Improving Wireless Performance

[Stephen Carville]

I have been getting lot of complaints from the C-level about the speed of the wireless network.  Tests on the wired network yield 700+ Mbps but the wireless strains to reach 24 Mbps.

I do not expect the wireless network to match the wired network in speed or reliability but the above does seem a bit of an excessive difference.  Is there any good documentation on improving wireless performance?

Controller: 5508 (two configured as active-passive)
Access Points: AIR-CAP3702E (17 local; 29 total)
All APs are in Flex-Connect mode.

[Martin Carr]

You really need to provide more information, for example what band are the clients connecting? What channel? To what standard? Are the effected clients all connected to one AP?

It's never a bad idea to perform a spectrum analysis, as it gives an insight to the environment, it may be there is a lot of co channel interference or congestion, or some external interference.

Martin

[Leo Laohoo]

1. What firmware is the controller running on?
2. How are you testing this? Did you go to www.fast.com (recommended) or www.speedtest.net (thumbs down)?
3. What kind of wireless NIC? Make and model
4. What is the driver version of the wireless NIC?
5. What radio was this "test" conducted on? 2.4 Ghz (thumbs down) or 5.0 Ghz?

Hold on, 3702E? ALL OF THEM????
I hate to ask, but what kind of deployment is this? Warehouse?

[Stephen Carville]

I am not sure if this is what you are asking for but show sysinfo lists

Product Version.................................. 8.0.120.0
Bootloader Version............................... 1.0.20
Field Recovery Image Version..................... 7.6.95.16
Firmware Version................................. FPGA 1.7, Env 1.8, USB console 2.2

I tested doing a file transfers with ftp and sftp. That is what the bigshots are complaining about. I also use the speed test at http://www.dslreports.com/speedtest to test connections to the outside world.

I do not know what Wireless NIC the wheels are using. All I really know is they are using MACs. I tested using a Dell Latitude E6540 which probably uses the built in wireless. The latop is running CentOS 6.10. The kernel version is 2.6.32. The driver module is iwlwifi which covers quite a few Intel chipsets.

I tested both 2.4 and 5 Ghz. Both seemed to transfer files at about the same speed.

[Scott Fella]

I think you need to investigate a few things. Like the other poster has mentioned, have you looked at the spectrum? Do you have enough coverage where they sit and with the doors closed in their office? What signal do you see their devices on when looking at the controller? How many devices are connected to the AP’s, average and max per day? How many devices are connected to 2.4GHz vs 5GHz, you really want to be on 5GHz, but that goes back to my first two questions, having good signal and SNR inside their offices and meeting rooms.

You should post your configuration and scrub out info to hide so that we can see how your bands are defined and your SSID’s.

[Stephen Carville]

I used a Fluke One Touch AT to check the signal strength in the offices and conference rooms. The SSID they connect to varies from -46 dBm to -52 dBm.  The access point I am using to test registers about -45 dBm

The Air Quality Reports averages 99% to 100% for 802.11a/n/ac and 95% to 99% for 802.11b/g/n.

According to the 5508, the laptop I am using for testing is connected via 802.11an which, if I understand the nomenclature correctly, is 5 GHz.

Everything looks pretty good to me.

Using sftp, I just transferred a 1.07 G file in 3m 27s which translates to 5.2 MB/s or about 41 Mb/s.

My configuration is attached.

[jmanzanera]

Hello,

I think you are only checking the signal strength on the mentioned rooms and the signal strenght could be one factor to slow teh wifi, however it seems is not your issue.

Can you provide more information about your Wi-Fi configuration as :

 - Are you using Band Steering on your SSID?

 - Are you using separate SSID for 2.4 Ghz and 5 Ghz? If not, I highly recommend to do it due one 2.4 Device could slow your Wi-Fi significally.

 - Are you using RF profiles? Maybe are you using teh defailt one? If yes which is the beacon that you are using?

I think (wihtout the information requested) your porblem could be located on the beacons that you are using. This could cause that one client will be connected to one AP that is not the better one on that location (maybe the roaming didn't complete correclty).

[Stephen Carville]

---

@jmanzanera wrote:

 - Are you using Band Steering on your SSID?

I had to look up Band Steering/Select and I am not using it. I turned it up on the test SSID I am using and it connects at 5.745 GHz but only transfers at about 35 to 40 Mb/s over sftp. I know sftp is slower than ftp or nfs but sftp is what the big shots want to use. I can get sustained speeds of 700 to 800 Mb/s from sftp over a wired conenction.

 - Are you using separate SSID for 2.4 Ghz and 5 Ghz? If not, I highly recommend to do it due one 2.4 Device could slow your Wi-Fi significally.

I didn't know that I could even force a SSID on the 5508 to use 2.5 versus 5 GHz. I can certainly setup separate SSIDs for most of the users. At least one SSID will have to support 2.5 because some devices on the network just do not support 5 GHz.

 - Are you using RF profiles? Maybe are you using teh defailt one? If yes which is the beacon that you are using?

As near as I can tell, I have no RF profiles defined.

I think (wihtout the information requested) your porblem could be located on the beacons that you are using. This could cause that one client will be connected to one AP that is not the better one on that location (maybe the roaming didn't complete correclty).

---

That could be. Could FlexConnect have anything to do with it? I use it because there are APs at remote offices that are managed by the 5508.

[patoberli]

What encryption are you using on the SSID?
> 802.11n and AC speeds are only possible if WMM is enabled (not disabled) and you use WPA2 with AES (or no encryption at all). WPA, WEP and/or TKIP all don't support high speeds.
Can you check the MAC address of a client and then issue the following command on the wlc:
show client detail herethemacaddress

Please post the full output of that command (you can remove the username, IP addresses and ssid name if you like).

[Stephen Carville]

Here is the output. Seems a little odd it doesn't support rates over 54 Mb/s. I checked some other machines -- Windows and Macs -- and they all seem to have the same limit. Guess I need to do some more studying.

Client MAC Address............................... 80:00:0b:8a:d2:c5
Client Username ................................. N/A
AP MAC Address................................... 58:97:bd:3e:2d:b0
AP Name.......................................... Co5897bd26e720.lereta.net 
AP radio slot Id................................. 1  
Client State..................................... Associated     
Client User Group................................ 
Client NAC OOB State............................. Access
Wireless LAN Id.................................. 3  
Wireless LAN Network Name (SSID)................. LeretaNW
Wireless LAN Profile Name........................ LeretaNetWork
Hotspot (802.11u)................................ Not Supported
BSSID............................................ 58:97:bd:3e:2d:be  
Connected For ................................... 209 secs
Channel.......................................... 60 
IP Address....................................... 10.212.56.12
Gateway Address.................................. 10.212.56.1
Netmask.......................................... 255.255.255.0
Association Id................................... 1  
Authentication Algorithm......................... Open System
Reason Code...................................... 1  
Status Code...................................... 0  
Session Timeout.................................. 0  
Client CCX version............................... No CCX support
QoS Level........................................ Silver
Avg data Rate.................................... 0
Burst data Rate.................................. 0
Avg Real time data Rate.......................... 0
Burst Real Time data Rate........................ 0
802.1P Priority Tag.............................. disabled
CTS Security Group Tag........................... Not Applicable
KTS CAC Capability............................... No
WMM Support...................................... Enabled
  APSD ACs.......................................  BK  BE  VI  VO 
Power Save....................................... OFF
Current Rate..................................... m10
Supported Rates.................................. 6.0,9.0,12.0,18.0,24.0,36.0,
    ............................................. 48.0,54.0
Mobility State................................... Local
Mobility Move Count.............................. 0
Security Policy Completed........................ Yes
Policy Manager State............................. RUN
Policy Manager Rule Created...................... Yes
Audit Session ID................................. 0ad4035b000252f05bbf939a
AAA Role Type.................................... none
Local Policy Applied............................. none
IPv4 ACL Name.................................... none
FlexConnect ACL Applied Status................... Unavailable
IPv4 ACL Applied Status.......................... Unavailable
IPv6 ACL Name.................................... none
IPv6 ACL Applied Status.......................... Unavailable
Layer2 ACL Name.................................. none
Layer2 ACL Applied Status........................ Unavailable
Client Type...................................... SimpleIP
mDNS Status...................................... Disabled
mDNS Profile Name................................ none
No. of mDNS Services Advertised.................. 0
Policy Type...................................... WPA2
Authentication Key Management.................... PSK
Encryption Cipher................................ CCMP (AES)
Protected Management Frame ...................... No
Management Frame Protection...................... No
EAP Type......................................... Unknown
FlexConnect Data Switching....................... Local
FlexConnect Dhcp Status.......................... Local
FlexConnect Vlan Based Central Switching......... No
FlexConnect Authentication....................... Central
FlexConnect Central Association.................. No
Quarantine VLAN.................................. 0
Access VLAN...................................... 56
Local Bridging VLAN.............................. 56
Client Capabilities:
      CF Pollable................................ Not implemented
      CF Poll Request............................ Not implemented
      Short Preamble............................. Not implemented
      PBCC....................................... Not implemented
      Channel Agility............................ Not implemented
      Listen Interval............................ 10
      Fast BSS Transition........................ Not implemented
Client Wifi Direct Capabilities:
      WFD capable................................ No
      Manged WFD capable......................... No
      Cross Connection Capable................... No
      Support Concurrent Operation............... No
Fast BSS Transition Details:
Client Statistics:
      Number of Bytes Received................... 13937
      Number of Bytes Sent....................... 35216
      Total Number of Bytes Sent................. 35216
      Total Number of Bytes Recv................. 13937
      Number of Bytes Sent (last 90s)............ 1660
      Number of Bytes Recv (last 90s)............ 1466
      Number of Packets Received................. 135
      Number of Packets Sent..................... 340
      Number of Interim-Update Sent.............. 0
      Number of EAP Id Request Msg Timeouts...... 0
      Number of EAP Id Request Msg Failures...... 0
      Number of EAP Request Msg Timeouts......... 0
      Number of EAP Request Msg Failures......... 0
      Number of EAP Key Msg Timeouts............. 0
      Number of EAP Key Msg Failures............. 0
      Number of Data Retries..................... 215
      Number of RTS Retries...................... 0
      Number of Duplicate Received Packets....... 2
      Number of Decrypt Failed Packets........... 0
      Number of Mic Failured Packets............. 0
      Number of Mic Missing Packets.............. 0
      Number of RA Packets Dropped............... 0
      Number of Policy Errors.................... 0
      Radio Signal Strength Indicator............ -78 dBm
      Signal to Noise Ratio...................... 19 dB
Client Rate Limiting Statistics:
      Number of Data Packets Received............ 0
      Number of Data Rx Packets Dropped.......... 0
      Number of Data Bytes Received.............. 0
      Number of Data Rx Bytes Dropped............ 0
      Number of Realtime Packets Received........ 0
      Number of Realtime Rx Packets Dropped...... 0
      Number of Realtime Bytes Received.......... 0
      Number of Realtime Rx Bytes Dropped........ 0
      Number of Data Packets Sent................ 0
      Number of Data Tx Packets Dropped.......... 0
      Number of Data Bytes Sent.................. 0
      Number of Data Tx Bytes Dropped............ 0
      Number of Realtime Packets Sent............ 0
      Number of Realtime Tx Packets Dropped...... 0
      Number of Realtime Bytes Sent.............. 0
      Number of Realtime Tx Bytes Dropped........ 0
Nearby AP Statistics:
      Co188b9dc09778.le(slot 0)
        antenna0: 73 secs ago.................... -76 dBm
        antenna1: 73 secs ago.................... -77 dBm
      Co188b9dc09778.le(slot 1)
        antenna0: 72 secs ago.................... -82 dBm
        antenna1: 72 secs ago.................... -80 dBm
      Co188b9dc09b54.le(slot 0)
        antenna0: 132 secs ago................... -90 dBm
      Co5897bd26e720.le(slot 0)
        antenna0: 72 secs ago.................... -75 dBm
        antenna1: 72 secs ago.................... -76 dBm
      Co5897bd26e720.le(slot 1)
        antenna0: 70 secs ago.................... -86 dBm
        antenna1: 70 secs ago.................... -83 dBm
DNS Server details:
      DNS server IP ............................. 10.212.3.26
      DNS server IP ............................. 10.212.3.27
Assisted Roaming Prediction List details:


 Client Dhcp Required:     False
Allowed (URL)IP Addresses
-------------------------

AVC Profile Name: ............................... none

[patoberli]

Based on this output you seem to have ok speed:
Current Rate..................................... m10
But the signal is quite weak:
Radio Signal Strength Indicator............ -78 dBm

Encryption looks fine, so does WMM.
Just to be sure, can you check on the WLC under Wireless -> 802.11a/n/ac -> High Throughput if everything is enabled there?

[Stephen Carville]

---

@patoberli wrote:
Based on this output you seem to have ok speed:
Current Rate..................................... m10
But the signal is quite weak:
Radio Signal Strength Indicator............ -78 dBm

I noticed the weak signal so I restricted the test SSID I set up to only the AP closest to me. It looks a little better now though the fact it was necessary indicates an issue with clients not always connecting to the AP with the best signal.

Current Rate..................................... m14
Supported Rates.................................. 6.0,9.0,12.0,18.0,24.0,36.0,
    ............................................. 48.0,54.0

Radio Signal Strength Indicator............ -51 dBm
Signal to Noise Ratio...................... 45 dB

Encryption looks fine, so does WMM.
Just to be sure, can you check on the WLC under Wireless -> 802.11a/n/ac -> High Throughput if everything is enabled there?

---

I checked and both 11n and 11ac modes are enabled.

BTW, what does a current rate like m10 or m14 mean?

[patoberli]

Have a look here for an explanation of the rates:

https://community.cisco.com/t5/wireless-mobility-documents/how-to-interpret-802-11ac-datarates/ta-p/3151995

It's a tad weird, that it doesn't show the amount of streams on your output, but might be a software version thing.

In any case, you seem to be connected at a fairly good speed, how do you measure the performance?

I suggest to use a wired client running iperf in server mode and a wireless client running it in client mode.

[Stephen Carville]

Thank you for the reference. It is very helpful

I was using SFTP to transfer files because that and FTP is what the developers are using. The transfer rates I get from iperf are consistent with the sftp speeds. EG:

------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
[  4] local 198.204.114.92 port 5001 connected with 10.212.56.131 port 45106
[ ID] Interval       Transfer     Bandwidth
[  4]  0.0-10.2 sec  35.4 MBytes  29.1 Mbits/sec
------------------------------------------------------------
Client connecting to 10.212.56.131, TCP port 5001
TCP window size: 81.2 KByte (default)
------------------------------------------------------------
[  4] local 198.204.114.92 port 59024 connected with 10.212.56.131 port 5001
[  4]  0.0-10.1 sec  51.6 MBytes  43.1 Mbits/sec

I have to come in tomorrow evening to run some patches and I will bring in my personal laptop which has better diagnostic tools.

[patoberli]

Ok great. What is the channel width you have configured on the 5 GHz interface of your test AP?
Please note 30 and 43 Mbit/s are fairly close to the possible maximum you get with an 802.11n 1SS client on 2.4 or 5 GHz with a 20 MHz channel. That is in a somewhat busy environment. In a basement you can reach up to around 70 Mbit/s with the same test client.

The world looks way different if you go for 80 MHz channels and a 3SS client which runs 802.11ac, that can reach up to 500 Mbit/s realistically.

What connection speed is shown on the test client?
See here on how to show this data: https://www.tenforums.com/tutorials/75371-see-network-adapter-speed-windows-10-a.html

You shouldn't use encrypted protocols (like SFTP) to test bandwidth, because the encryption can be very heavy on the client CPU and produce wrong data.