Specifications

12 General
Customer buys new APs for the n-radio and keeps the old a/b/g APs intact. Running dual
5.0 GHz radios
Customer Has Already Invested in 802.11n Dual Band APs and Has Replaced All Old APs
in the Same Position
In installations that support 802.11n from the beginning, or for a WLAN that has been forklifted to
support 802.11n, the following scenario may be relevant:
b/g a Comment
-
Old AP
Data (legacy)
20 MHz only
New AP
Data (HT) DFS
Old AP
Voice -(no HT),non-
DFS, 20 MHz only.
This will allow the voice traffic to run on the non-DFS
(Dynamic Frequency Selection) channels and the data
traffic to run on the DFS channels. See also,
Section ,
“802.11a Radar Protection, Dynamic Frequency Selec-
tion (DFS)”, on page -13.
b/g/n a/n Comment
Legacy mode Legacy mode Customer runs the APs in legacy mode.
See above for possible combinations since in this case 802.11n
features are not turned on.
Voice +
data (legacy)
20 MHz only
Mixed mode
Data (HT),
40 MHz
Greenfield
The a/n radio is set for Greenfield mode only. Only HT clients ac-
cepted and no 20 MHz support.
Laptops may benefit from all enhancements in the 802.11n stan-
dard like MIMO, dual bandwidth channels etc.
Data (HT)
20 MHz only
Mixed mode
Voice (no HT)
20 MHz only
Mixed mode
Keep all data clients on the g/n radio. Laptops will benefit from
all 802.11n enhancements except the use of double bandwidth
channels, since the amount of channels will be dramatically re
-
duced.
Note: The handset does not support either Greenfield or 40 MHz
modes.
Legacy data Voice 20 MHz +
Data (HT)
40 MHz
non-DFS
Mixed mode
or
Voice 20 MHz +
Data (HT)
20 MHz
Mixed mode
Voice and data are both on the a/n radio.
Using 40 MHZ channels for data will reduce the amount of chan-
nels possible by half for the handset.
Best combination is to move voice over to a/n.