Sudden drop in speed and response time across all SSID and radios!

[Steve_Ballantyn]

Yesterday I had a complaint that a few clients at a remote office were having poor response times. Their ping response time was around 100-400ms, whereas it's usually it's less than 6ms. I could not see any indication that the bandwidth between their facility and ours was stressed. Not really knowing what to try, I rebooted all of their AP's one at a time. The problem seemed to go away, but I am not sure that rebooting things actually solved it.

This morning, I noticed I was having lag myself. I am the main facility where all of the traffic comes back to the controller. I am in a room with an Extreme switch and a 3825i AP. When I plug into the switch, I am getting 1ms response time. Using wireless I am getting anywhere from 30ms to 100ms. It sometimes jumps to 400ms or so (yuck).

I have tried the following to no avail:
Switching SSID's (my guest network and some other segregated ones)
Changing between 802.11n, 802.11bg, and 802.11ac
Switching radio channels (forced from channel 6 to several others)
Rebooting the AP
Looking through EMS Application Flows looking for abuse
Looking through my Wireless admin console for clues (using Reports)
I don't see anything wrong with the general bandwidth at any point in the connection process. It really seems like the controller is doing something fruity out of the blue. I would love to reboot it. But I waited too long into the morning and I would cause pain to a lot of users if I flipped the switch right now.

Can anything think of something that I can check or quickly reset?

I am using 3825i's (80 of them across my facility) and they are Bridged@Controller for the most part. I am running Software version 10.11.02.0032 on a 5210 controller.

Thanks for any clues or advice!!

[Steve_Ballantyn]

I updated to the latest code last night, and this morning all seems well again on my network. Response times are normal. Also the controller admin pages are quite snappy, and I remember them lagging a bit as I went through the various menus yesterday. I think there was probably just something funny going on with the controller. Maybe a runaway process or a memory hog of some sort.

Thanks everyone for all the advice and explanations!

[Nathiya_Munuswa]

The DTIM is how the AP (wireless router) warns its clients that it is about to transmit the multicast (and broadcast*) frames it queued up since the previous DTIM.

This queueing and scheduled delivery is done to allow power-conscious devices to save power by turning off their receivers for brief stretches of time, only waking up their receivers when the AP indicates is has traffic for them. This procedure is only performed if one or more of the currently-associated clients on the AP is in power-save mode. If no clients are in power save mode, the AP will transmit "multicasts or broadcasts" as soon as they come in.

A shorter DTIM interval could theoretically make your wireless devices use up their batteries faster, because they'd have to wake up more often for multicasts. A longer DTIM interval could theoretically hinder multicast (and broadcast*) performance on your network.

[Steve_Ballantyn]

Hello Nathiya - thank you for that explanation!

[Umut_Aydin]

Hi Steve,

you can try this before ´making a FW upgrade.

Change the DTIM setting from 5 to 2 in the WLAN Services under advance button.

If it doesn't make it ..then use this article.

https://gtacknowledge.extremenetworks.com/articles/Solution/Wireless-Clients-has-performance-and-con...

Did you made a upgrade shortly ?

There is lot of fixes in the newest code which could also solve the issue.

Regards
Umut Aydin