Multiple WAPs

Archived from groups: alt.internet.wireless (More info?)

I'm trying to plan out a wireless network for a building, including multiple
WAPs. I want users to be able to roam between access points seamlessly.
Maybe I'm just being dense, but I can't seem to find any information on
exactly how to set this up. Google hasn't helped much.

What I think I'm seeing is that you can connect multiple WAPs to a single
wired router. The WAPs should be configured with the same SSID and
encryption, but the broadcast channels would have to be different (if
they're in range of each other). This would allow some sort of
technological magic to happen between the WAPs and wireless devices, and
roaming would occur without the user noticing.

Am I on the right track here?

Thanks!

ADY
--
adyoung (at) sbcglobal (dot) net
7 answers Last reply
More about multiple waps
  1. Archived from groups: alt.internet.wireless (More info?)

    On Tue, 12 Oct 2004 17:27:04 -0500, MousePad spoketh

    >I'm trying to plan out a wireless network for a building, including multiple
    >WAPs. I want users to be able to roam between access points seamlessly.
    >Maybe I'm just being dense, but I can't seem to find any information on
    >exactly how to set this up. Google hasn't helped much.
    >
    >What I think I'm seeing is that you can connect multiple WAPs to a single
    >wired router. The WAPs should be configured with the same SSID and
    >encryption, but the broadcast channels would have to be different (if
    >they're in range of each other). This would allow some sort of
    >technological magic to happen between the WAPs and wireless devices, and
    >roaming would occur without the user noticing.
    >
    >Am I on the right track here?
    >
    >Thanks!
    >
    >ADY

    Yes.

    Lars M. Hansen
    http://www.hansenonline.net
    (replace 'badnews' with 'news' in e-mail address)
  2. Archived from groups: alt.internet.wireless (More info?)

    On Tue, 12 Oct 2004 17:27:04 -0500, "MousePad"
    <adyoungentirely.too.much.junk.mail.in.my.mailbox@sbcglobal.net>
    wrote:

    >I'm trying to plan out a wireless network for a building, including multiple
    >WAPs. I want users to be able to roam between access points seamlessly.

    So does everyone else. Dream on.

    >Maybe I'm just being dense, but I can't seem to find any information on
    >exactly how to set this up. Google hasn't helped much.

    There's plenty available with Google. Search for "wireless roaming".
    The problem is that you'll find very little commodity hardware that
    claims to do it seamlessly. There are no current specifications for
    how to do roaming and how to handle the handoff.

    IEEE 802.1f defines the best practices for wireless roaming.
    http://standards.ieee.org/getieee802/download/802.11F-2003.pdf

    802.1r is the proposed fast wireless roaming standard. I don't this
    it's available for general consumption quite yet.

    See article:
    http://www.winnetmag.com/Windows/Article/ArticleID/23294/23294.html
    There's a short list of vendors in the above article that provide
    proprietary wireless roaming solutions.

    >What I think I'm seeing is that you can connect multiple WAPs to a single
    >wired router. The WAPs should be configured with the same SSID and
    >encryption, but the broadcast channels would have to be different (if
    >they're in range of each other).

    Correct. Use the same SSID so that Windoze XP and other client will
    automatically switch to the "best" access point signal if you select a
    particular SSID as the "prefered" SSID. Actually, I don't think you
    have to select preferred as once associated with an SSID, Windoze XP
    SP2 will try to stay associated. The non-overlapping channels (1, 6,
    and 11) are to prevent RF interference between WAP's.

    >This would allow some sort of
    >technological magic to happen between the WAPs and wireless devices, and
    >roaming would occur without the user noticing.

    Magic? Here's the problem. Your Windoze laptop client radio connects
    to an access point, an associates an SSID with the access points BSSID
    (same as MAC address of the wireless access point). Now, you move to
    a different location, the signal evaporates, and you pickup another
    access point with the same SSID. Just one problem, different MAC
    address. Are you gonna give up on the old MAC address and switch to
    the new address? Sure, but after how long a delay? Meanwhile, the
    original access point still has your client radios MAC address in its
    bridging table, and is furiously trying to get your attention. Your
    laptop is still trying to talk to the old access point.

    Eventually they will both give up, but if it takes too long, you may
    find yourself with two (or more) access points trying to get your
    attention. Meanwhile, the switch in the router is going nuts as your
    client radios MAC address is seen moving from port to port. At least
    this can be done fairly quickly. Anyways, lots of other things can go
    wrong during roaming.

    The usual solution is to use very short DHCP lease times, force a
    disconnect when the client radio switches to a different access point,
    and deliver a new IP address to the client via DHCP. This will drop a
    connection in progress, trash a VPN connection, and ruin a VoIP phone
    call, but will not really affect normal email and web browsing (other
    than a small delay).

    >Am I on the right track here?

    Yeah, sorta. If you can tolerate disconnects and re-assigned IP
    addresses when switching WAP's, then you're done. Just about anything
    with control over the DHCP lease time will work. If you absolutely
    want seamless roaming, you'll need to find a proprietary solution.
    Plan on emptying your bank account.

    Due to lack of detail on your proposed system, I don't wanna offer a
    specific hardware recommendation. However, you might wanna look into
    a "wireless switch" such as:
    http://www.symbol.com/products/wireless/ws_5000_brochure.html
    which are intelligent switches, with brain dead radios attached. With
    all the brains in the central box, port switching and roaming is much
    easier. See the section in the above URL for some detail on roaming.


    --
    # Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
    # 831.336.2558 voice http://www.LearnByDestroying.com
    # jeffl@comix.santa-cruz.ca.us
    # 831.421.6491 digital_pager jeffl@cruzio.com AE6KS
  3. Archived from groups: alt.internet.wireless (More info?)

    "Jeff Liebermann" <jeffl@comix.santa-cruz.ca.us> wrote in message
    news:qaepm012kq58nv6nols1c7kc5clg76efln@4ax.com...

    >>Am I on the right track here?
    >
    > Yeah, sorta. If you can tolerate disconnects and re-assigned IP
    > addresses when switching WAP's, then you're done. Just about anything
    > with control over the DHCP lease time will work. If you absolutely
    > want seamless roaming, you'll need to find a proprietary solution.
    > Plan on emptying your bank account.

    There's a lot of good information there. Thank you very much.

    Since I don't have money to burn, I'm thinking that I need to stick with
    basic WAPs and a switch. I'll keep the number of access points to a
    minimum. One per floor will likely be enough. In practice, I don't think
    there will be a whole lot of roaming around the building. Most users will
    stay in one area.

    I can upgrade in a year or two, once roaming standards are more complete and
    equipment is more cost-effective.

    ADY
    --
    adyoung (at) sbcglobal (dot) net
  4. Archived from groups: alt.internet.wireless (More info?)

    On Wed, 13 Oct 2004 09:59:02 -0500, "MousePad"
    <adyoungentirely.too.much.junk.mail.in.my.mailbox@sbcglobal.net>
    wrote:

    >Since I don't have money to burn, I'm thinking that I need to stick with
    >basic WAPs and a switch. I'll keep the number of access points to a
    >minimum. One per floor will likely be enough. In practice, I don't think
    >there will be a whole lot of roaming around the building. Most users will
    >stay in one area.

    That will work. No need for anything special. If you can run CAT5
    between WAP's, you're fine. I forgot to mention WDS (Wireless
    Distribution Something). Effectively, each access point becomes a
    repeater. Bandwidth is cut in half every time you have to store and
    forward some packets, but it completely eliminates the CAT5 run
    between floors. I don't like this method, but it does work.

    >I can upgrade in a year or two, once roaming standards are more complete and
    >equipment is more cost-effective.

    Upgrade? I don't think so. Most manufacturers do not support
    products past their useful market lifetime. In a year or two, you
    won't be able to find much firmware for any of the newer acronyms.
    Getting WPA support for older client cards is almost impossible. If
    you wanna go with the bleeding edge and possibly preserve your
    hardware investment, methinks that the 3rd party open source firmware
    for the WRT54GS series is the best bet. The other alternative is to
    build a central switch using a Linux box and use dumb 802.11 access
    points.

    --
    Jeff Liebermann jeffl@comix.santa-cruz.ca.us
    150 Felker St #D http://www.LearnByDestroying.com
    Santa Cruz CA 95060 AE6KS 831-336-2558
  5. Archived from groups: alt.internet.wireless (More info?)

    "Jeff Liebermann" <jeffl@comix.santa-cruz.ca.us> wrote in message
    news:9iuqm05uo6sgv1a5q4ofo552gf635j8hg2@4ax.com...

    > That will work. No need for anything special. If you can run CAT5
    > between WAP's, you're fine. I forgot to mention WDS (Wireless
    > Distribution Something). Effectively, each access point becomes a
    > repeater. Bandwidth is cut in half every time you have to store and
    > forward some packets, but it completely eliminates the CAT5 run
    > between floors. I don't like this method, but it does work.

    The building's already wired with CAT5. That won't be a problem.

    > Upgrade? I don't think so. Most manufacturers do not support
    > products past their useful market lifetime. In a year or two, you
    > won't be able to find much firmware for any of the newer acronyms.
    > Getting WPA support for older client cards is almost impossible. If
    > you wanna go with the bleeding edge and possibly preserve your
    > hardware investment, methinks that the 3rd party open source firmware
    > for the WRT54GS series is the best bet. The other alternative is to
    > build a central switch using a Linux box and use dumb 802.11 access
    > points.

    By "upgrade" I meant "replace." /:)

    ADY
    --
    adyoung (at) sbcglobal (dot) net
  6. Archived from groups: alt.internet.wireless (More info?)

    MousePad wrote:
    > "Jeff Liebermann" <jeffl@comix.santa-cruz.ca.us> wrote in message
    > news:qaepm012kq58nv6nols1c7kc5clg76efln@4ax.com...
    >
    >
    >>>Am I on the right track here?
    >>
    >>Yeah, sorta. If you can tolerate disconnects and re-assigned IP
    >>addresses when switching WAP's, then you're done. Just about anything
    >>with control over the DHCP lease time will work. If you absolutely
    >>want seamless roaming, you'll need to find a proprietary solution.
    >>Plan on emptying your bank account.
    >
    >
    > There's a lot of good information there. Thank you very much.
    >
    > Since I don't have money to burn, I'm thinking that I need to stick with
    > basic WAPs and a switch. I'll keep the number of access points to a
    > minimum. One per floor will likely be enough. In practice, I don't think
    > there will be a whole lot of roaming around the building. Most users will
    > stay in one area.
    >
    > I can upgrade in a year or two, once roaming standards are more complete and
    > equipment is more cost-effective.
    >
    > ADY

    FWIW, I agree w/ Jeff's points in principle, in practice I've set up
    many-a-sites as you've described with cisco aps, all set w/ same ssid
    and have had no problem roaming between. granted nobody was doing
    anything like VoIP calls, etc... but i think most
    non-super-latency-sensitive tcp traffic will be fine.

    good thing you have the cat5 ran, repeating is a nightmare. Although
    there are products out there now that handle the issue _VERY_ well with
    multiple radios. check out http://www.strixsystems.com.

    Jeremy
  7. Archived from groups: alt.internet.wireless (More info?)

    On Wed, 13 Oct 2004 05:50:00 GMT, in alt.internet.wireless , Jeff
    Liebermann <jeffl@comix.santa-cruz.ca.us> wrote:

    >On Tue, 12 Oct 2004 17:27:04 -0500, "MousePad"
    ><adyoungentirely.too.much.junk.mail.in.my.mailbox@sbcglobal.net>
    >wrote:
    >
    >>I'm trying to plan out a wireless network for a building, including multiple
    >>WAPs. I want users to be able to roam between access points seamlessly.
    >
    >So does everyone else. Dream on.

    Maybe I have some weird setup, but when I walk between my 11G AP at the
    front of my house and my 11B one at the rear, WinXP apparently seamlessly
    shifts from one AP to the other when the signal strength of the first
    vanishes.

    It might depend on what you expect - for me, its good enough to have the
    same IP address on each AP, and for the laptop user not to notice any
    disconnection.
    --
    Mark McIntyre
    CLC FAQ <http://www.eskimo.com/~scs/C-faq/top.html>
    CLC readme: <http://www.ungerhu.com/jxh/clc.welcome.txt>


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