Cisco Cisco 4402 Wireless LAN Controller Folheto
Upgrading to 4.1.185.0 or Later: What to Change or Verify?
1. From the CLI, check:
show advanced [802.11b|802.11a] txpower
The new default value is -70dbm. If it has been modified, revert to the defaults since this new value has
been shown to be optimal under a range of conditions. This value needs to be the same on all the
controllers in an RF group. Remember to save the configuration after making changes.
been shown to be optimal under a range of conditions. This value needs to be the same on all the
controllers in an RF group. Remember to save the configuration after making changes.
In order to change this value, issue this command:
config advanced [802.11b|802.11a] tx-power-control-thresh 70
2. From the CLI, check:
show advanced [802.11a|802.11b] profile global
The results should be:
802.11b Global coverage threshold.............. 12 dB for 802.11b
802.11a Global coverage threshold.............. 16 dB for 802.11a
802.11a Global coverage threshold.............. 16 dB for 802.11a
If the results are different, then you use these commands:
config advanced 802.11b profile coverage global 12
config advanced 802.11a profile coverage global 16
config advanced 802.11a profile coverage global 16
The client SNR cut-off parameter that determines if the client is in violation, and if the Coverage Hole
algorithm’s mitigation kicks in, called Coverage should be reverted back to the defaults for optimum
results.
algorithm’s mitigation kicks in, called Coverage should be reverted back to the defaults for optimum
results.
3. From the CLI, check:
show load-balancing
The default state of load-balancing is now Disabled. If enabled, the default window is now 5. This is the
amount of clients that need to be associated to a radio before load-balancing upon association will take
place. Load-balancing can be very useful in a high density client environment, and the use of this
feature must be a decision from the administrator so client association and distribution behavior is
understood.
amount of clients that need to be associated to a radio before load-balancing upon association will take
place. Load-balancing can be very useful in a high density client environment, and the use of this
feature must be a decision from the administrator so client association and distribution behavior is
understood.
Radio Resource Management: Tips and Best Practices
RF Grouping and Tx Power Threshold
TIPS:
Ensure that the Tx power threshold is configured the same on all controllers that share the RF Group
Name.
Name.
In versions earlier than 4.1.185.0, the default Tx power threshold was -65dBM, but this threshold value
of -65dBm can be too “hot” for most deployments. Better results have been observed with this threshold
set between -68dBm and -75dBm. With Version 4.1.185.0, the default Tx power threshold is now -
70dBm. With 4.1.185.0 or later, it is strongly advised that users change the Tx power threshold to -70
and verify if the results are satisfactory. This is a strong recommendation since various RRM
enhancements can cause your current setting to be sub-optimal now.
of -65dBm can be too “hot” for most deployments. Better results have been observed with this threshold
set between -68dBm and -75dBm. With Version 4.1.185.0, the default Tx power threshold is now -
70dBm. With 4.1.185.0 or later, it is strongly advised that users change the Tx power threshold to -70
and verify if the results are satisfactory. This is a strong recommendation since various RRM
enhancements can cause your current setting to be sub-optimal now.
WHY:
The RF Group Name is an ASCII string configured per wireless LAN controller (WLC). The grouping algorithm
elects the RF Group leader that, in turn, calculates the Transmit Power Control (TPC) and Dynamic Channel
Assignment (DCA) for the entire RF Group. The exception is Coverage Hole algorithm (CHA), which is run per
WLC. Because RF Grouping is dynamic, and the algorithm runs at 600-second intervals by default, there might
be an instance where new neighbors are heard (or existing neighbors are no longer heard). This causes a
change in the RF Group that could result in the election of a new Leader (for one or multiple logical RF
Groups). At this instance, the Tx Power Threshold of the new group leader is used in the TPC algorithm. If the
value of this threshold is inconsistent across multiple controllers that share the same RF Group Name, this can
result in discrepancies in resultant Tx power levels when the TPC is run.
elects the RF Group leader that, in turn, calculates the Transmit Power Control (TPC) and Dynamic Channel
Assignment (DCA) for the entire RF Group. The exception is Coverage Hole algorithm (CHA), which is run per
WLC. Because RF Grouping is dynamic, and the algorithm runs at 600-second intervals by default, there might
be an instance where new neighbors are heard (or existing neighbors are no longer heard). This causes a
change in the RF Group that could result in the election of a new Leader (for one or multiple logical RF
Groups). At this instance, the Tx Power Threshold of the new group leader is used in the TPC algorithm. If the
value of this threshold is inconsistent across multiple controllers that share the same RF Group Name, this can
result in discrepancies in resultant Tx power levels when the TPC is run.
Coverage Profile and Client SNR Cut-Off
TIP: