2504 running on 8.5.151.0 - bandwidth issues

[danailpetrov]

Hi guys,

I am having some weird problems with my 2504 controller running on 8.5.151.0 

I noticed today that I am unable to achieve more than 30-32Mbps on an individual device. It's like there is a hard-cap that doesn't let the device getting more bandwidth. 

I have played alot, trying to tweak different QoS settings, but apparently 2500 is very limited in configuration of the bandwidth rates, burts and traffic profiles. I was unable to find a way to completely disable the qos for an SSID and just let it be on "best effort". 

My questions are: 

* are there any built-in, default policers for different classes and if so - what are the values? 

* Is there anyway possible I can completely switch off that behaviour (preferably on a per SSID basis?)

* Is that an 8.5.151.x problem because I don't recall having this problem on older versions

[Scott Fella]

You didn't enable "fastlane" did you? That is part of the best practice and might be the issue. Like I mentioned before, if you test with a new open ssid that has the basic config and no crazy features enabled, I bet your experience will be better. Then slowly add features and see when it breaks. Then you have the data to understand what you need to do on your other ssid.

[danailpetrov]

Thanks for your response, Scott. 

Fast lane has been always on. I have another SSID for IOT, where everything is basic and it's pretty much the same experience. 

The approach you're suggesting is absolutely fine, if we consider this is a green-field implementation so starting fresh/from scratch makes perfect sense. The problem here is that this setup has been running for 2+ years now and I only recently started experiencing this problem - no changes have been done whatsoever (other than changing the OS and trying to turn some knobs off/on as part of the troubleshooting). 

[patoberli]

I don't assume the LAN port has switched for whatever reason to 100 Mbps between WLC and Switch? Or maybe a lot of interface errors on it?

[danailpetrov]

it is most certainly not the case. No errors reported on the switch (other than a very few output discards (which are quite typical for the 2960s)) but there is 4x1G LACP port-channel between the WLC and the switch .. :| 

[patoberli]

Just for testing, can you unplug three of the four LAN cables building the LACP? A broken LAG / LACP could cause this, although rare.

[danailpetrov]

hi,

to be honest I have never experienced any similar problem with LAG/LACP and I don't see how any of that could have caused buffering/increased latency, but I still tried to do pull 3 members of the Po and leaving on single iface only and it didn't make any difference.. 

Does anyone know if I can somehow drop into the bash or at least get some output results from the WLC's kernel for the queueing? I found a way to check routing entries, iptables, etc, but what I'm really curious of is checking the 'tc' (traffic control) settings. 

[Scott Fella]

If you really want to determine what the issue is, open a TAC case so they can work with you over Webex. They can help determine if your unit is bad also. If you have another 2504, I would factory default that, setup the basic for connectivity with one ssid and test.

[patoberli]

I don't know if that is customer visible, but yeah, a TAC might help.

[danailpetrov]

Unfortunately I don't have an active support for that unit so TAC is not an option for me :( 

[patoberli]

Then it starts to get difficult.



Can you output the following please for an affected AP:



grep include "Channel Utilization" show ap auto-rf 802.11a "AP name"



Depending on if you're connected to 5 GHz or 2.4.

[danailpetrov]

Hello,

Here is all the outputs for all the APs. 

The one I am using right now (probably the most) is AP3

Link to Pastebin 

[patoberli]

Radio looks also fine. Honestly I don't know what else could be wrong, besides maybe a faulty WLC or firmware issue.
You might want to try the latest beta version 85mr6, if you haven't already.

[danailpetrov]

Hi gents, me again!

I have again decided to spend some cycles on that annoying issue. I have figured out one thing - upload form my laptop is okay whereas the download (even from the local network) is crap! 

I did the most basic test possible running iperf with UDP (to avoid any latency related issues/TCP) and the result is as follow:

Upload from my laptop to local server: 890Mbps

Download form my laptop from the same server: 25-40Mbps (with loads of drops)

It's just shocking! Check out the results.

upload-vs-download

Do you guys have any idea what could eventually explain this behaviour? I've seen quite a few topics here about slow download/fast upload, but nothing's quite like the issue I've got... I don't thing there is any difference from RF perspective whether the traffic is from/to, but I am opened to any suggestions ... 

[patoberli]

Switch the channel to 20 MHz and test again. If It works fine then, it's most probably a driver issue.
Also 8.5.160.0 was released, you might want to upgrade.

[danailpetrov]

hm, I will try this but will this be the case for every phone/tablet/pc/mac that I have at home? 

To me it seems to me something with WMM but there is only so much I can see about it on 2504 :/ 

very annoying... I will try to manually use one channel only & will let you know.