedure starts again! You see it as long delays, and maybe even data dropouts.

    Basically if it won't work at all with one antenna removed, it will not be very good with a second antenna installed. Two high gain antennas only work when pointed in exactly the same direction.

    Also, with a single high gain antenna you want to put it on the connector closest to the WAN connector, not the one next to the power connector. That one has the shortest internal cable. With any of the third party firmware loads you'll also want to lock it to antenna 1 for both transmit and receive.
  7. gotamd

    gotamd Network Guru Member

    If that's true, couldn't you wire an access point to the second WRT and then point the antennas out to the third?
  8. Crashmaxed

    Crashmaxed Network Guru Member

    *DING* IDEA!

    After reading the part about how only 1 antenna is associated at any given time (which i've read something about that before as well) I got the same idea that gotamd did. Buy another WRT54G or use your WAP54G or whatever you have lying around or want to buy. Slap Alchemy pre7a on it and get ready to have some fun. Here is how it would be set up.
    Router 1)))) <---> ((((Router 2------Router 3)))) <---> ((((Router 4
    Router 1 will be direct connected to your internet connection. The antenna on router 1 will be facing router 2 at the physical location between the beginning and end of the chain. Router 1 will have Router 2's MAC for WDS and Router 2 will have Router 1's MAC for WDS. Router 2 and Router 3 will be wired together using a standard ethernet cable as they will be physically right next to each other. Router 3 will be hooked up to another antenna that is pointed at physical location 3, the end of the chain. Router 3 will have Router 4's MAC for WDS and Router 4 will have Router 3's MAC for WDS. In short terms. Have a WDS setup for Router 1 at site 1 and Router 2 at site 2. Also, have a 2nd WDS setup for Router 3 at site 2 and Router 4 at site 3. Then just wire Router 2 and 3 together and it should work. What this would effectively do is make it so each router 2 and 3 are connected to only one other AP and hence they don't have to share dishes :p
  9. Zlatnia

    Zlatnia Network Guru Member

    Re: *DING* IDEA!

    After many tries, #1)))(((#2---#3)))((((#4. As I said begore that is working, but pay attention if #2 and #3 are close to each other, they shoul differ in channels by 8 or 9 at least.

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