Wireless Access

Hi, 

I have a customer (school setup) on AP 515 on instant mode running firmware version 8.5.0.5 (go to version). They have been experiencing random wireless disconnects. This happens to users who are static in their locations or to users who move to another area, open their laptop and failed to connect to the wireless. Usually, a manual off/on wireless resolves the problem or disconnect and reconnect the SSID. 2 behaviors were seen:

(A) A few users in the same room could be affected at the same time. A globe with no entry icon instead of wireless icon is seen at the bottom right on the toolbar. Failed to ping to default gateway. 

(B) Only random users are affected

They had 80MHz enabled previously and had about 5 SSIDs enabled. I have disabled 80MHz and support only 40MHz on 5GHz radio and consolidated the SSIDs to 2. Tx power settings were configured as follows: 2.4GHz min 6 max 9. 5GHz min 15 max 18

The school had upgraded from previous IAP225 on ver 6.x last Dec. According to them, they did not experience similar issues before the AP switch.

I had previously seen this behavior before at another school with same AP model but it was on firmware version 8.6.0.0. We downgraded it to 8.5.0.5 and the problem was resolved since. However, success is not seen for this school. 

Appreciate your advice. Thanks.

Attachment(s)

client screen capture.pdf   82 KB 1 version

Do you have encryption enabled on this SSID?

Hi, yes. wpa2-aes. Authentication to CPPM. Sorry, should have included some config. 

I have attached extracts of the configuration. 

Attachment(s)

APconfig extract.txt   1 KB 1 version

Thank you.

What is the density of those access points?  What are the walls made of,?  How many a cess points can you see in a room?  Is broadcast filtering be enabled on All SSIDs?

Hi,

In general, it would be safe to say 1 AP per classroom. Unfortunately this was the case when we went in. 

Regarding the IT room where the client was, it is standalone on the ground floor. There are classrooms in the levels above. I have attached spectrum analysis done in one of the staff area in L1 and L2 of new building and IT room. There is also a cross-section diagram of the building where IT room locates. 

In the new building, the classrooms are separated by glass wall. The older buildings would be separated by dry wall.

There's only 2 SSIDs broadcasting. This and guest (via guest captive portal). Config for the guest SSID as follows:

wlan ssid-profile vilxx_guest
enable
index 2
type guest
essid vilxx_guest
opmode opensystem
max-authentication-failures 0
vlan 128
auth-server clearpass
set-role-pre-auth guest_logon
rf-band all
captive-portal external profile V-Guest
dtim-period 1
broadcast-filter arp
radius-reauth-interval 240
radius-accounting
radius-interim-accounting-interval 10
g-min-tx-rate 6
a-min-tx-rate 18
multicast-rate-optimization
dmo-channel-utilization-threshold 90
local-probe-req-thresh 0
max-clients-threshold 64

I know there's co-channel interference in new building. In IT room, it looks clean.

Attachment(s)

Spectrum results.docx   1.22 MB 1 version

It should be noted what band/channel the client is on when there are drop outs:

"netsh wlan show interface" on the Windows Commandline

Questions:

wlan ssid-profile Vilxxx
 enable
 index 7
 type employee
 essid Vilxxx
 opmode wpa2-aes
 max-authentication-failures 0
 auth-server clearpass
 auth-survivability  <----Any idea why this is there?
 rf-band all  <-----If all enterprise clients support 5ghz, consider making this 5ghz only
 broadcast-filter arp
 radius-reauth-interval 600  <---Do you want your enterprise clients forcing reauthentication every 600 seconds?  That could put additional strain on the ClearPass server.

wlan ssid-profile vilxx_guest
enable
index 2
type guest
essid vilxx_guest
opmode opensystem
max-authentication-failures 0
vlan 128
auth-server clearpass
set-role-pre-auth guest_logon
rf-band all
captive-portal external profile V-Guest
dtim-period 1
a-min-tx-rate 18  <---That would be a little high unless you want clients to roam more frequently.  Was this intentional?

Hi, 

Auth-survivability: They want authenticated users to remain authenticated though (next point: re-auth interval) it may be unnecessary given the long re-authentication interval

Re-authentication interval: 600 min

Rf-band all: The students are allowed to bring their own laptops so there is no telling if all the laptops are 5GHz or not.

Sorry, guest configuration was dated. Below is fresh from the oven.

wlan ssid-profile vilxx_guest
enable
index 3
type guest
essid vilxx_guest
opmode opensystem
max-authentication-failures 0
vlan 128
auth-server clearpass
set-role-pre-auth guest_logon
rf-band all
captive-portal external profile V-Guest
dtim-period 1
broadcast-filter arp
dmo-channel-utilization-threshold 90
local-probe-req-thresh 0
max-clients-threshold 64

---

@simon168 wrote:

Hi,

In general, it would be safe to say 1 AP per classroom.

---

To be clear, there is nothing wrong with 1 AP per classroom unless there are maybe 35 students  or more in there.

Do you ever get to look at what the RF utilization is for access points on the front page?  That would indicate if things are truly congested in realtime.

I cannot interpret that spectrum graph, because I cannot tell which APS are from the business and which are foreign...

Hi

Yes, I have looked at the utilization of the AP under Dashboard. I was focusing on the ITroom AP since I know there are reports of wireless drop out there. There are typically about 19 connected clients. Noise level for 5GHz would sometimes increase to about -83 to -87. Utilization was less than 10%.

Regarding the spectrum, the APs starting with D0.15 are the school's AP. I have indicated other SSID where possible especially if it is interfering. This SSID is advertised by external AP.

I have had SERIOUS problems with IAP-515 AP’s and random dropouts - so much so I had some exchanged to test for productionseries issues and had weeks of TAC support running.

I don’t think it is official in any capacity, but there is a Radio bug in some of the 515’s, and that is fixed with the release of FW. v8.6.0.2 (Note: There’s nothing in the release notes about it).

I tested and worked on the issue for weeks and weeks, and tried everything on 8.5.x.x and 8.6.0.0 + 8.6.0.1. When 8.6.0.2 was released the problem vanished and it’s been smooth sailing since.

I thought that I was the only one with the strange issue.

I replaced a 315 with a 515, and my performance dropped like a stone.

I've been testing different scenarios for months, and using the latest 8.6.0.4 firmware on my entire cluster and still have strange drops.

We have a lab with only 515's, and it constantly has issues with devices connecting and dropping.

Is there a hardware version change yet?

We may have a different issue here...

Have you opened a Technical Support case?  They might be able to help narrow down your issue.

Response to cjoseph...

A TAC case was opened initially when we couldn't stabilize the site.

This site had only 1 515 (lab) and nothing else.

The test device had no previous isses connecting either to 2.4 or 5 GHz.

TAC eventually said there was nothing on the device, and indicated that there was an 'environmental' issue and reccomended that all RF setting be set to 'MAX'

We decided to setup a second lab and modify the settings to get the best results.

The initial poster (OP) mentioned that they had dropouts.  A second poster in this thread mentioned a radio issue they believed is solved by upgrading to 8.6.0.2.  You mention a performance issue.

If you want to post your issue and your possible solution, you should use a separate thread, because you are diluting the Op's efforts to get to the bottom of their issue. 

The issue was dropouts, performance may have been a poor choice of description.

My issue was the same as the OP.

Do you have any tips that can help the OP?

What I've done...

- Not set the radios to MAX

  Use the 12~18 setting or perform a wifi survey

- Disable High Efficiency on the SSID

- Review the ARM settings.

- I've enabled 5GHz Wide Channel with 80MHz support

I'll probably install the 8.7 code and test this, as the issue still exists, but not as dominent.

Can the OP provide a sample of devices that are affected?

In my testing, Android and Windows 10 devices had the most issues.

Hi all

I have configured a new SSID identical in configuration to the one in question and put it into a zone and assigned only the IT AP into that zone so that it is the only AP advertising the new SSID. The new SSID has 'HE' disabled. All other configurations remains. 

Customer had a run for two days on the new SSID and did not report the wireless drop whereas it was happening rather frequently. 

We have proceeded to disable HE on the production SSIDs and are now in monitoring phase (just did it yesterday). 

So far, the devices affected are Win 10 machines. Some are AX capable while others are not. Having said that, this is a school environment and hence, personal devices (Android/IOS) sometimes aren't on the network long enough to be affected.

Will update the status at the end of the day.

Cheers

Thanks for sharing. I will note that. I have reviewed the release notes from 8.5.0.6 to 8.7.0.0. Found a known issue with AP-515 but the symptom wasn't exactly matching.