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Occasional Contributor I

Aruba Instant: Client disconnects in a Warehouse environment

Hi 

 

I am hoping for some input on a major 'pain in the neck' problem that involves client disconnects in an Aruba Instant deployment in a Grocery/Ambient goods Warehouse (that is approximately 140m x 110m).

 

Our Aruba Instant Firmware version is 6.5.1.0-4.3.1.3_59179.

 

The main issue is that our Foklift terminals are disconnected numerous times a day (kicked out of their Telnet sessions). The forklift guys are paid on a performance basis, therefore you can understand how upset they get whenever they keep getting disconnected - a lot of the time they have to get the Warehouse Management System Admins to kill off their user session before they can log back and continue to work.

 

To try and recreate the issue, we logon to the Telnet session on the Terminal and run a ping to the default gateway of the wireless clients. A Windows ping from the terminal to the same address is also ran (the Terminal is Windows CE 6). We also watch the Summit radio status and can see that the Terminal has good wireless signal (-55dBm to -65dBm). At apparently random locations, when the issue occurs, we can see that we are still connected to an AP with good signal level (e.g. -57dBm) and signal quality (98-100%).

However, all the pings fail and the Terminal loses its IP address. Sometimes it bounces between a number of APs and finally settles (maybe after 2 minutes or so). The IP address returns on the Summit radio status tab and the pings start to work again. However, by this time our Telnet session has been kicked out.

 

We have been having this same problem since the Warehouse opened in May 2017 (TAC had actually helped us set up the RF in this environment - although it has been changed quite a bit since then due to the on going issues). We have tried updating drivers for the Forklift Terminals with no avail. We have also tried a number of different combinations of channel and power settings. We have tried the Terminals on both 2.4Ghz and 5Ghz bands. We have also tried using only non-DFS 5Ghz channels. This was after reading that there could be a delay when roaming to APs that use DFS channels due to clients only passively scanning channels in the DFS range.

 

On a side note we also have text-to-speech Voice Picking Terminals that we are not getting many complaints about (these units beep whenever they lose signal or are disconnected but usually pick up again themselves, i.e. the users are not fully logged/kicked off). We believe that these devices are having the same problems with but we aren’t getting many complaints due to these devices caching work/jobs.

 

A bit of information about our environment

We have 37 APs deployed in this area (22x IAP-304 & 15x IAP-305).

The 22x IAP-304 APs use external directional antennas (AP-ANT-38) in order to shoot the RF down the 22 aisles in the Warehouse - this AP and External Antenna combination are mounted at alternate ends of each aisles at a height of approximately 4-6m. The aisles are approximately 100m long with 12m high racking at either side.

We have 11x IAP-305 (omnis) mounted at ceiling height (15m) around 3/4 of the way up every other aisle. We also have an additional 4x IAP-305 deployed in a few isolated areas that are not part of the main Warehouse (battery charging, cage rooms etc.)

Note: I can supply a diagram/map if required.

 

Client Devices

50x VoCollect A720 - Voice Picking Devices

15x Motorola MC9090-G & MC9190-G - handheld barcode scanners (Using Fusion wireless drivers)

12x IND 3475 - Forklift Terminals (Using Summit wireless drivers)

9x Honeywell Thor VM1 - Forklift Terminals (Also using Summit wireless drivers).

 

RF Information

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

 

Power: At the minute our power is a bit all over the place since we have been testing. Although this has not made a difference either way, the issue is still happening.

Currently 2.4Ghz – min 12, max 18. 5Ghz min 12, max 18.

Should we look to completely get rid of ARM, i.e. lock down channels and power on all APs? I think it does more harm than good especially in a Warehouse environment (At present RF is constantly changing, there is no stability – this makes it very hard to troubleshoot).

 

Finally, I apologise for the long winded post and I would appreciate anyones input.

 

Thanks

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