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Beginner

Wireless LAN Very Slow

Company with ~500 employees. We have an AIR-CT2504-K9 wlc. We are experiencing very slow wireless connectivity.

 

Wired connections typically get 60mbps up and down. At the time of typing there are ~200 devices connected to our WLAN. We currently have 18 AP's deployed around the site. I am getting speeds of 3mbps down and 50mbps up while standing close to my AP's.

 

I have been informed that this slow connectivity is a new development.

 

Is this a case of managing expectations (number of clients vs. number of AP's), or are there settings I can play around with to boost the wireless bandwidth?

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13 REPLIES
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VIP Mentor

Re: Wireless LAN Very Slow

What AP models you got ? Also how your SSID configured WPA2-PSK ?

 

How many clients devices you see connect to one AP ? are they connect on 2.4GHz or 5GHz ?

 

Rasika

Beginner

Re: Wireless LAN Very Slow

A combination of AIR-LAP1142N-A-K9, AIR-CAP2702I-A-K9 and AIR-CAP3602E-A-K9 access points.

 

The AP I am currently on is an AIR-CAP3602I-A-K9 which has 15 clients connected to it.

 

8 of the clients are 802.11bn and 7 (including my cell phone) are 802.11an.

 

If I'm understanding my wireless protocols correctly - that means that 8 are 2.4GHz and 7 are 5GHz.

 

Our corporate and guest SSIDs use WPA+WPA2.

VIP Mentor

Re: Wireless LAN Very Slow

"Our corporate and guest SSIDs use WPA+WPA2"

Pls confirm under WPA+WPA2 parameters (WLNA -> Security tab) what encryption methods has been ticked.

 

Also check under Wireless -> 802.11a/n/ac -> DCA -> Channel width, what value has been checked (20/40/80/etc)

 

Typically if you want higher throughput, you have to focus on 5GHz.

 

For a given client, would you be able to  "show client detail <device_mac_addr>" output from your WLC to check what RSSI/SNR value clients got.

 

HTH

Rasika

*** Pls rate all useful responses ***

 

Beginner

Re: Wireless LAN Very Slow

Pls confirm under WPA+WPA2 parameters (WLNA -> Security tab) what encryption methods has been ticked.

AES and TKIP are ticked.

 

1.PNG

 

Channel width appears to be 20MHz - at least on the AP I'm connected to.

2.PNG

VIP Mentor

Re: Wireless LAN Very Slow

Untick that "TKIP" option & do a test & see.

 

HTH

Rasika

Beginner

Re: Wireless LAN Very Slow

Before change:

2.88 Mbps down | 55.4 Mbps up

 

After change:

4.25 Mbps down | 57.5 Mbps up

 

I've attached the output from the WLC for the device I am using.

VIP Mentor

Re: Wireless LAN Very Slow

That's a good. With TKIP, you cannot get any higher througputs (802.11n/ac speeds) even client is capable.

 

For 5GHz client you can improve throughput by channel bonding. Would you be able to share screenshot of Wireless -> 802.11a/n/ac -> RRM ->DCA  page.

 

HTH

Rasika

Beginner

Re: Wireless LAN Very Slow

Attached are the screenshots. Thank you very much for your assistance.

 

 

DCA1.PNGDCA2.PNG

 

DCA3.PNG

 

DCA4.PNG

VIP Mentor

Re: Wireless LAN Very Slow

I would suggest to change it to 40MHz.

 

This will be a disruptive change, momentarily (so do it during agreed maintenance window). You have to  to disable 802.11a network first (Wireless -> 802.11a/n/ac -> network -> 802.11a network status-> untick first).

 

Then change DCA value to 40MHz

 

Re-enable 802.11a network status.

 

After that test with same client & see

 

HTH

Rasika

Beginner

Re: Wireless LAN Very Slow

It says I have to disable the network in order to change the channel width. When I try to do so, I get this message. Can I disregard it?

 

Capture.PNGCapture2.PNG

VIP Mentor

Re: Wireless LAN Very Slow

Yes, you can disregard & continue (as I said earlier, this will disable 5GHz band until you enable it again, so any client connect on 5GHz will be disturbed during this time)

 

HTH

Rasika

Beginner

Re: Wireless LAN Very Slow

After change:

 

4.89 Mbps down | 56.3 Mbps up

VIP Mentor

Re: Wireless LAN Very Slow

I would encourage you to test with multiple devices. Each client device got different capability (pls check below site for each clients capability)

https://clients.mikealbano.com/

 

Theoretical data rates values (depend on modulation, number of spatial stream, channel width) can be found in below table

http://mcsindex.com/

 

When you have different type of clients on same cell, then overall throughput for each clients get reduced. Therefore you will see much lesser values compare to those MCS table values. That is normal.

 

Also see if you can use iperf to measure network speed, below post may help you on that

https://mrncciew.com/2014/08/08/how-fast-is-your-network-iperf/

 

HTH

Rasika

 

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