SA520W - WLAN ping response from 1ms to 3.000ms and more?!

Unanswered Question
May 19th, 2010
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Hi everyone,

I am experiencing problems with my SA520W.

The SA is connected to a motorola broadband cable-modem. WAN connection is fine with good response times.

If clients are connected via cable to the SA, the overall performance is very good.

If clients (3 Windows 7 PCs with N-standard) are connected to the SA via WLAN, I am expeiencing an unpredictable behaviour in connectivity and ping response times from the SA.

WLAN connectivity itself is good (approx 15 meters from the SA).

Sometimes clients can connect without problems, sometimes not.... (need 2 or 3 manual reconnects).

If a ping -t  is initiated from the client to the SA, it is normally below 2ms.

If a browser is started (eg. Explorer8 or Mozilla) connectivity is good for a short time. After a while, ping degrades to eg. 400ms and gets worse after a minute to over 3000ms.

I have no idea, what could cause this behaviour, since a wireless connection doesnt show this effect.

Same effect with mixed radios/standards (N/G)....

Firmware is the newest.

If someone has a good idea, please give me a hint.

If more informations are required, tell me what you need.

Thanks for any help!


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biraja Wed, 05/19/2010 - 12:37
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Hello Markus,

Could you post the firmware version info and the config?



allestester Thu, 05/20/2010 - 11:24
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actual version is 1.1.42.

which part of the config are you interested in?


charlesw Mon, 05/24/2010 - 16:26
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  • Cisco Employee,


We are currently investigating this issue.

May we acquire your wirless profiles?  Basicly what type of security profile are you using, and/or if you used the WPS to configure your clients?

Also, which address are you pinging?   The gateway address of SA or the WAN address?  Your information is appreciated.



allestester Wed, 05/26/2010 - 12:14
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I was pinging the SA520w, not the WAN.

As I mentioned earlier, if a client PC is connected with cable, these high response times don't occur (neither with pinging the SA nor pinging a public IP).

These high response times just show up with the wireless connection (pinging the SA an the WWW)....

Until now, I didn't change the config of the SA, but I implemented a WLAN repeater (manufacturer AVM for b/g/n standard) just using the "n" standard.

The distance between the SA an the repeater is about 5 meters, from the repeater to the clients additional 5 meters.

Right now, the connection is pretty stable and responsive (around 10 ms) to the SA via the repeater.

I didn't use WPS to configure the clients (all done by hands). WPS is disabled on the SA.

Changing QOS didn't help either. Didn' change anything in advanced radio settings.

I am posting a screenshot (or more), showing the WLAN profiles.

If you need something else, please contact me.

Thanks very much in advance,


charlesw Thu, 05/27/2010 - 18:35
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  • Cisco Employee,

Hi Markus:

Thanks for your reply, I am glad to see you have found a tempory solution for the issue.

Based on your respond, I am suspecting there might be some sort of interference on the signal.  Is there a microwave oven, or steel file cabinet between your client PC and the SA?  Or perhaps another device operating at the same channels? If you move your client PC (hopefully is a laptop) closer to SA, do you still experiencing the issue?

We will keep an eye on this issue. We will also do some test to see if we can reproduce your issue.  We will keep you updated.

Thank you for being patient with us, we really appreciate your business.

Best Regards,


allestester Fri, 05/28/2010 - 11:44
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Hello Charles,

thanks for helping so far...

From my point of view, there are no interferences.

There are serveral WLANS around, but changing the channels didn't help. Also auto-channel-selection doesn't help.

I posted two new screenshots for my problem.

The installed repeater might help a bit, but the basic problem remains.

In screenshot 5 you can see the typical response times to a ping (pinging in parallel OVER WLAN).

On the left side, you see the response from the SA.

On the right side, you see the response from the WAN.

=> real bad on the WAN side!

In screenshot 6 you can see the typical response times to a ping  (pinging in parallel OVER LAN).

On the left side, you see the response from  the SA.

On the right side, you see the response from the WAN.

=>  good on both sides!

The time between both screenshots is 2 minutes (moving the laptop an cabling it via RJ45).

So any kind of interference shouldn't be the problem...

I expected it to be a kind of DNS problem, but where should be the difference in a LAN or WLAN connection?

To complete my confusion...

Please see sreenshot 7.

This is the ping response over WLAN, when I am 1 Meter beside the SA!!!!

Thanks for your further help!



charlesw Fri, 05/28/2010 - 16:23
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Hi Markus:

Thank you for your repsonds.  To further help you, we will need your configruation file.  Can you PM me your configuration file?

I did some test to emulate your setup, I did not experience the same issue.  I have attached my test results in "ping.jpg".  My client is siting about 15 meters away with walls between my client and SA.

May I ask if I can get a screen shot of your SNR ratio?  Such as shown in the "SNR.jpg?

You mention you think it's a DNS issue, if you ping the address directly, would you still get this long latency?

Your screen shot 6 and 7 looks similar, so, it seems to indicate when your client are closer to  the SA, it doesn't have the issue. (Your 7.jpg pinging the have avg latency of 13ms)

I am still suspect that there might be some noise issue that's interfering your wireless signal.  



allestester Sat, 05/29/2010 - 04:54
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Hello Charles,

thanks so far.

You mentioned:

Your screen shot 6 and 7 looks similar, so, it seems to indicate when  your client are closer to  the SA, it doesn't have the issue. (Your  7.jpg pinging the have avg latency of 13ms)

Yes, thats correct.

The closer the client is to the SA, the better the WLAN connection gets,   BUT!!!!

1.) Pinging the SA over WLAN is (not always) good in response times (close to SA or far away)

2.) Pinging a WAN address delivers good response times over WLAN, when you are close to the SA

3.) Pinging a WAN address delivers bad response times over WLAN, when you  are far away to the SA

So, how can there be a difference in response times for WAN addresses depending on the clients distance to the SA WHEN YOU ARE RECEIVING GOOD RESPONSE TIMES FROM THE SA   AT THE SAME TIME !!!!!

How can Ping times to the WAN degrade, when moving away from the SA  when the ping to the SA remains good AT THE SAME TIME ????

Didn't find a tool for SNR that works with Atheros....

Thanks Markus

charlesw Thu, 06/03/2010 - 14:54
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Hi Markus:

Thanks for working with us on debugging this issue.  I have tried several possible scenarios, but unable to reproduce your issue onsite.

I suggest that we open a TAC case to track your issue.  Please feel free to call 1-866-606-1866 to open a case, please refer to this community thread so they won't ask too much repeated questions.

Before you open the case, can you try the following?

1.  Make sure the antennas on the back of SA are securely tighten.  Loose antenna sometime gives weak/unreliable signals.

2.  Back up the configuration and power cycle the box.  This is an attempt for a work around, I suspect if there is a memory leak somewhere, it might also interfere with the process.

Can you also provide me a trace route to your WAN connection when the issues happens?  I would like to see at which link is the delay occurs.

In my setup, if my signal gets too weak, I get a "Request timed out" instead of a long latency.

Also, if you could PM me your configuration, I would like to see if I can reproduce your issue with your configuration.  Mainly, want to see if there are other configuration such as IP alias, load balancing, or firewall that might interfer with the process.

Thank you again for your help.  I apology for any inconvenience.



allestester Mon, 06/14/2010 - 12:22
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hello charles,

antennas are tightened and a powercycle didn't help.

I did some more screenshots.

The three permanent pings show the responsetimes OVER WLAN (from left to right)

=> 1. my SA520  2. the WAN IP address of  3. ping to

Also, I made the requested traceroute.

The upper tracert to was done over the WLAN connection

The lower tracert to was done, when connected over LAN to the SA520.....

The time-difference between both tracert was 20 sec.

Any ideas left?

Thanks for helping.

Please send me your mailaddress, so I can send you the config of the SA.

With kind regards


sigolaper Wed, 11/10/2010 - 12:21
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I would like to report that I'm having the same issue with my SA520W.

I started a thread some days ago here:

Have you found any solution to this?

The only way I can get this to work satisfactory, is to not use the wireless features of the 520W, and use a completely different AP connected to the network.


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