Disable Short Gi

The following scenario shows how to disable the short guard interval, which forces the configured network to use the long preamble instead of the default short guard.

Disable Short Guard Interval

Description

In this example, a WLAN interface will be created on top of the 5GHz radio module in access-point mode. Then, the short guard interval will be disabled be means of the disable-short-gi command.

Scenario

Warning

Note that the long preamble is considered a legacy (meaning it should be only used when very old devices are present,since performance decreases by around 10%).

Step 1: Run command configure at DUT0 and expect this output: Step 2: Run command delete interfaces wlan at DUT0 and expect this output:

Show output

Nothing to delete (the specified node does not exist)

Step 3: Run command delete controllers wlan at DUT0 and expect this output:

Show output

Nothing to delete (the specified node does not exist)

Step 4: Run command commit at DUT0 and expect this output: Step 5: Set the following configuration in DUT0:

set controllers wlan installation indoor
set controllers wlan radios wifi0 band 5GHz
set controllers wlan radios wifi0 bandwidth 80MHz
set controllers wlan radios wifi0 channel 36
set controllers wlan radios wifi0 mode 802.11ac
set controllers wlan radios wifi0 mode 802.11ax
set controllers wlan radios wifi0 mode 802.11n
set interfaces bridge br0
set interfaces wlan wlan1 bridge-group bridge br0
set interfaces wlan wlan1 phy wifi0
set interfaces wlan wlan1 type access-point security akm none
set interfaces wlan wlan1 type access-point ssid network_5GHz
set system login user admin authentication encrypted-password '$6$GSjsCj8gHLv$/VcqU6FLi6CT2Oxn0MJQ2C2tqnRDrYKNF8HIYWJp68nvXvPdFccDsT04.WtigUONbKYrgKg8d6rEs8PjljMkH0'

Step 6: Configure the MON device to listen for packets on channel 36 for 10s seconds discarding all packets not sent by DUT0. Then, apply the following filter to the captured traffic:

wlan.ht.capabilities.short40 == 1 && wlan.vht.capabilities.short80 == 1

At least one packet with the provided criteria must be present.

Step 7: Modify the following configuration lines in DUT0:

set controllers wlan radios wifi0 disable-short-gi

Step 8: Configure the MON device to listen for packets on channel 36 for 10s seconds discarding all packets not sent by DUT0. Then, apply the following filter to the captured traffic:

wlan.ht.capabilities.short40 == 0 && wlan.vht.capabilities.short80 == 0

At least one packet with the provided criteria must be present.

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