Wireless Speed problem

[Sadettin Sahiner]

Hi everyone,

We have two different Cisco WLC 8540 located in different Cities ( City A and B ). Actually we have problem on APs which is registered on City B WLC. To make sure the problem is based on WLC, we connected two 2802i APs to same cisco 2960x switch. One of these AP registered to City A WLC, another AP registered to City B WLC and these APs mode were flexconnect. We also configured two ssid based on wlc, one of ssid locally switched another is centrally switched.The locally switched WLANs VLAN id was same on two of APs. Our topology as below.

If you connect to "Flex SSID City B" and perform speedtest to X server you are getting 60 Mbps/150Mbps ( down/upload ).

If you connect to "Flex SSID City A" and perform speedtest to X server you are getting 240 Mbps/250Mbps ( down/upload ). These are average results. The speedtest made with Huawei Mate 20 pro and software version is 10.0.0.188, and used  speedtest application. If you connect to Local SSIDs you also get similar results.

 We also performed jpref ( gui version of iperf ) test and we got similar results with speedtest. We sniffed wireless traffic during jperf test. As result  of this wifi sniff we saw that beacon time on City-B AP was randomly, but on City-A AP appromixly every 100 ms.  Our WLCs release was 8.5.131 . Actuallay we just opened case to TAC and they suggested upgrade from 8.5.131 to 8.5.161  after looked test results and configuration. We upgraded last night. We got similar results when did speedtest before and after upgrade.

Does anyone have recommendation ?

Thanks.

[Scott Fella]

Make sure that your connecting in the same channels and channel width on the 5GHz. 5ghz will provide higher overall throughput than 2.4ghz and the wider the channel, the more throughput you will see. Other than that, as long as you also test Iperf locally on each side to determine what is the max throughput you see, that is a good start. My suggestion is you have a dedicated ap that has a dedicated ssid and set that to 40mhz or 80mhz wide channel width and disable 2.4ghz and test.

[Sadettin Sahiner]

Hi Scott,

Thank you for your response.

In our test environment, channel width was fixed to 40 Mhz and channel was 60,64 for two of APs. And 2,4 Ghz interface state was Admin down. The 5 Ghz interface was open only in tested AP. 

[Scott Fella]

Well with your test AP’s in one location connected to different controllers and locally switched, you should see the same results since traffic doesn’t pass through the controller. The controller doesn’t even have to be reachable and the AP’s will still function. Maybe upgrade and see if that helps.

[patoberli]

Check if you have a different SSID configuration, for example QoS or mapped Policies.
Then there is AirTime Fairness (ATF), although I'm not sure if that is supported on Flex, but that could also cause lower throughput.

[Sadettin Sahiner]

If I move City-B AP to City-A WLC and back to City-B WLC it works properly. After this moving process if City-B WLC configure the City-B APs Rf environment ( DCA or Tx Power ) I am getting slow download results again. It is really weird problem. There is no qos configuration or etc on any devices and we don't need to.

[Scott Fella]

You try to factory reset the controller and build it from scratch. That is what I do when I observe odd behaviors. A backup and restore of the same config doesn’t work.

[Sadettin Sahiner · Accepted solution]

Hi everyone,

We solved the problem with A-MPDU configuration. Even though, our two WLCs have same config but, due to a bug which is effecting before 8.8 version configuration not applied to the City-B config. The A-MPDU config state was disable for all of packet ( priority from 0 to 7 ). After applying the configuration below, wifi throughput became to normal. To bu sure A-MPDU config, you have to check with "show 802.11a" command. 

config 802.11a disable network

config 802.11a 11nsupport a-mpdu tx priority 0 enable

config 802.11a 11nsupport a-mpdu tx priority 1 disable

config 802.11a 11nsupport a-mpdu tx priority 2 disable

config 802.11a 11nsupport a-mpdu tx priority 3 enable

config 802.11a 11nsupport a-mpdu tx priority 4 enable

config 802.11a 11nsupport a-mpdu tx priority 5 enable

config 802.11a 11nsupport a-mpdu tx priority 6 disable

config 802.11a 11nsupport a-mpdu tx priority 7 disable

config 802.11a enable network

Thanks for all your post.

[patoberli]

Oh wow, that means you probably had WLC configuration < 7.0 if I'm not mistaken, could that be?

[Sadettin Sahiner]

I did not understand what you mean with" WLC configuration < 7.0" but the WLC release is 8.5.161.

[patoberli]

In the very old releases, I believe before 7.0,those settings were different than what they are now. If you migrated your configuration or upgraded from those versions, the old settings remained.

[Sadettin Sahiner]

The WLCs are 8540. I don't how but we affected :)