Cisco Aironet Ordering Playbook – #WirelessTuesday Special Edition

 

Please Note:  I updated this video in response to some great feedback I got.  Keep those comments coming!

Download the presentation here.

Resource Links

ROI & Refresh Tools

Products

 

Is My WLAN Controller Healthy (or, how do I program my stereo’s equalizer)?

old-stereo

When I was young, maybe early teens, I remember having a friend who’s dad was super proud of his stereo system.  I remember it had a stereophonic hifi turntable, 2 cassette decks (for dubbing), and it was even hooked to his reel-to-reel. I remember thinking of how powerful it was… I mean, LOOK at all those buttons, knobs, and sliders!  We got in trouble once because we messed with the equalizer.  He had just recently got it sounding like he wanted it and we… well… undid his work.

Now later in life I learned that just about no one knew how to properly set an equalizer, and this included my friend’s dad (nor did he know it should be tuned for each type of music).  He just did the best he could, trying to decipher the instructions, and taking best guesses.  Take this equalizer in the picture… it has 10 sliders from 31 Hz (sub bass) on the left to 16 Khz (high tones) on the right.  Now this picture will do nothing but make a muddy mix, the highs and mids louder and pulling down the low-mid sounds… so yeah… but that’s not the point. (But if you want a good reference for setting your EQ check this out.)

My point is there are a lot of buttons, knobs, and sliders, and they all work together.  For some of them, if they’re just a little off, it could change the sound in a major way.  Just like on an enterprise class wireless system.  Am I right?

So now then how do I configure my equalizer Cisco Wireless LAN Controller?  Great question.  Glad you asked.

When I log on to a controller I want to first see if it’s healthy.  Go through each row of the table below to see what I tend to look for in determining health.  This is not an exhaustive list, but it’s a solid start.  If your WLAN is “healthy” based on this list and you’re still having trouble, then we’d start troubleshooting.

(Please note that as I begin to use this as a reference I may find ways to make it better.  Be sure to check back later for updates.  Use the comment section below if you have ideas, too.)

What I’m Looking For Resources
Monitor Top Tab
What version of code is the controller running? I like to see the controller running the latest MD release for whatever code train it’s running. This is often referred to as a Maintenance Release or MR.

Be sure to check release notes before upgrading code, noting support for the equipment that is deployed.

There are (typically) no reasons to use any code earlier than 7.6 in a production environment.

What is the uptime? Is there a reasonable explanation for when it last rebooted?  It should never reboot on it’s own.
Are any 2.4 or 5 GHz radios listed as Down and you’re not sure why? Since there are only 3 usable channels in 2.4 GHz and 12-20+ in 5 GHz it’s not uncommon to see some 2.4 GHz radios turned off so AP’s can be packed in tighter to accommodate a lot of clients.
Do you have any Excluded or Disabled Clients? It is recommended to keep the client exclusion policies turned on. Clients can be excluded for:

Excessive 802.11 Association or Authentication failures

Excessive 802.1x Authentication failures

Duplicate IP (referenced as Identity Theft or IP Reuse)

Excessive Web Authentication failures

Any disabled clients were done manually.

Is there an excessive amount of Active Rogue AP’s? Where there is not a firm line that indicates there are “too many” rogue AP’s, however if the number of active rogue AP’s is more than 50% of the total number of AP’s, it’d be a good idea to understand why and possibly take mitigating actions.
Are there any Active Rogue Clients? A “Rogue AP” is one that your AP’s can hear that is not part of your own network. In fact a rogue AP may not be rogue at all, it may simply be an AP used by a neighbor for their own use.  A “Rouge Client” is a client device that is connected to a Rogue AP.
Anything “interesting” in the Most Recent Traps? Look for major events like AP Disassociated, Failed to…, Signature attack, Potential denial of service, temperature too high, etc.
MONITOR -> Access Points -> Radios -> 802.11a/n/ac Look for failures in:

Load Profile (failed means more than 20 clients)

Noise Profile (failed means over -70 dBm)

Interference Profile (failed means more than 25%)

Coverage Profile (failed means a detected coverage hole)

A failure does not necessarily indicate a systemic problem, only an indicator a configured threshold has been crossed.
If you notice a lot of failures in the same area you may want to investigate.

MONITOR -> Access Points -> Radios -> 802.11b//n Look for failures in:

Load Profile (failed means more than 20 clients)

Noise Profile (failed means over -70 dBm)

Interference Profile (failed means more than 25%)

Coverage Profile (failed means a detected coverage hole)

A failure does not necessarily indicate a systemic problem, only an indicator a configured threshold has been crossed.

If you notice a lot of failures in the same area you may want to investigate.

WLANS Top Tab
Are there more than 5 active WLAN’s? The number of SSIDs should be kept to a minimum to avoid a negative performance impact because of excessive management traffic. Each SSID requires a separate beacon message that will be broadcast at the lowest mandatory data rate and can significantly impact the performance in a high-density design.

If you have 20 SSIDs and your 802.11b/g radios are left with the default settings, then the wireless cell is going to slow down to 1Mbps for a significant time window to send beacons and listen for responses.  This happens regardless of how many clients are communicating.  Issues will be very difficult to troubleshoot.

Within Each WLAN
General Tab
Is Broadcast SSID turned on? This is sometimes mistaken for a security feature.  It is recommended to leave Broadcast SSID as some client devices will not roam (or roam efficiently) with it turned off.
Security -> Layer 2 Tab
Is “Fast Transition” set to “Adaptive” (only on 8.3 or newer code) 802.11r Fast Transition is a feature introduced in 8.3 code.  At the time of this writing only Apple iOS10 devices support it.
Fast Transition can be Enabled, Disabled, or Adaptive.  If you want devices that support and do not support 802.11r then be sure to make Fast Transition “Adaptive”.
If WPA is enabled, is TKIP checked and AES unchecked? For those SSID’s that require data encryption and for those SSID’s that need to support legacy clients that do not support WPA2, only use WPA with TKIP and not with AES.
It is desirable to not have WPA enabled at all.
When WPA first came out the preferred encryption type was TKIP (104 bit key + 24 bit initialization vector = 128 bits total).  Later when WPA2 came along AES (256 bits) was added.  Most devices that NEED to use WPA will not be able to use AES.  If AES is enabled it could cause newer devices to use WPA with AES which will not allow 11n or faster data rates.

Read more at this Cisco Support Forums article.

If WPA2 is enabled (and it always should be except for guests or special cases), is AES enabled and TKIP disabled? For those SSID’s that require data encryption, make sure WPA2 with AES is selected and not TKIP.  AES (or no encryption at all) is required to get 11n or faster data rates.
There may be other options. Only select AES unless you are addressing a specific need and understand the implications.
If 802.1x is enabled, is CCKM enabled? Comment thanks to Javier Contreras Albesa: CCKM should not be recommended as a general feature to be turned on, unless you have client supporting it (792x phones, WGB, etc). 802.1x allows for a client authentication of several types (certificate, user ID and password, etc.).  Each time a client roams the authentication need to take place again.  CCKM is a mechanism Cisco has created to expedite that procedure, for devices that support it.

Read more about CCKM on the article 802.11 WLAN Roaming and Fast-Secure Roaming on CUWN

WIRELESS Top Tab
Any AP’s showing administratively down? Are there radios that are showing down?  Is there a known reason for them showing down? It is not uncommon to have some AP’s with radios that are administratively disabled.  It’s good to at least know why.
Are than any AP’s showing something other than PoE/Full Power or Power Injector / Normal Mode? Make sure there is a good reason if there are any AP’s showing something other than full or normal power mode. Most AP’s have a minimum power requirement of 802.1af (15.4W). Some AP’s, including 802.11n AP’s,  need higher power levels in order to enable the fastest data rates.  If a newer AP has reduced power it’s likely the fastest data rates will not be enabled.
What mode(s) is(are) the AP’s in? Make note and understand the implications of AP’s in Flexconnect or Connected (sometimes listed as Local) mode.  If there is a mix of Flexconnect and Connected/Local mode AP’s, make sure you understand why and the implications. AP’s in Connected/Local mode will tunnel all client data traffic to the controller and then be placed on the appropriate VLAN.  AP’s in Flexconnect mode will (typically) place client data traffic on an appropriate VLAN that is trunked to the AP.  Be sure to understand the implications of the desired design.
WIRELESS -> Access Points -> Radios -> 802.11a/n/ac
What channel sets are in use?

UNII-1: 36-48 (4 channels)

UNII-2: 52-65 (4 channels)

UNII-2b Extended: 100-144 (12 channels)

UNII-3: 149-161 (4 channels)

Generally (in the US) it is recommended to use UNII-1, UNII-2, and UNII-3.  Unless you are needing to support legacy devices (pre 802.11n), you should also enable UNII-2b Extended channels, allowing DFS to ensure they are allowed to be used.
How many channels do AP’s use (1 for 20 MHz, 2 for 40 MHz, 4 for 80 MHz) Do AP’s show multiple channels in the Channel column?  If yes, does the number of channels appear to be (at least generally) consistent?
If there are AP’s showing 4 channels in use (80 MHz wide) it will be important to understand why and the implications relating to channel availability.
Are any AP’s showing a channel number without an *asterisk? It is desired to have Radio Resource Management (RRM) manage channel assignments.  If your deployment has specific needs it is best to tune RRM so it makes the best decisions.  Note any channel that does not have an asterisk (*) following it and understand why this radio has a static (manual) setting.
Are any Power Levels showing a number without an *asterisk? It is desired to have Radio Resource Management (RRM) manage transmit power level assignments.  If your deployment has specific needs it is best to tune RRM so it makes the best decisions.  Note any Transmit Power that does not have an asterisk (*) following it and understand why this radio has a static (manual) setting.
Are than any power level 8’s? Power levels range between 1 (100%) and 8 (effectively off).  A power level of 7 is as low as it can go before it is turned off.
Do the power levels tend to be 3’s, 4’s, and 5’s? RRM should have the ability to increase or decrease transmit power levels to account for the always changing RF environment. If AP’s are mostly on power level 1 or 2, they may be placed too far apart from each other. If AP’s are mostly on 6, 7, or 8, AP’s may be too close to each other. In some cases you can account for AP’s being further apart or closer together by modifying the Power Threshold under WIRELESS -> Access Points -> 802.11a/n/ac -> RRM -> TPC.  Start with increments of 3.  Add 3 to get radios to generally be louder.  Subtract 3 to get radios to generally be quieter. The default is -70.
WIRELESS -> Access Points -> Radios -> 802.11b/g/n
Are there any channels in use besides 1, 6, and 11 and is there a reasonable mix of them? Make sure only channel 1, 6, and 11 is in use and there is a reasonable mix of them.  Never use other channels outside of the US.
Are any AP’s showing a channel number without an *asterisk? It is desired to have Radio Resource Management (RRM) manage channel assignments.  If your deployment has specific needs it is best to tune RRM so it makes the best decisions.  Note any channel that does not have an asterisk (*) following it and understand why this radio has a static (manual) setting.
Are any Power Levels showing a number without an *asterisk? Power levels range between 1 (100%) and 8 (effectively off).  A power level of 7 is as low as it can go before it is turned off.
Do the power levels tend to be 3’s, 4’s, and 5’s? RRM should have the ability to increase or decrease transmit power levels to account for the always changing RF environment.
If AP’s are mostly on power level 1 or 2, they may be placed too far apart from each other.
If AP’s are mostly on 6, 7, or 8, AP’s may be too close to each other.
In some cases you can account for AP’s being further apart or closer together by modifying the Power Threshold under WIRELESS -> Access Points -> 802.11a/n/ac -> RRM -> TPC.  Start with increments of 3.  Add 3 to get radios to generally be louder.  Subtract 3 to get radios to generally be quieter.
The default is -70.
WIRELESS -> 802.11a/n/ac -> Network
Are the supported, mandatory, and disabled data rates following best practices? Generally, if the lowest data rates are MANDATORY then clients will tend to experience roaming issues, stickiness, or unexplained dropped connections.

  1. Highly consider disabling all 802.11b data rates of 1, 2, 5.5, and 11.
  2. It is a best practice to AT LEAST make 12 Mbps Mandatory.
Comments thanks to Paul Chapman: Additionally, with 802.11b/g, by not having any mandatory rates above 11Mbps (default setting), you are allowing 802.11b clients on the cell. Unless you have to support them, b-clients are highly undesirable.

I would recommend setting the lowest mandatory rate to the speed you expect to support when clients start to roam, probably 24 Mbps. At a minimum set at least 1 mandatory rate above 11Mbps to prevent b-clients from coming onto the network.

Cisco White Paper: Cisco Wireless LAN Controller Configuration Best Practices

WIRELESS -> 802.11a/n/ac -> RRM -> TPC
Is Coverage Optimal Mode (TPCv1) selected? This is a default and is a best practice for most WiFi deployments.  Typically, TPCv2 is used in very specific circumstances.
Is Power Level Assignment Method set to Automatic? Since the RF environment is constantly changing, it is a best practice to use RRM. If the default settings of RRM are not appropriate for your environment, considering tuning it before changing the assignment method to fixed.
What is the Power Threshold set to? The default is typically -70 dBm.  If it is something other than that, it is important to know why.
WIRELESS -> 802.11a/n/ac -> RRM -> DCA
Is Channel Assignment Method set to Automatic? Since the RF environment is constantly changing, it is a best practice to use RRM. If the default settings of RRM are not appropriate for your environment, considering tuning it before changing the assignment method to fixed.
Is Channel Width following best practices? For high density client environments, it is a best practice to use 20 MHz.  It is typically not a best practice to use 80 MHz at all.  If the version of code you’re using has BEST as an option, this is typically recommended.
Are Extended UNII-2 Channels Enabled? Without UNII-2 Extended there are 12 channels available, or 6 with 40 MHz channels.  By using UNII-2 Extended, an additional 9 channels are available (or 12 channels if you have an AP that follows the new FCC rules (FCC Order 14-30)). Unless you are need to support older client devices that do not support UNII-2 Extended channels, be sure to use them.  It is rare devices do not support them.
Is ED-RRM Enabled? Event Driven RRM allows the RRM process to make immediate changes should a catastrophic interferer cause issue between RRM decision cycles.
WIRELESS -> 802.11b/g/n -> Network
Are the supported, mandatory, and disabled data rates following best practices? Generally, if the lowest data rates are MANDATORY then clients will tend to experience roaming issues, stickiness, or unexplained dropped connections.
WIRELESS -> 802.11b/g/n -> RRM -> TPC
Is Coverage Optimal Mode (TPCv1) selected? This is a default and is a best practice for most WiFi deployments.  Typically, TPCv2 is used in very specific circumstances.
Is Power Level Assignment Method set to Automatic? Since the RF environment is constantly changing, it is a best practice to use RRM. If the default settings of RRM are not appropriate for your environment, considering tuning it before changing the assignment method to fixed.
What is the Power Threshold set to? The default is typically -70 dBm.  If it is something other than that, it is important to know why.
WIRELESS -> 802.11b/g/n -> RRM -> DCA
Is Channel Assignment Method set to Automatic? Since the RF environment is constantly changing, it is a best practice to use RRM. If the default settings of RRM are not appropriate for your environment, considering tuning it before changing the assignment method to fixed.
Are channels other than 1, 6, and 11 in use? It’s important to use channels 1, 6, and 11 for RRM.  Any other channel set should be avoided.
Is ED-RRM Enabled? Event Driven RRM allows the RRM process to make immediate changes should a catastrophic interferer cause issue between RRM decision cycles.

Of course there may be other areas of your controller configuration that may provide health indicators and what works for you (and is healthy for you) may not be what is listed above.  This is simply a way to objectively gauge the health of your controller configuration.

For more insight in to how to tune your configuration, I recommend 3 Steps to Tuning a Cisco WLAN Controller From Default Settings.

Please let me know what you think in the comments section below.

I would like to acknowledge and thank contributors to this article:

3 Steps to Tuning a Cisco WLAN Controller From Default Settings

When I asked a few Cisco Wireless Consulting Systems Engineers if they’d ever trust a controller’s default config for any time of AP deployment beyond 1 or 2 AP’s the typical answer (when they stopped laughing) was <expletive> NO.

Of course I anticipated that answer and was prepared with a follow up: Okay what would you change? Now the answers to that were harder to get. Most said “well there’s too many variables,” or “every deployment is different.”

I was ready for that response, too. What’s the same with ALL deployments? Here’s a brief transcript:

Them: Is there VoIP clients?
Me: Let’s assume no, for now.

Them: What about 802.11b?
Me: No support.

Them: What about legacy devices?
Me: Nope. No legacy devices.

Them: What deployment style?
Me: Let’s use the 80/20 rule. 80% of deployments will be pervasive wireless network in common open environments where AP’s are deployed approximately 60ft-80ft or coverage areas of 3000-5000 sq/ft per AP. Let’s not focus on the interesting things that come with warehouses or outdoor environments.

Then I got answers. Here’s a consolidation of their suggestions. It’s 3 simple steps.

BEFORE YOU ATTEMPT THIS:

  • Your radios will be brought down during this procedure!
  • Know before you go:  If you aren’t sure what something will do, it may be better to not do it until you do!

NOTE: Most of these screenshots were taken from AireOS controller code 7.2 or 7.4. All of these suggestions are applicable for 7.5 and 7.6.

Step 1: Tune Each SSID

  • Click on the WLANs tab at the top of the page. This will show your SSID’s.
  • You select an SSID by clicking on the blue WLAN ID number to the left of the Profile Name.

  • Now click on Security.
  • Make sure that WPA2 with AES encryption is selected. (TKIP does not support 11n data rates. Only AES!)
  • If you must support WPA (like, something doesn’t work that needs to when it’s disabled) make sure you use WPA + TKIP and WPA2 + AES. Do NOT just select everything.
  • Now click on Advanced

  • Turn on BandSelect, it is off by default. Not necessary for WLANs with latency sensitive clients such as VOIP clients.
  • Some notes on this tab:
    • AAA Override will allow ISE (or another RADIUS server that supports it) to change VLAN or QoS queue based on authentication.
    • Client Exclusion is a nice security feature to protect against duplicate IP’s or brute force attacks. Sometimes you may need to turn this off for troubleshooting. 60 seconds is good Timeout Value to set.

Step 2: Tune the RF settings

  • First, in 2.4 GHz (802.11b/g/n)
  • Click the WIRELESS top tab
  • Click the BOLD 802.11b/g/n Network Left Hand Tab

  • Disable Network Status
  • Disable 1, 2, 5.5, 6, 9 and 11. This way no 11b data rates are supported.
  • Change 12 to mandatory.
  • Everything else change to supported.

A note about mandatory data rates: Lowest is where management frames are sent out. Highest one is where multicast/broadcast frames are sent out. A client must at least have the ability to do the mandatory data rates.

It is the client device responsibility to determine WHEN to roam and which AP to roam TO. A client will NEVER even try to roam until it reaches the LOWEST mandatory data rate!

  • Within 802.11b/g/n click onRRM > Dynamic Channel Assignment (DCA)

  • Check Avoid Persistent Non-WiFi Interference
  • Check EDRRM
  • Within 802.11b/g/n click on CleanAir

  • Enable CleanAir (this MAY already be checked)
  • Re-Enable the 802.11b/g/n radio under the 802.11b/g/n > Network left hand tab
  • Now for the RF settings in 5 GHz (802.11a/n/ac)

  • Up top click on Wireless, next on the left click on the Bold 802.11a/n/ac, then select Network.
    • Uncheck 802.11a Network Status to disable it as we will be making changes that required it to be turned off
    • Disable 6 Mbps
    • Disable 9 Mbps
    • Ensure 12 Mbps is Mandatory
    • Ensure 24 Mbps is Mandatory
    • Other data rates are Supported
  • Within 802.11a/n/ac click on RRM > Tx Power Control (TPC)
    • You have two options for RRM (Remote Radio Management).
    • o Interference Optimal Mode (TPCv2) will optimize the radio adjust power levels to detect and overcome external interference the AP discovers.
    • o Coverage Optimal Mode (TPCv1) will optimize the radio to adjust power transmit level based on neighboring AP’s it discovers.
    • o You can only have one Mode selected. TPCv1 is the recommended mode to select. TCPv2 is discouraged unless you have advance understanding of networking.
    • o If you are interesting in using TPCv2 here is a link on a helpful document and WLC Configuration Analyzer tool. https://supportforums.cisco.com/docs/DOC-1373
    • If the signal strength isn’t good enough across the entire network you can manually bump up the Power Threshold to -67 or more a little at a time, until RRM is properly tuned.
  • Within 802.11a/n/ac click on RRM > Dynamic Channel Assignment (DCA) and Event Driven RRM (EDRRM)

  • Check Avoid Persistence Non-WiFi Interference
  • Channel Width to 40 MHz
  • If you have the 802.11ac module you can select Channel Width to 80 Mhz. This will also auto tune the 802.11n radios to 40 Mhz.
  • Enable Event Driven RRM
  • Within 802.11a/n/ac click on CleanAir

  • Under the 802.11a/n/ac tab click on CleanAir
  • Top checkbox, Enable CleanAir
  • On Interferers to Detect add all
  • On Trap on these types under For Security Alarms add Jammer, WiFi Inverted, WiFi Invalid Channel
  • Re-Enable the 802.11a/n/ac radio under the 802.11a/n/ac > Network left hand tab

Step 3: Tune QoS

  • Click on the Wireless top tab, then QoS Left Hand Tab
  • For each QoS Profile, under Wired QoS Protocol Protocol Type select 802.1p. Tag number default is typically preferred.

And that’s it! Where this is not an exhaustive tuning guide, it serves as a starting point for just about any deployment style. For an exhaustive list, web on over to

Wireless LAN Controller (WLC) Configuration Best Practices.

Here’s a few other resources that may help.