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Well,I have an AP supporting 802.11b,802.11g and Mix-mode.When the AP is setup to work in 11g ONLY mode, my 11b ONLY client cannot associate with the AP.However, if the AP is in 11b ONLY mode, the 11g ONLY client is able to associate with the AP. What are the factors affecting this? Is it beacons, basic rates or supported rates? Isn't the 802.11g backward compatible with 802.11b? Need your opinions on this.
Thanks a lot.

Hi Raul:

An ERP (802.11g) station supports both the HR/DSSS (802.11b) rates and the OFDM (802.11a) rates. (Although ERP and OFDM stations both use the "OFDM" rates they use different frequencies and so are not interoperable.)

An ERP access point (AP) configured for "802.11b only" mode turns off its support for the OFDM rates and only supports HR/DSSS rates. An ERP client station can still connect but will do so only with its HR/DSSS rates. This is coordinated by the rate information in beacons.

I hope this helps. Thanks. /criss

Thanks for the clear explanation.

Thanks for the clear explanation.

Hi Criss.
Yet another question.
Is it necessary for ERP access point configured in "802.11b only" to allow 802.11g stations get associated?
I have two ERP access points configured in "802.11b mode".
Only one of them allow 802.11g stations get connected.
I supposed the one denying 802.11g stations supports only DSSS instead of HR/DSSS.
Am I right?

Hi Raul of Taiwan:

IEEE ERP (802.11g) clients are physically capable of associating with access points built with DSSS (802.11 clause 15), HR/DSSS (802.11b), or ERP (802.11g) hardware. Configuration details may make them incompatible.

"802.11b only" is vendor proprietary but probably means that the access point does not offer the so-called OFDM rates. This does not prevent ERP client hardware from associating and operating with the non-OFDM rates of HR/DSSS.

An example of an incompatible configuration is a client security configuration that requires a cipher suite not offered by an access point.

I hope this helps. Thanks. /criss

So does it means the ERP stations should connect with both of the APs(no security misconfiguration)?
Many thanks!

Hi Raul of Taiwan:

Yes, ERP client stations should have no problem associating to ERP access points configured for "802.11b Only".

If an ERP client does not, then look for something restrictive in its client configuration. Security policy is but one example.

I hope this helps. Thanks. /criss