AP with 802.11 G Vs clients with 802.11b

[andrea.soc]

hi

i've got more access point 1200 series with he 802.11g but the client are 802.11b . Can the client 802.11b connect at the AP with 802.11 G ? Now i don't resolve this problem anche the client 802.11b connect only with the ap 1200 series with 802.11b

Thanks for all

[willskei]

G is backwards compatible and your B clients should have no problem connecting. Make sure you set the correct Data rates within the G radio so your B clients can connect. Keep in mind your AP will now be in protection mode.

[scottmac · Accepted solution]

The 802.11b clients can connect with the 802.11g APs -if- you have compatible data rates configured on the AP. If you set the AP to use the "Default" rates (versus "Throughput" or "Distance") in the WebGUI, it should work OK.

Having a mix of 'b' and 'g' clients will reduce the speed somewhat for the 'g' clients. This is because of the "Protection" mechanism used by the AP to let the 'g' clients know that there are 'b' clients on the same system.

'b' and 'g' use the same frequencies & channels, but they use different encoding / modulation schemes and can't directly see each other.

The protection process and mode switching reduce the AP's throughput.

Good Luck

Scott

[andrea.soc]

thank you very much Scott. now work it ! !

[vault_dweller]

802.11G can work in OFDM with CCK without 802.11B support, i think this can increase WLAN coverage... How can i enable this on my 1200 APs but -without- 802.11B clients?

[scottmac]

If you disable the "b" data rates, you've pretty much blocked "b" clients.

They may be able to respond / attempt association (that all happens at either one or two mbps for either "b" or "g" ... long or short preambles), but since they dont have compatible data rates, they can never connect.

Good Luck

Scott

[vault_dweller]

> If you disable the "b" data rates, you've pretty much blocked "b" clients.

A-ha... As i can understand i must disable 1.0, 2.0, 5.5 and 11.0 speed's.

"To set the 2.4-GHz, 802.11g radio to serve only 802.11g client devices, set any Orthogonal Frequency Division Multiplexing (OFDM) data rate (6, 9, 12, 18, 24, 36, 48, 54) to Basic."(c) Cisco IOS Software Configuration Guide for Cisco Aironet Access Points 12.3(7)JA

This the same thing as entering `speed throughput ofdm`? Command disables all 802.11B data rates as you recommend.

> They may be able to respond / attempt association (that all happens at either one or two mbps for either "b" or "g" ... long or short preambles), but since they dont have compatible data rates, they can never connect.

I know... But, AFAIK, when 802.11G AP "see" 802.11B client in his coverage area AP "downgrades" to 802.11B to allow this client associacion. Your recommedation prevents this, i'm right? Try to understand me, many years i used damn D-Link (my boss love it) but one day i sad "Cisco or on no any kind wireless :E" and now i have dosens AP-1200 with my many questions... All want now i want - is set "G-only" (in dlink's terms) like function...

Thank you

P.S. Sorry for my english