Wireless Water Cooler

This is a general question regarding on-site testing of an existing infrastructure to assess its suitability for events. I work for a company who develop event apps for conferences and part of our service to clients is helping to assess a venues wireless infrastructure.

 

Bit of background

As the only one within our delivery team who has network experience I have spent the past few months furiously trying to get up to speed with the details of wireless networks to better understand what makes one better than another rather than using the 'gut feeling' approach.

 

The main thing for me was to get a spectrum analyzer (we now have a WiSpy DBx) so I use that to get an understanding of how a venue has set up their wireless infrastructure. Along with that I've been using iperf and Tamosoft's Throughput Test to see what throughput speeds I get through the WLAN.

 

The question

With that in mind what do you guys use to assess what's already in place at a site? What looks good to you when carrying our surveys and what makes you worry?

 

I know this is a big question but any help/advice would be greatly appreciated.

 

Thanks in advance!

 

Davy

A packet capture tool, to see who are your top talkers, and how many retries are in the air as a percentage is important to understand what your wifi clients are doing and if there is any foreign traffic in your environment.

 

You are on the right track with the spectrum analyzer.

 

 

thanks for replying, i have a couple follow up questions:

What capture tool are you using? I've been muddling through with wireshark and a USB NIC in Mon mode and capturing radiotap headers. I'm still learning how to interpret the data. With the captures what would be an acceptable retry rate for you?

For packet capture tools you can look at:

 

* AirPcap

* Omnipeek (check http://www.wildpackets.com/products/omnipeek_network_analyzer )

 

For spectrum analyzers you can look at:

 

* Fluke AirMagnet Spectrum XT

* Metageek WiSpy

 

For Site-survey tools you can look at:

 

* Ekahau

* Fluke AirMagnet Surveyor

 

 

To asses an existing WiFi deployment I would look at:

 

* Signal & noise levels at relevant locations (using site-survey tool)

* Possible non-WiFi interference (using spectrum analyzer)

* AP density for planned use (can it support the number of clients?)

* AP locations (placement in hallways or in rooms etc). How much coverage in overlap is there? How will this impact performance?

* Config:

** Channel distribution + channel widths

** SSID config (security, supported data-rates, number of SSID's, etc)

** VLAN's/IP space (enough DHCP leases to support application? Lease time etc, broadcast filtering yes/no?)

 

That are just some pointers... there's probably a lot more to more to look at :)

thanks for the responses. I've been able to get my hands on trial versions of omnipeek and ekahau site survey. Arian K, thanks for the list to look at.

If you aren't very familiar with taking packet captures Metageek EyePA could be a useful tool that will help visualize what is going on in an existing network.  It can help quickly determine high retries, top talkers, etc.