Ivan Jun/ 29/ 2016 | 0

When debugging basic WiFi networks sometimes the list of free wi-fi tools will work and sometimes it won’t. The challenges of some of the free wi-fi tools out there is that they don’t collect enough data to get to the root problem of why you are receiving wireless drops or disconnects. Below I will go into some details of our  favorite tools that we use and which free ones really work on advanced WiFi debugging or troubleshooting.

Below is a list of  WiFi tools that we have used and recommended to IT managers and administrators.

1) inSSIDer

2) Wireshark

3) Tamosoft Throughput test

4) Ekahau HeatMapper

5) Kismet

6) Metageek’s list of products (Chanalyzer, Eye P.A. & InSSIDer)

7) Acrylic WiFi Free

8) AirGrab WiFi (for Mac Os X)

9) Cain & Abel

10) Homedale (windows)

11) Lizard Systems Wi-Fi Scanner

12) WirelessNetview (windows) free

13) Netstumbler http://www.netstumbler.com/

14) Airmagnet now Fluke

When using these tools or the first step you should think about before purchasing a costly wifi tool is what are you trying to accomplish or debug/troubleshoot.
When it comes to WiFi there are a couple of major areas you should plot out when debugging or troubleshooting WiFi networks.

Here are some of the top questions one should ask a client or IT team.

1) What kind of WiFi issues are you having? Is it dead spots or holes? Is it potential interference? Is it intermediant disconnects? Or is it radio to AP client compatibility issues.

Fix – Dead spots – See below step 5.

Fix – Interference – See step 4

Fix – Client to AP compatibility –  See step 3

2) If its intermitant disconnects is it cross channel interference? Meaning too many AP’s in your design causing signal bounce and over compensation RF issues?

Steps to Fixing – Tune down your AP’s manually or use your controller to adjust power settings, channels and more. If your working with fast roaming devices such as RF
scanner handhelds that are meant to roam fast in warehouses than take your AP controller off of auto RF and design your network so its in manual RF mode. Controllers
aren’t the smartest or intelligent pieces of software tools.

3) If its a client to AP compatibility issue the first step is make sure both AP and client firmware has the latest software fixes. If you continue to have issues continue to troubleshoot with both client vendor and AP vendor. Make sure you have your site survey report to present to all parties. A site survey report and an interference report with a spectrum analysis is recommended.

4) If its interference than you should either contact an expert in RF Wifi spectrum analysis and get a real spectrum analyzer to test and measure RF interference. This is probably not a tool I would recommend buying because our team has spent a fair bit of money on a true spectrum analyzer. Some RF spectrum analyzers cost in the upwards price of $20,000 for a decent tool.

5) If all your having is WiFi dead spots or dead zones there’s no need to purchase any of the costly tools put use some of the free tools such as Inssider. The best and easiest way to test if you have a dead spot is download install the Inssider and see if the area that you think has a dead zone has no visible Wifi mac addresses
or AP’s. Stand in the zone area your in and see if you get access to an access point or wireless AP that has an SNR of 22+ and/or RSSI of -75dbi.

The first thing to have done or do is to pull out your WiFi/Wi-fi site survey report as this will come in handy when troubleshooting with the vendor of the client  device or AP hardware manufacturer such as Aerohive, Cisco, Aruba/HP or Zebra/Symbol. This avoids finger pointing and lengthy conference calls and wasted time between
who’s fault this is. An AP vendor can view that the first step of your site survey has actually been done. This is your BIBLE that says “the air in your environment is clean”. Without this Bible an AP vendor can easily ask for the report and if no report has been done than one will be needed. Many times the AP vendor will just have
you contact your VAR or resseller for the client RF handhelds or mobile device so you can work with them on the debug process.

At most the AP vendor can assist you with prior cases that were solved but the first thing they will assist you with is making sure your firmware has been updated to the latest version.
Note: if you don’t have a smartnet or maintenacne contract you will not get access to firmware fixes or patches.

On a side note now that margins for hardware are slimmer we’ve noticed that companies such as PSION, Zebra, Honeywell/Intermec and other manufacturers are very strict with free & paid support calls. Its a better way to ensure more streams of revenue for them and to weed out all the freebie calls. We always recommend an annual maintenance plan as they aren’t too expensive. It comes handy when your WiFi hotspot or network needs to be up.

So those are some of the fixes we’ve helped our customers along the 17 years we’ve been debugging wi-fi networks. If the steps above didn’t work and all else have failed I would start with these questions below.

When and where do these disconnects happen?

Its a good recommendation to have the customer write down a log or build a log of each client that disconnects, when it happens and where.

Why – This helps our team figure out if this could be an application issue or host server timeout issue or an ISP issue. If all the devices disconnect at the same time than this is probably not a client or mobile/RF scanner issue. Probably more of a switch related or host/ISP server timeout issue.

When the disconnect happens are there any other devices on the same VLAN or subnet that are disconnecting?

Fix – This is one thing that everyone IT admin or consultant should go through. If its just the wifi devices that are disconnecting and not the wired pc’s than we can rule out a few things.
But lets say you have the same application such as remote desktop or some kind of thin or thick client emulation software such as wavelink, stay-link or telnet client that runs on both mobile devices and wired PC’s. The first thing you should compare is if the wired devices and mobile devices disconnect. If the wired devices
disconnect the same time that the RF devices disconnect than we safely say that this issue might be application or host related or the switch/router. Do a trace again with wireless wireshark analyzer.

If the wired devices stay up and the RF devices disconnect see if all RF devices disconnect.
If all RF devices disconnect than we might have a controller issue or switch issue & host/server issue. All RF devices shouldn’t disconnect at the same time. Its very
rare that we see this. A fix to debug this is run AIR cap px and wireshark to trace the debug.

Some cases that we’ve seen happen that made wifi devices disconnect.

A couple of times we’ve seen viruses on one individual PC send out broadcast floods across that VLAN just sending a bunch of FFFFFFFFFFFFFFf’s that clog the network.
All users on the floor should not be able to operate because of the flood.

Another issue we’ve seen is one machine creating a backup of the entire network also causing broadcast floods and halting the network.

Sorry as I did go a little off topic with the free and paid wifi tools but those are just some questions that I get asked on a daily basis.

Many of my favorite tools that we use that are free when doing a general walk around is Inssider and netstumbler or Cisco’s version of the free analyzer that comes with their radio card.

When doing a more complex troubleshooting session we prepare for at least a day onsite and use Fluke’s wireless tools, RF spectrum analyzer , Airmagnet analyzer and aircap px with wireshark tracing. It also does help if your using enterprise wireless access points such as Meraki as in the Meraki dashboard or cloud you can filter on some of the top talkers or top bandwidth hungry users that could be causing slowness in your RF network. We use and recommend Meraki MR32’s.

And not to forget I would recommend never to channel bond your wifi network unless you have all mobile clients streaming for bandwidth heavy applications. If you have a mixed environment of RF low bandwidth clients and heavy bandwidth clients I would just recommend staying with MHz channel and don’t channel bond up to 40MHz or
more. Remember most clients internet pipes are below  10 Mbps so there’s no point in channel bonding to get internet traffic of up to 300 Mbps if your pipe is only so  small. Unless your data is coming from internal and you really need to stream or pull that internal data than yes channel bond in non mixed client design is ok.
When you channel bond on a small non overlapping network you face more potential for your overlapping channels to overlap.

To contact us for a site survey quote locally in Toronto Canada visit us at http://www.sitesurveypros.com

We also have technicians across North America who are under Site Survey Pro’s that follow the same standards that we use locally. All survey kits from SSPRO’s match what will be deployed in your environment. For example if your going to be deploying a Cisco network we will survey your building with a Cisco radio card or AP. We carry survey kits for Cisco, HP/Aruba, Meraki, Aerehive and more.

Ivan
Author: Ivan

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