3Com 3CRWX120695A, 3CRWX440095A Configuration Manual page 153

Configuring MAP Access Points 153
Changing the preamble length value affects only the support advertised
by the radio. Regardless of the preamble length setting (short or long),
an 802.11b/g radio accepts and can generate 802.11b/g frames with
either short or long preambles.
If any client associated with an 802.11b/g radio uses long preambles for
unicast traffic, the MAP access point still accepts frames with short
preambles but does not transmit any frames with short preambles. This
change also occurs if the access point overhears a beacon from an
802.11b/g radio on another access point that indicates the radio has
clients that require long preambles.
The default preamble length value is short. This command does not
apply to 802.11a radios.
To change the preamble length advertised by 802.11b/g radios, use the
following command:
set radio-profile name preamble-length {long | short}
To configure 802.11b/g radios that use the radio profile rp_long to
advertise support for long preambles instead of short preambles, type the
following command:
WX1200# set radio-profile rp_long preamble-length long
success: change accepted.
Resetting a Radio Profile Parameter to its Default Value
To reset a radio profile parameter to its default value, use the following
command:
clear radio-profile name parameter
The parameter can be one of the radio profile parameters listed in
Table 11 on page 134.
Make sure you specify the radio profile parameter you want to reset. If
you do not specify a parameter, MSS deletes the entire profile from the
configuration.
All radios that use this profile must be disabled before you can delete the
profile. If you specify a parameter, the setting for the parameter is reset
to its default value. The settings of the other parameters are unchanged
and the radio profile remains in the configuration. If you do not specify a
parameter, the entire radio profile is deleted from the configuration.