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AP/Client connection negotiation process.

 
 
quinnray@yahoo.co.uk
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      08-09-2005
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 ?

 
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Pavel A.
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      08-10-2005
<(E-Mail Removed)> wrote in message news:(E-Mail Removed) ups.com...
>
> 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


 
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quinnray@yahoo.co.uk
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      08-10-2005
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.

 
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Pavel A.
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      08-10-2005
<(E-Mail Removed)> wrote in message news:(E-Mail Removed) oups.com...
> 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.
>



 
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