Changing DCA and TxPowerLevelAssignment Interval

Answered Question
Apr 28th, 2008
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Hi Folks, on a WLC i like to change the default DCA and PowerLevelAssignment Interval from 600sec to a much longer Interval. Any Idea how to do that? I found nothing about that in Documentation/GUI/CLI... Rgrds, Michael

Correct Answer by bcolvin about 9 years 2 months ago

With release 4.1.185 you can now modifiy the DCA behavior to lessen the impact of a rolling Channel change.


first limit the available channels to 1,6,11


second through the command line you can determine when DCA starts and how ofter it runs. the folling is from the release document.


New DCA CLI Commands

These new CLI commands have been added to configure the dynamic channel allocation (DCA)

algorithm:

• To control the DCA sensitivity with respect to changes in the environment, enter this command:

config advanced {802.11a | 802.11b} channel dca sensitivity {low | medium | high}

The DCA algorithm determines whether to make a channel change based on how much better a new

channel would be for the radio with the worst DCA metric in the radio band. The DCA metric is

comprised of noise, interference, channel load, and overlapping neighbors (other radios on the same

channel). Previously, a channel change would occur if another channel was 5 dBm better than the

current channel of the radio with the worst DCA metric. This new command allows you to control

how sensitive the DCA algorithm is to environmental changes, such as signal, load, noise, and

interference, when determining whether to change channels. Table 2 shows the three available DCA

sensitivity levels.

For example, if the radio with the worst DCA metric in the 2.4-GHz band has a metric of -60 dBm

on its current channel and the DCA algorithm finds that the metric would be -80 dBm on another

channel (which is an improvement of 20 dBm), the DCA algorithm would change the channel if the

DCA sensitivity is set to high or medium. It would not change the channel if the sensitivity is set to

low.

• To define the time when DCA starts, enter this command:

config advanced {802.11a | 802.11b} channel dca anchor-time hour

where hour is an hour in the day from 0 to 23 (12:00 a.m. to 11:00 p.m.).

• Previously, the DCA algorithm ran every 10 minutes. To now define how often DCA runs, enter this

command:

config advanced {802.11a | 802.11b} channel dca interval value

where value is 0, 1, 2, 3, 4, 6, 8, 12, or 24. 0 equals 10 minutes and is the default value. The rest of

the values represent hours. So if you specify a value of 8, DCA would run every 8 hours.

For example, if you specify an anchor time of 0 and a DCA interval of 12, the DCA algorithm would

run at 12:00 a.m. and 12:00 p.m. every day.

Note You can view the configured DCA sensitivity, anchor-time, and interval on the 802.11a (or

802.11b/g) Global Parameters > Auto RF page on the controller GUI. However, you can

configure these values only from the controller CLI.

Table 2 DCA Sensitivity Levels

DCA Sensitivity

Level Description

2.4-GHz DCA Sensitivity

Threshold (dB)

5-GHz DCA Sensitivity

Threshold (dB)

High High sensitivity to

environmental changes

5 5

Medium (default) Moderate sensitivity to

environmental changes

15 20

Low Low sensitivity to

environmental changes

30 35


Apparently RRM will still run on its own schedule.



There is light


Bill



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Overall Rating: 4 (4 ratings)
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ericgarnel Mon, 04/28/2008 - 05:52
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It is under wireless| 802.11.. under RRM

MICHAEL SCHROEDER Mon, 04/28/2008 - 06:15
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Hi Eric, under RRM/AutoRF i can choose AutomaticInterval/OnDemand or OFF for both DCA and TxPower, but i cant change the Length of the Interval from 600sec to a longer one, right? Wher can i change the Interval Time or is it not possible?

Rob Huffman Mon, 04/28/2008 - 06:44
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Hi Michael,


Sadly this number (600 seconds/10 minutes) is not able to be changed;


Transmit Power Control Algorithm


The TPC algorithm, run at a fixed ten minute interval by default, is used by the RF Group Leader to determine the APs' RF proximities and adjust each band's transmit power level lower to limit excessive cell overlap and co-channel interference.



Each AP reports an RSSI-ordered list of all neighboring APs. Provided an AP has three or more neighboring APs, the RF Group Leader applies the TPC algorithm on a per-band, per-AP basis in order to adjust AP power transmit levels downward such that the third loudest neighbor AP is heard at a signal level of -65dBm (default value) or lower.


Power changes are only made when the third loudest neighbor of a given AP is heard at a signal level higher than the default value of -65 dBm.


Power Level Assignment Method-The TPC algorithm can be configured in one of three ways:


Automatic-This is the default configuration. When RRM is enabled, the TPC algorithm runs every ten minutes (600 seconds) and, if necessary, power setting changes will be made at this interval. ****This is a display-only field and cannot be modified.****


From this excellent doc;


http://www.cisco.com/en/US/tech/tk722/tk809/technologies_tech_note09186a008072c759.shtml#tpca


Hope this helps!

Rob

MICHAEL SCHROEDER Mon, 04/28/2008 - 07:13
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Hi Rob, thx for your detailed explanation. I know this doc, and it helped me to understand what DCA and TPC are doing in detail. Anyway, i have to live with 10min Intervals. Rgrds, Michael

MICHAEL SCHROEDER Mon, 04/28/2008 - 07:13
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Hi Rob, thx for your detailed explanation. I know this doc, and it helped me to understand what DCA and TPC are doing in detail. Anyway, i have to live with 10min Intervals. Rgrds, Michael

Correct Answer
bcolvin Tue, 04/29/2008 - 08:45
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With release 4.1.185 you can now modifiy the DCA behavior to lessen the impact of a rolling Channel change.


first limit the available channels to 1,6,11


second through the command line you can determine when DCA starts and how ofter it runs. the folling is from the release document.


New DCA CLI Commands

These new CLI commands have been added to configure the dynamic channel allocation (DCA)

algorithm:

• To control the DCA sensitivity with respect to changes in the environment, enter this command:

config advanced {802.11a | 802.11b} channel dca sensitivity {low | medium | high}

The DCA algorithm determines whether to make a channel change based on how much better a new

channel would be for the radio with the worst DCA metric in the radio band. The DCA metric is

comprised of noise, interference, channel load, and overlapping neighbors (other radios on the same

channel). Previously, a channel change would occur if another channel was 5 dBm better than the

current channel of the radio with the worst DCA metric. This new command allows you to control

how sensitive the DCA algorithm is to environmental changes, such as signal, load, noise, and

interference, when determining whether to change channels. Table 2 shows the three available DCA

sensitivity levels.

For example, if the radio with the worst DCA metric in the 2.4-GHz band has a metric of -60 dBm

on its current channel and the DCA algorithm finds that the metric would be -80 dBm on another

channel (which is an improvement of 20 dBm), the DCA algorithm would change the channel if the

DCA sensitivity is set to high or medium. It would not change the channel if the sensitivity is set to

low.

• To define the time when DCA starts, enter this command:

config advanced {802.11a | 802.11b} channel dca anchor-time hour

where hour is an hour in the day from 0 to 23 (12:00 a.m. to 11:00 p.m.).

• Previously, the DCA algorithm ran every 10 minutes. To now define how often DCA runs, enter this

command:

config advanced {802.11a | 802.11b} channel dca interval value

where value is 0, 1, 2, 3, 4, 6, 8, 12, or 24. 0 equals 10 minutes and is the default value. The rest of

the values represent hours. So if you specify a value of 8, DCA would run every 8 hours.

For example, if you specify an anchor time of 0 and a DCA interval of 12, the DCA algorithm would

run at 12:00 a.m. and 12:00 p.m. every day.

Note You can view the configured DCA sensitivity, anchor-time, and interval on the 802.11a (or

802.11b/g) Global Parameters > Auto RF page on the controller GUI. However, you can

configure these values only from the controller CLI.

Table 2 DCA Sensitivity Levels

DCA Sensitivity

Level Description

2.4-GHz DCA Sensitivity

Threshold (dB)

5-GHz DCA Sensitivity

Threshold (dB)

High High sensitivity to

environmental changes

5 5

Medium (default) Moderate sensitivity to

environmental changes

15 20

Low Low sensitivity to

environmental changes

30 35


Apparently RRM will still run on its own schedule.



There is light


Bill



MICHAEL SCHROEDER Tue, 04/29/2008 - 09:56
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Hi Bill, absolutely what i wants to know, thx a lot.


I've seen the light...


Broght Rgrds, Michael

Bill, in your example you cite that a -60dBm DCA metric is worse than a -80dBm metric. Is this how its interpreted (as a "negative" interference value, not a signal strength value), or should this be the reverse?


>>For example, if the radio with the worst DCA metric in the 2.4-GHz band has a metric of -60 dBm on its current channel and the DCA algorithm finds that the metric would be -80 dBm on another channel (which is an improvement of 20 dBm), the DCA algorithm would change the channel if the DCA sensitivity is set to high or medium. It would not change the channel if the sensitivity is set to

low.


bcolvin Thu, 05/01/2008 - 08:37
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Bruce


the numbers you are referencing were cut and pasted from the Cisco release document.


what i believe they are trying to say is when your neighbour on the same channel is to loud -60 you will move to another channel in a quieter neighbor hood loudest neighbour is -80 and the senitivity setting determins wat the delta is to trigger the change.


did not expect this quetion.


Better


Bill

Rob Huffman Thu, 05/01/2008 - 05:32
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Hey Bill,


Nice work here my friend! 5 points for this excellent update.


Take care,

Rob

bcolvin Thu, 05/01/2008 - 08:39
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Rob


Thanks for the points, always appreciated


keep up the good work


Bill

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