Automatic roaming

Discussion in 'Wireless Networks' started by Rich Roller, Dec 5, 2005.

  1. Rich Roller

    Rich Roller Guest

    Automatic roaming seems a generally desirable feature of WiFi... to have
    your laptop automatically detect when there's a stronger Access Point within
    range and transparently switch to that better/stronger AP.

    Myself and my customers have noticed that laptops with built-in radios,
    using Windows XP to manage their wireless connections, do NOT do this. In
    order to re-associate with a nearer/better/stronger AP they have to
    stop/start the wireless radio.

    My questions are:

    1. Is automatic roaming controlled by the wireless client, e.g. XP, or
    rather by the physical/network layer, e.g. the wireless radio/adapter?

    2. If it's the hardware, does anyone know if/how one might get a laptop,
    e.g. IBM Thinkpad, with built-in Intel PRO/Wireless 2200 B/G to do automatic
    roaming?

    TIA,

    Rich
     
    Rich Roller, Dec 5, 2005
    #1
    1. Advertisements

  2. Rich Roller

    MadDog Guest

    I'm curious as to why you think auto roaming is a good idea. What if the
    stronger network is one you have no access to ?? You'd have to manually
    connect back to the network you do have access to anyway.

    MD
     
    MadDog, Dec 5, 2005
    #2
    1. Advertisements

  3. Rich Roller

    Rich Roller Guest

    Yeah, I forgot to mention that I'm talking about roaming to the SAME WLAN,
    the SAME SSID, just a different AP. In other words, you take your laptop to
    another part of your company's offices and you want it to find the best
    AP/signal available within that same network.

    -Rich
     
    Rich Roller, Dec 5, 2005
    #3
  4. Rich Roller

    Ryan Younger Guest

    XP's WZC does do this. Setup an ESS with different AP's and XP will
    automatically roam to the AP with the strongest signal.


    --
    All the best,

    Ryan Younger.
    http://spaces.msn.com/members/wirelessnetworking/ - Ryan's Wireless
    Networking Weblog

     
    Ryan Younger, Dec 6, 2005
    #4
  5. Rich Roller

    Rich Roller Guest

    From what I've seen in the XP interface there is a choice to enter an SSID
    of a WLAN and that's it. There are no settings/controls related to specific
    AP's or for roaming between AP's within a given SSID network.

    Is there some more advanced version of the Windows client (WZC?) that has
    more settings/controls?

    From my testing (and a newsgroup support engineer from MS has confirmed
    this) Windows will NOT automatically roam between different AP's on the same
    SSID/WLAN unless you stop/start radio, or disconnect/reconnect.

    In the past when I used Cisco wireless cards w/ Cisco client, this happened
    beautifully. We are bemused by the fact that the built-in Intel radio plus
    WZC doesn't do this for us.

    Have you had different results with auto roaming?

    -Rich
     
    Rich Roller, Dec 6, 2005
    #5
  6. Rich Roller

    Cleve S. Guest

    My Dell Latitude D610, WinXP SP2, using WZC and not the Intel PROSet
    Wireless app. seems to do it fine. I have 3 G AP's, a Cisco & 2 Linksys.
    They're all WPA with a pre-shared key. They have the SSID hidden and
    they're all on the same channel.

    It doesn't seem to release the distant AP as fast as it might. It seems to
    look for a new AP once the existing signal gets down to around fair, even if
    the new signal is excellent.

    Cleve S.
     
    Cleve S., Dec 9, 2005
    #6
  7. Rich Roller

    Bill Steiner Guest

    When you have multiple access points, with signals that over lap, is it
    better to set them to different channels or keep them all on the same
    channel?

    Thanks,

    Bill
     
    Bill Steiner, Dec 11, 2005
    #7
  8. Rich Roller

    Cleve S. Guest

    Bill,

    I'm not certain, but I remember seeing in the Linksys instructions to keep
    them on the same channel. I've had it both ways, didn't see much
    difference. We really don't roam here, we just can't get wire to some
    areas.

    Cleve S.
     
    Cleve S., Dec 11, 2005
    #8
  9. Rich Roller

    Jason Guest

    Rich,

    I'm glad you posted this because it was just a coincidence I was trying to
    setup the same thing at home and was searching the newsgroup to find a
    solution. I have a Linksys wireless router downstairs and added a Microsoft
    wireless router as an access point. I wanted to do this because the signal
    from the router in the basement would get weak in certain areas upstairs.

    The Compaq Presario I had with a wireless card would automatically recognize
    the stronger signal among the router and access point and automatically
    switch as I walked around the house. However, I also have an IBM Thinkpad
    (running XP) with the built-in Intel PRO/Wireless 2200 B/G and it would not
    switch as I walked around. I did figure out how to get it to work.

    Go to Device Manager
    Go to Properties for the Intel PRO/Wireless device
    Click on the Advanced tab
    Click on the "Roaming Aggressiveness" Property
    Mine was set to "Lowest" which, according to the Description, it will not
    switch unless there is significant signal degradation.

    I changed mine to one level below Highest and now it automatically switches
    as I roam around.

    -Jason
     
    Jason, Dec 17, 2005
    #9
  10. Rich Roller

    Rich Roller Guest

    Bill's right. You should not have overlapping AP's using the same channel.
    If you have 3 AP's you can use channels 1, 6 & 11 which will ensure that
    there is no interference or contention between the AP's. -Rich
     
    Rich Roller, Dec 28, 2005
    #10
  11. Rich Roller

    Rich Roller Guest

    Jason,

    Thanks very much for posting what may just be my solution! (I had heard
    somewhere else that roaming was more a function of the adapter than of XP or
    WZC)

    *EXCEPT* that my Thinkpad+Intel2200BG does not have the Advanced property
    "Roaming Aggressiveness". :-(

    Perhaps I need to upgrade the Intel driver??

    If I go into Properties of Intel PRO/Wireless 2200BG it says:
    HW ver 1.1.3
    Driver ver 8.1.0.28
    NCPA ver 8.1.0.35
    And there are only 4 properties:
    Ad Hoc Transmit Power
    Mixed Mode Protection
    Power Management
    Wireless Mode

    I suspect that you show more than 4 properties, and have different versions
    than I do... correct?

    Thanks again. (I feel like I have a line of pursuit now)

    -Rich
     
    Rich Roller, Dec 28, 2005
    #11
  12. Rich Roller

    Rich Roller Guest

    Jason,

    Yes, I confirmed that the later driver (9.x) adds the "Roaming
    Aggressiveness" property. Haven't had a chance to test laptop in a multi-AP
    environment yet, but I'm optimistic based on what you said.

    I had been thinking of upgrading the driver but your post got me to actually
    do it. So thanks again!!

    -Rich
     
    Rich Roller, Dec 28, 2005
    #12
  13. Rich Roller

    Rich Roller Guest

    Update: A few weeks ago I did test this and indeed the "Roaming
    Aggressiveness" feature, set to 4 or 5, made a big difference in the laptops
    re-associating to the strongest AP when it comes into range.

    Thanks again!

    -Rich
     
    Rich Roller, Jan 17, 2006
    #13
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.