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Occasional Contributor I

Aruba 270 / Datalogic Scanners

Morning All,

 

I hope someone can help or guide me a little.

 

I have up a Aruba 270 which is working ok , this is soley used for 6/7 handheld scanners (Datalogic Memor X3).

 

I am having a few issues with the range and the scanners dropping connection, it is in a factory environment but I am fairly new to this.

 

Firstly I am not sure which band to be using ? on the scanners I have these options (Memor X3, 802.11 a/b/g/n).

B Rates only

BG Rates Full

G Rates only

A Rates only

ABG Rates Full

BGA Rates Full

GN Rates Only

AN Rates only

ABGN Rates only

BGAN Rates Only

BGN Rates Only

 

What would be the best setting to use for these on both the AP and the scanners ? Sorry for being a little vauge but im quite lost on this.

 

I have attached a few screen shots from the Aruba Instant software.

 

If anyone could take them time to help I would be very grateful !!!

 

Thanks

B

 

MVP

Re: Aruba 270 / Datalogic Scanners

Very wide topic, I'll try to provide a few useful pieces of info on the subject. Most of this information is general in nature,  based on field experience, and does not benefit from input from any given manufacturer of such 802.11 clients. Details of model, firmware may vary - all appropriate disclaimers apply.

 

Looking at the data provided, a few items that stand out:

 

- 802.11d/h not enabled

- too many 5Ghz channels

- High number of neighboring APs

- VHT disabled in 5Ghz

- band steering - use balance-band only if coverage is very carefully calculated - recommend "prefer 5Ghz"

- AP power levels at default,

 

 

 

1. If the devices can use 5Ghz, and there is sufficient coverage in 5Ghz to provide the usual ~ -63dBm primary coverage, lock the SSID to 5Ghz only.

 

If 5Ghz coverage cannot be achieved, lock the SSID to 2.4ghz to at least elminate band-hopping.

 

2. Limit the number of channels to a maxumum of 8 channels. If the deployment is indoor, recommend non-DFS channels 36-48 if possible.

consider the newly allowed UNI-III non-DFS channels which are limited to ~13dBm power levels, but this might be acceptable depending on AP mounting and coverage.

 

Some devices can only handle the 1st 8 (approximately) APs heard to build their potential AP table. This means if the device hears 16 APs, it may take the optimal close APs, may not. Ideal is good primary, secondary and tertiary coverage. a few good choices, instead of many potentially sub-optimal choices.

 

In any case, reducing the number of channels in 5ghz may help.

 

3. 20Mhz wide (this is done)

 

4,. Enable 802.11d/h - this is required for DFS channels, and will help the device know the correct channels and allowed power levels. Will also provide the client with a bit more info with which to make sensible decisions. Some scanning devices require 802.11d

 

5. if 2.4Ghz will be used , recommend non-overlapping channels, 20Mhz wide

1,6,11

1,6,13

etc..

1,6,11,13  - yes, this is not overlapping, but can be a good choice during initial deployment to 

decide whether to use 1,6,11 or 1,6,13  if 13 is allowed in the region.

If ARM sets APs on 13 instead of 11, take a look and see why 11 is not a good choice.

 

6. check actual ARM-directed power levels, the APs should settle at reasonable values between 9 and 127 EIRP
Use the IAP dashboard, sort on "channel busy" or "utilization" if high radio utilization is seen despite no clients, the power is likely too high.

 

At the same time, APs busy with high TX rates might be unecessarily flooding broadcast and multicast - check the SSID "broadcast-filter arp" parameter. set multicast-optimize on (DMO only if required)

 

Based on the AP mounting scheme, a typical power setting for APs that are around 10m apart (path loss around 90, 12-15 EIRP

2.4Ghz should be 6dBm lower than 5Ghz

 

7. Many summit and other chipsets struggle with 11n and spatial diversity

recommend a careful test using csd-override - this will mean frames will be sent to such clients on one chain. test, change, and test again.

 

 rf dot11a-radio-profile

csd-override

 

8. Ensure device  drivers are up to date

9. Ensure device configurations are uniform and consistent

- do not fix channels, rely on 802.11d (world mode?)

- if configurable, set sensitivity levels reasonable based on coverage.

 

10. look carefully at coverage/data rate balances - some scanner devices nearly require lower data rates. this is really a design question - the Aruba "small cell" design with high density of AP mounting, low power levels and only high data rates may not be optimal for this environment. 

 

My advise - set the device on a table within good range of an AP, test

continuous frames to/from the client over a period of time, frame loss and 802.11 retries/drops should be reasonable for an SNR > 35.

 

If this test looks bad, roaming will likely not work well either.

 

If disconnects can be reproduced stationary, the following data is helpful:

 

show ap debug client-table

show client

show ap association

show ap debug radio-stats

 

Important is to differentiate between 802.11/RF issues and higher layer problems such as DHCP, or even IP connectivity.

 

Hope this helps.

 

 

 

 

 

Shawn Adams
Aruba Networks Customer Advocacy
Occasional Contributor I

Re: Aruba 270 / Datalogic Scanners

Wow, thanks for such a great response, so very helpful !

 

802.11d/h not enabled - Done

too many 5Ghz channels - Changed 

 

VHT disabled in 5Ghz - Not sure what this is or how to change it?

 

check the SSID "broadcast-filter arp" parameter. set multicast-optimize on (DMO only if required) - Again not sure what this is or how to change it?

 

Out of the list what would be the best channels to set the readers too ? Sorry i really am new at this, the list of AGBN full type settings?

 

Again I really cant thank you enough for you help !

 

B

 

MVP

Re: Aruba 270 / Datalogic Scanners

Rule of thumb, the defaults are a pretty good place to start.

 

To answer the specific points listed, see attached PDF. The Instant User Guide and CLI Reference Guide cover these parameters.

 

In the IAP under the SSID configuration, there is a checkbox to enable/disable VHT (also called 802.11ac) By default, this is enabled, if the APs are 11ac capable, 802.11ac will be operational.

 

In the SSID configuration panel, there is a parameter broadcast-filter.

ARP means ARP frames will be sent over the air 802.11 unicast at higher rates, more efficient.

 

This also means broadcast and multicast will not be floooded, saving airtime.

 

The DMO parameter causes desired multicast streams to be converted to unicast, and thus sent to 802.11 clients more efficiently. Set this only if multicast streaming is in use.

 

multicast-optimization simply transmits multicast at a reasonable higher rate, not the default lowest basic rate - again - saving airtime.

 

The default 802.11g band channels are 1,6,11 - non-overlapping.

 

I'd suggest setting the 5ghz channels 36,40,44,48,52,56,60,64 with the associated + channels, 40Mhz Channels are set per radio, so this will affect all SSIDs on the radio.

 

Summary:

Disable 80Mhz operation

5Ghz will have 8 channels, 40 Mhz

2.4Ghz will have 3 non-overlapping 20Mhz channels

 

If you can reproduce specific symptoms with the scanners, or any other device, I'd advise to gather the IAP VC tech-support and open a support case under your support contract.

 

For client specific issues, as an addendum to the tech-support, there are a few focused commands to be run repeatedly during the failure.

 

# 802.11 connectivity problems

show client debug

show ap association

show ap debug client-table

 

# for IP related issues

show datapath user

show datapath session

 

The beauty of 802.11 is learning the complexity, we all started somewhere. I hope this helps.

 

 

Shawn Adams
Aruba Networks Customer Advocacy
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