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Occasional Contributor I

Aruba Instant: Client disconnects

We are having a problem whereby Windows CE clients (multiple versions and multiple Vendors) are losing network connectivity . This happens on both 2.4 & 5Ghz bands when they seemingly have decent wireless signal (we have tried both bands to no avail).

 

Has anyone came across this with Aruba Instant firmware versions 6.5.1.0-4.3.1.3_59179 and below?

 

The client devices are forklift terminals using Summit wireless drivers and Motorola 'voice picking' terminals using Fusion wireless drivers.  These devices are used in a Warehouse environment - the fork terminals are kicked out of their telnet sessions while the Motorola voice units timeout/beep/get kicked out of their current picking tasks. 

 

Some of the settings that we are using:

Broadcast Filtering is set to All

Multicast transmission optimization is enabled

Dynamic Multicast Optimzation is enabled

DMO Channel utilization threshiold 90%

Transmit Rates – Both bands 12-54

DTIM interval – 1

Band Steering: Prefer 5ghz

Airtime fairness: Fair access

Client match: enabled

Cm calculating interval: 10 secs

Cm neighbour matching %: 60

CM Threshold: 5

SLB Mode: Channel

Client Aware: Enabled

Scanning: Disabled

Wide channel bands: None

 

Can anyone advise if there is anything else I can try? I have had multiple calls with TAC who either mess around with power levels, firmware versions or disable/enable client match but my problem has never been solved. I have also been told contradicting information by TAC that if Client Match is enabled but 'Scanning' is disabled then Client Match will not work. 

 

I'm starting to worry that I will always have these issues with Aruba Instant in a warehouse no matter what, as opposed to using a controller solution.

 

Just to confirm, this is happening in two separate warehouses that are both running Aruba Instant and both connecting to two separate Warehouse Management Systems.

 

Thanks

 

 

 

Guru Elite

Re: Aruba Instant: Client disconnects

Warehouses are the most difficult environments to put wifi in, because there are so many things that can cause interference and so many variables.  Typically those things are observed, measured and mostly dealt with on install.  After installation, product and equipment can be moved and change the RF environment considerably, causing issues that did not exist before.  Forklifts add another dimension, because they are always moving, so roaming is also a consideration.  Lastly, voice requires the highest quality signal, and is delay sensitive, so an environment that is less than perfect will manifest itself in voice picking.   Those are some of the reasons why it is difficult at times to deal with warehouse issues over the phone.

 

With that being said:

 

- What kind of access points do you have deployed?

- How high are they mounted?

- How far apart are they mounted?

- How many SSIDs do you have deployed?

- Do you have individual clients running on both bands?  (Is the voice picker configured to operate on both the 2.4ghz and the 5ghz band)?

- Are your drivers up to date on your scanners and voice pickers?  Many of those devices were not deployed initially on 802.11ac access points and updated drivers allow better interoperability.

- Do you have any non-default settings on your SSIDs?  (I see you cut of the lower transmit rates...why?)

- If you disable scanning, APs will not be able to scan other channels to mitigate interference.  Turning off scanning is typically a troubleshooting step to make the environment more stable, if the access points have already chosen optimal channels.

- Client Match depends on scanning to find clients that are nearby, but not on their same channels.  You should be able to operate your network without client match, in principle.

 

 

 



Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

Occasional Contributor I

Re: Aruba Instant: Client disconnects

Hi Colin

 

I greatly appreciate your reply.

 

I should have made myself more clear on the voice picking terminals. These terminals are not actually true voice over wifi. They are really text-to-speech over wifi.

Basically The Warehouse Management System sends data to the terminal that is displayed on the screen but also translated into speech -that is heard through a headset that is attached to the terminal.

The user then uses phrases and commands (that each user has to train when initially getting setup for use) that are then sent back to the Warehouse Management System. When there are problems with the connection to this system, the user will hear a number of beeps that are then followed by a comms error on screen. This then causes the user to get kicked out of their picking task, This causes alot of frustration for the guys as they are paid on a performance based pay scheme, therefore these interruptions/disconnects are affecting their pay packet.

 

The forklift terminals are bit more simple. Basically they logon to a Telnet session either using 'RFTerm' (on the Honeywelll Thor VM1 units) or with TelnetCE (on the IND3475). Alot of the time, the screens they are in can lag or else they can be completely kicked out/disconnected from their telnet session. The forklift driver then has to contact the WMS System Admin to kill their session so that they can login again and continue their work.

 

Just a note:

Warehouse 1 - is the only place where we use the Forklift Terminals

Warehouse 2 - is the only place where we use the "Text-to-speech"/Voice Picker Terminals

 

- What kind of access points do you have deployed?

Warehouse 1

A mixture of IAP304 (with directional antenna - AP-ANT-38) and IAP305 (omni). There is an IAP304 mounted on every aisle in the Warehouse - these are staggered so that they are at opposite ends every aisle (x22). The IAP305s are mounted in the middle of every other aisle (x11).

 

Warehouse 2

A mixture of IAP304 (with directional antenna - AP-ANT-38) and IAP305 (omni). There is an IAP304 mounted on every aisle in the Warehouse - these are staggered so that they are at opposite ends every aisle (x9). There are x2 IAP305s in the middle of the warehouse although we currently have these set to spectrum monitor mode.

Note: There are sections in this Warehouse/Cluster, dry goods and the freezer. I've only given you the AP numbers and information for the dry goods area as this is the area I have been focusing my testing and troubleshooting in.

 

- How high are they mounted?

Warehouse 1

IAP304 - at one end 6m high at the other end approx. 4m high

IAP305 x11 - approx. 50ft/15m high

 

Warehouse 2

IAP304 - x5 at one end approx. 3.4m high. x4 at opposite end approx. 5m high

 

- How far apart are they mounted?

Warehouse 1

IAP304 - approx. 12m apart

IAP305 - approx. 12m apart

 

Warehouse 2

IAP304 - approx 12m apart

IAP305 - approx. 18m apart

- How many SSIDs do you have deployed?#

Warehouse 1

1 x SSID in Cluster

 

Warehouse 2

1 x SSID in Cluster

 

- Do you have individual clients running on both bands?  (Is the voice picker configured to operate on both the 2.4ghz and the 5ghz band)?

Warehouse 1

No, currently we are running the Forklift Terminals on 2.4ghz band only - 802.11g. I have actually tried running these on 5ghz band - 802.11a - but we just have the same issues.

 

Warehouse 2

No, the "Text -to-speech"/Voice Picker Terminals are all running on 5ghz band - 802.11a.

 

- Are your drivers up to date on your scanners and voice pickers?  Many of those devices were not deployed initially on 802.11ac access points and updated drivers allow better interoperability.

Yes, we have updated the drivers of the client devices to the latest possible versions.

 

- Do you have any non-default settings on your SSIDs?  (I see you cut of the lower transmit rates...why?)

The lower rates were trimmed I believe to promote better roaming. This was done by TAC when we had contacted them during our initial setup phase of Warehouse 1. We then carried this on when we setup Warehouse 2.

As regards non-default settings - the following were also set:

Broadcast filtering to All

Multicast transmission optimization to Enabled

Dynamic multicast optimization to Enabled

DMO channel utilization threshold 90%

802.11r, 802.11k & 802.11v are all unticked.

 

- If you disable scanning, APs will not be able to scan other channels to mitigate interference.  Turning off scanning is typically a troubleshooting step to make the environment more stable, if the access points have already chosen optimal channels.

Scanning is off in Warehouse 1. But on in Warehouse 2. This hasn't made a difference either way.

- Client Match depends on scanning to find clients that are nearby, but not on their same channels.  You should be able to operate your network without client match, in principle.

 

On another note in Warehouse 2 we have completely locked down (admin assigned) channels and power on APs (All APs are either channels 36 , 40, 44 or 48 - non-DFS channels and are either set to 15dbm or 18dbm). When ARM was enabled we thought it might be making too many changes making the RF environment unstable - I admit this is a longshot, but I would try anything to stop these disconnects. 

 

I can upload maps if this helps at all.

 

Thanks

 

 

 

 

 

 

 

Guru Elite

Re: Aruba Instant: Client disconnects

Have you used a handheld with Aruba Utilities from the Google Play Store to see how many access points you can see in any area and at what signal strength?  That might give you an idea of your coverage from the handheld point of view at your current transmit power.

 

You might also consider re-adding more non-dfs channels to your allowed channels to avoid interference.  APs on the ceiling can see each other much better than the clients and that might be a source of contention if you are not spreading your channels out more.

 

In the warehouse, can product get all the way to the ceiling, or not?

 

You might want to try pinging a device from a wired endpoint and walk some rows and see where and when it might get disconnected or lose alot of pings, to get an idea where you problem lies.

 

Have you seen the PDF of the presentation here?  http://community.arubanetworks.com/t5/Airheads-Breakouts/Hostile-Environments-Wireless-LAN-Design-for-Warehouses/ta-p/247147

 

 



Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

Occasional Contributor I

Re: Aruba Instant: Client disconnects

Hi Colin

 

I think I'll download the Aruba Utilities from the Play Store and see if anything stands out although I do use inSSIDer when looking at power levels etc.

 

We have only started using solely non-DFS channels (36, 40, 44 & 48, i.e. UNII-1 Domain) as of last week in Warehouse 2. We tried this because we noticed that every now and again a client would get a ping response time of 2000ms or more when using the DFS channels and thought that this might be causing our disconnect problems. We had read that clients can only passively scan DFS channels which can take 4 times longer than normal and could be causing these high response times.

When we changed Warehouse 2 to non-DFS channels only we noticed that we didn't get these intermittent high ping response times anymore, although the disconnect problem is still on-going so it really made no difference.

I don't think we are able to use any of the higher non-DFS channels (UNII-3) because we are in the UK, therefore I believe we are stuck with channels 36, 40, 44 & 48 only (as far as non-DFS channels go).

 

As regards the APs on the ceiling. We actually have the 2 IAP305s in the middle of the ceiling in Warehouse 2 set to spectrum monitor. And we are just using the IAP304s that are shooting down each aisle.

 

Yes, product on the shelves/racking can get pretty much as high as the ceiling.

 

I will try the pinging the wireless client device from a wired endpoint and see what are response times and ping rates are like and I will report back.

 

And thanks, I have read Charlie Clemmers presentation and also the one by Chuck Lukaszewsk.

 

Are there any logs that you think might be useful for me to look at when we experience these issues? One that I could maybe look at in real-time to see if anything jumps out?

 

Also, how can you tell if you have too many APs or the power is too high? Is there anything within the CLI I can look at to determine this. When we do a walk around, our RF looks good, so it's hard to identify if the issues we are having is because of power or lack of, or because of channel quality, contention etc.

 

Thanks

Paul

 

 

 

 

 

 

 

 

 

 

 

Guru Elite

Re: Aruba Instant: Client disconnects

Warehouses can have lots of square footage, so it is very hard to troubleshoot issues.  It is most important to find out where the most of the complaints exist, and focus on those limited set of areas, to try to make progress.

 

Using Aruba utilities on an Android Handheld is mainly to get an idea of how your other handheld devices see how many access points.  If they can see more than two access points on the same channel, that *might* be a source of contention.  Two access points on the same channel that can be seen is not a dealbreaker, but look on the Instant GUI to see what percentage utilization each AP has on its bands to see if you have more than 25% utilization.

 

You should enable all the lower rates to get an idea of how the devices roam at the current transmit power and see if they roam smoothly, or do they drop packets even when they are not roaming.  Dropping a packet or two during a roam is not a dealbreaker.  If you see your client going past an AP and not roaming to it, your overall power might be too high.

 

If you have site survey software, you should do a limited survey of the areas determined to have the worst issues, to see what access points are really providing coverage in those areas and if they are part of the problem.

 

Lastly, you should consider having an expert come out to your facilities to see if there is a hidden problem with your RF (interference) or if your access points or antennas could be mounted wrong and providing the wrong coverage.  Tracking down an issue that has multiple causes is very difficult without actually seeing the space.



Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

Occasional Contributor I

Re: Aruba Instant: Client disconnects

Hi Colin

 

Can you explain what the message "Auth failure......Reason AP is resource constrained" means? I've read that this could mean that the AP has reached it's max client threshold (this is very unlikely because this is set to 64 and we were the only client on the AP at the time).

 

This may be completely unrelated to the disconnects we are experiencing, but I keep coming across the same message when I am looking at the logs in Support tab on Instant (ap log all) and it would be good to rule this out so that I'm not focusing on this too much.

 

Thanks

Paul

Guru Elite

Re: Aruba Instant: Client disconnects

That is a generic message the AP sends if it is beyond capacity when it wants a client to go somewhere else.  It also could be send as the result of client match load balancing.  You can turn off client match to see if those messages go away.



Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

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