Wireless clients face latency issues

[ravisambaji]

Hi Friends,

I have Cisco 1140 access points and 5508 controller in my network. I have configured 2 SSIDs. One SSID is working fine, we have issue with second SSID. Clients getting connected to second SSID are facing the latency issue, latency is around 1000 ms where as with first SSID the latency is around 100 ms.

The layer-3 gateway for the user VLANs is in switch. The link between controller and L3 switch is trunk port and we have allowed only required vlans on the trunk. We even configured seperate test ssid and mapping to different vlan id.. still we face the same issue.

What could be the issue, help is appreciated.

Regards

Ravi

[Scott Fella]

That is a high latency. Did you try to isolate where the latency starts? If you did a trace route is it somewhere in the wan? I'm guessing it's over the wan with those times.

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[ravisambaji]

Hi Scott,

When user pings his gateway ip address, we see the latency. i don't see the latency in the wan. where is latency for users connecting to other SSID is less than 100 ms.

Regards

Ravi

[Scott Fella]

Okay... So now is it one user or all users on that SSID. Have you looked at the logs on the wlc and even in the switch to see if you have errors. If you connect a wired pc to that subnet, do you still have high ping times?

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[ravisambaji]

when i connect the wired users on the same subnet, i don't have the latency issues.

[Scott Fella]

What are the ping time from the wlc to the gateway. Is it one user or everyone?

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[ravisambaji]

the ping latency from WLC to gateway is less than 10 ms.

[Scott Fella]

Then I would check the client device then. Maybe a driver issue or configuration issues. Seems to be pointing to that if your ping times frim the wlc to that gatway is low. You can run a debug on the client also if you want.

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[ravisambaji]

we have tried with multiple laptops, same laptop works fine with other SSID.

[George Stefanick]

Have you tired taking the WLC and wireless out of the mix and stretch the vlan to the wired side and see what happens?

[Scott Fella]

Try no authentication and see if the problem goes away. You need to try to eliminate all factors. Is both SSIDs setup using the same authentication method? If you swap the interface around does this issue still exist with the SSID or the subnet? If you are using PSK, try to use either wpa/tkip or wpa2/aes, not both at the same time.

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[ravisambaji]

ur trying to suggest there is problem in the wired network but not the wireless part. Iam a data guy have ensured there is no problem in this portion. need to look at if some of the features in the wlc related to ssid or vlan etc can be enabled/disabled to get it back to working.

[ravisambaji]

tried with no authentcation as well.. no luck..

[George Stefanick]

I would try swapping the interfaces as scott suggested or build a different WLAN for testing. Strip it down to nothing ... Also both your SSIDs, do they allow ALL radios ? I mean is your SSID1 conecting to 2.4 ghz and your SSID 2 is connecting to 5 GHz?

[Scott Fella]

Here is a good guide and it's something we all try to follow one way or another.

http://www.cisco.com/en/US/products/ps6366/products_tech_note09186a00809d45a2.shtml

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