Does any 802.11g network only downshift to "b" when a 802.11b device is actively connected?

[mshan]

I've got an Apple Airport Extreme (gigabit ethernet with n wireless) connected to my cable modem.

Most of my devices are g, but I do have one old laptop whose wireless is a Linksys WUSB11 v 2.8 802.11b wireless usb adapter.

Does my whole network only downshift to b when this 802.11b device is actively connected, AND does it automatically revert back to "g" when that device is no longer detected?

 

[spidey07]

Only if the b client is associated to the access point does it operate in backward compatibility mode lowering service to all clients. The AP will operate at G modulation/speeds as long as there is no B client associated with it.

It's not that the entire carrier shifts to 11 meg vs 54, it's that the 11 meg client takes a lot more of the carrier and time than the G clients. It's been a while so forgive the possible misinformation...OFDM rates (greater than 11 Mbs) are 802.11G only. As soon as a B client associates the AP will change it's modulation of the carrier to support the B client. This change in modulation lowers overall throughput of G clients even if associated at top data rate of 54 Mbs.

 

[mshan]

So, if I turn off that specific computer, should a wireless router automatically shift back up to "g" mode?

Or will it stay "b" until I restart the router?

 

[spidey07]

Per specification it is supposed to go back to G mode. Best practice is to force 802.11g that way the AP doesn't even bother responding to B clients and changing the modulation and slowing down. All it takes is a single B client in your cell to slow you down.