AP/Client connection negotiation process.

Discussion in 'Wireless Networking' started by quinnray@yahoo.co.uk, Aug 9, 2005.

  1. Guest

    HI,

    Can anyone point me to a doc which explains the initial connection
    process between an AP and client ?
    I had a look at some but they don't answer my questions.
    Something that addresses my questions below would be good.

    Thanks,
    Ray.

    When a client powers up, I guess it listens on each channel for an AP
    beacon, and then lists the available APs to the user ?
    When initiating a connection with an AP, I guess the client sends out
    a connection request to the AP ?
    This request might be a DHCP broadcast and must include MAC address,
    and SSID of AP ?
    What happens if 2 APs with the same SSID are operating on the same
    channel ?
    What happens if 2 clients assume the same IP and MAC (spoofing)?
    What determines if a connection is 'lost', and the client
    dis-associates itself with the AP ?
    , Aug 9, 2005
    #1
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  2. Pavel A. Guest

    <> wrote in message news:...
    >
    > Can anyone point me to a doc which explains the initial connection
    > process between an AP and client ?
    > I had a look at some but they don't answer my questions.


    Unless you tell what documents you've seen and why you remain unsatisfied
    it's difficult to recommend more...

    > Something that addresses my questions below would be good.
    >
    > Thanks,
    > Ray.
    >
    > When a client powers up, I guess it listens on each channel for an AP
    > beacon, and then lists the available APs to the user ?


    Depends on implementation (which depends on marketing requirements ;)
    Usually it scans; but it may start already locked to a certain channel
    or range of channels. Also, clent can be set up to do active scan
    for certain APs.

    > When initiating a connection with an AP, I guess the client sends out
    > a connection request to the AP ?


    Yes

    > This request might be a DHCP broadcast and must include MAC address,
    > and SSID of AP ?


    It is not related to DHCP but yes it includes MAC address and SSID.

    > What happens if 2 APs with the same SSID are operating on the same
    > channel ?


    Usually APs with same SSID belong to same network within organization.
    Since they have different MAC addresses, the client clearly sees that they are
    two different APs. Then the client decides which one is better (has stronger signal).
    It can be that this AP rejects connection (is too busy), then the client goes to next one
    with same SSID.
    If several APs with same SSID do not belong to same network or organization,
    then ... there's a problem :)

    > What happens if 2 clients assume the same IP and MAC (spoofing)?


    Bad things (but nothing crashes or explodes)

    > What determines if a connection is 'lost', and the client
    > dis-associates itself with the AP ?


    The WLAN device driver detects this and informs the OS and the controlling
    utility above it (which decides what to do next)

    Regards,
    --PA
    Pavel A., Aug 10, 2005
    #2
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  3. Guest

    Thanks for the reply Pavel,

    > Unless you tell what documents you've seen and why you remain unsatisfied
    > it's difficult to recommend more...

    I've mainly been looking at networking how-to's.
    I also had a look at some RFC's.
    It appears from the latter that this is quite a complex area.

    I'm interested to find out what goes on when 'associating' with an AP,
    and the initial signals sent out by the client.

    Cheers,
    Ray.
    , Aug 10, 2005
    #3
  4. Pavel A. Guest

    <> wrote in message news:...
    > Thanks for the reply Pavel,
    >
    >> Unless you tell what documents you've seen and why you remain unsatisfied
    >> it's difficult to recommend more...

    > I've mainly been looking at networking how-to's.
    > I also had a look at some RFC's.
    > It appears from the latter that this is quite a complex area.
    >
    > I'm interested to find out what goes on when 'associating' with an AP,
    > and the initial signals sent out by the client.


    You're right, wireless protocols are complex and still evolving.
    Unfortunately there is no simple way to learn them besides of... learning.

    Regards,
    --PA

    > Cheers,
    > Ray.
    >
    Pavel A., Aug 10, 2005
    #4
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