Wireless Access

I have the following network setup:

   - Aruba controller 3600 - centralized - OS6.1.3.9

   - At the branches:

             - Router that does line aggregation (minimum 2 ISP lines)

             - 10 to 20 RAP93 (each location has a separate AP group)

What I noticed is that we have APx that is near APy and they are set to same channel with power levels that create interfereance.

The only thing that I noticed is that APx is using ISP1 and APy is using APy - is this confusing ARM and thinks that they are in separate locations or the fact that both of them are in the same group should already enforce that they are at the same location?

As long as APx sees the APy as a neighbor it shouldnt be on the same channel. Could you turn-off client-aware from Arm-profile temporarily to see if the AP can switch over to a better channel. Because when client-aware is enabled and clients are actively talking to the AP, it wont be swithing channel.

Thank you.

I did an show ap monitor ap-list ap-name APx and it's not seeing APy broadcasting but it sees APz that is on the same side as APy but further - APz is on the same ISP as APx. (That has no logic).

I forgt to mentione the AP's are on a staight line :

      APx   .....   APy ........ APz (something like this they would look on the map).

We've seen this in our high density deployments (250+ AP with 3000+ clients).

Some things to look at:

What power level are the APs at currently?  Do they all settle to the minimum power level allowed?  You might want to reduce the max and min levels.  Don't just reduce the minimum because it can cause a 'super' AP where clients see that signal strength and attach to it. It is entirely possible the intf_index calculated by ARM is very high and the same channel may be the best channel based on the ARM algorithms.  We had this issue until we lowered the max/min power levels down to 12/9 or so.

I don't like to put APs in a line down the hallway (if that is what you have) or where they can all 'see' each other without walls in between.  Realize that ARM is taking measurements and these APs see each other with strong signals.  This can cause them to turn down their power level as well as increase interference.  To add insult to injury, clients are inside the rooms on the other side of the wall(s) which means they are seeing a reduced power level.  Lowering the power level on the APs in the hallways will help with ARM channels/power but clients will have reduced performance because they are getting less signal strength.

For every deployment possible, I put APs in rooms with the users and keep APs from 'seeing' each other directly.  This can require a few more APs but the performance of the entire system is improved.

By the way, are these 2.4ghz or 5ghz channels?  2.4ghz is much more likely to see this issue than 5ghz (number of channels, etc.).

The issue is still very strange in the fact that APx sees APz but not APy that is in between and causing the interference to APx.

The power levels are manually set at max because of the ammount of AP's the client was willing to install.

I would expect ARM to work if they AP would detect the other AP in the WiFi space - But the AP doesn't see the SSID from the APy - that will cause ARM on APx to do NOTHING.

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@Constantin wrote:

The issue is still very strange in the fact that APx sees APz but not APy that is in between and causing the interference to APx.

The power levels are manually set at max because of the ammount of AP's the client was willing to install.

I would expect ARM to work if they AP would detect the other AP in the WiFi space - But the AP doesn't see the SSID from the APy - that will cause ARM on APx to do NOTHING.

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It is a more involved than "there are two access points next to each other and they should be on different channels".  Please take a look at the ARM supplement document here:  http://support.arubanetworks.com/DOCUMENTATION/tabid/77/DMXModule/512/Command/Core_Download/Default.aspx?EntryId=2569

Skip to the part with "ARM Troubleshooting" and "Too Many APs on the same channel" to determine why that access point is on that channel to give you more information.

1) Client aware is enabled for us (thus even if we have the intf_indx biger than ARM Free Channel Index default = 25 the AP wouldn't change channel)

2) The noise level was way above ARM Noise Threshold default = 75

3) We had the error rate under ARM Error Rate Threshold default = 50

4) APx ch1 was not able to see either with "show ap monitor ap-list ap-name APx" or "show ap arm neighbors ap-name APx" - the SSID broadcasted by APy ch1  but able to see APz ch6. But was able to see other SSID's on ch1.

5) We cheched the ap arm scanin-times and saw that ARM is passing through all 2.4Ghz and 5Ghz.

I hope this will help.

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@Constantin wrote:

1) Client aware is enabled for us (thus even if we have the intf_indx biger than ARM Free Channel Index default = 25 the AP wouldn't change channel)

2) The noise level was way above ARM Noise Threshold default = 75

3) We had the error rate under ARM Error Rate Threshold default = 50

4) APx ch1 was not able to see either with "show ap monitor ap-list ap-name APx" or "show ap arm neighbors ap-name APx" - the SSID broadcasted by APy ch1  but able to see APz ch6. But was able to see other SSID's on ch1.

5) We cheched the ap arm scanin-times and saw that ARM is passing through all 2.4Ghz and 5Ghz.

 

I hope this will help.

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Thanks for the additional information.  The output from the command "show ap arm rf-summary ap-name <ap-name>" contains the data that ultimately determines if an access point should change channels or not.  This factors in all data, not just access points on the controller that it can see.  Please examine the output of that command to see why it would not change channels.