This visualization shows what
format of 802.11 frames (also called packets)
is being used in the given WLAN area. Wi-Fi networks use three
This is a legacy frame format used by 802.11 a/b/g
||HT-mixed: This is a frame format introduced
in the 802.11n standard. It uses a protection mechanism that allows
802.11n devices to coexist with legacy 802.11 a/b/g devices,
including those that do not belong to your WLAN.
||HT-Greenfield: This is a frame format
introduced in the 802.11n standard, too. Unlike in HT-mixed mode,
devices operating in Greenfield mode assume that there are no
legacy 802.11 a/b/g stations around using the same or adjacent
channels. 802.11 a/b/g devices cannot communicate with Greenfield
devices. Rather, their packets will collide, causing problems for
This is the latest frame format introduced in the 802.11ac
standard. This format is used in the 5 GHz band only. It uses a
protection mechanism that allows 802.11ac devices to coexist with
legacy 802.11a and 5 GHz 802.11n devices, including those that do
not belong to your WLAN.
Frame format is shown for the
AP that has the strongest signal in the given map area among the
APs selected for analysis. This mimics the roaming behavior of
client adapters that connected to the strongest AP. While other
audible APs may use other frame formats, a typical adapter will
connect to the AP with the strongest signal. You can deselect one
or several of the selected APs to see frame formats for less strong
Among the three pre-802.11ac
frame formats, the best throughput is provided by HT-Greenfield. In
HT-mixed format, protection mechanisms that ensure coexistence with
legacy equipment reduce throughput. However, it should be noted
that as per the 802.11n standard, support for HT-Greenfield frame
format is not mandatory, and currently, few APs support it. In the
realm of 802.11ac, VHT is the only available format.
Double-clicking on the Frame
Format legend on the status bar allows you to configure the color
scheme and change its value range.
If you do not see the frame
formats that you expect to see, the following solutions are
your AP configuration. If you are using 802.11n equipment, see if
Greenfield mode is available, if HT-Greenfield frame format is what
you want. Note that some APs have the “802.11n only” option, but
this option does not necessarily mean that HT-Greenfield frame
format will be used. Rather, switching this option on may simply
disable legacy data rates.
AP's ability to send frames in HT-Greenfield format depends on the
wireless environment. A Greenfield-enabled AP may fall back to
HT-mixed format in some situations (e.g., when a non-802.11n device
connects to the AP or when other non-Greenfield APs are detected
nearby). Because of the changing environment, the site survey
results regarding the frame format may change from time to time.
Perform site surveys regularly.
are using legacy 802.11 a/b/g equipment, consider upgrading to
802.11n or 802.11ac.
||Remember that VHT is not available in the
2.4 GHz band.