Using a GPS to perform a Wi-Fi survey

It is important to perform a wi-fi survey so that you can determine not only the perfect place to locate your access point or bridge but to gain an understanding of the channel co-existence challenge you may face.  With wireless access points in surrounding neighborhoods and businesses, you will need to  perform a survey by walking around and mapping out the BSAs (Basic Service Area) of wireless that surrounds you and your organization.

Below is an example of our school’s perimeter.  Matt, Chris and James, students in the Computer Information Technology, class performed a survey using a Microsoft GPS and Vistumbler.  This survey revealed access points and their channels of current wireless at our institution and  includes APs in surrounding businesses and neighborhoods.  These were mapped using Google Earth after exporting their KML file from Vistumbler.

This type of survey allows IT professionals to analyze data exported to ensure the correct channels can be used at their organization.

Miller Goodroe Felts

After exporting the wireless information, you can analyze each access point or wireless device by clicking on it.  Below is an example of the information exported into Google Earth.   Each device shows SSID, Network Type, Mac Address, Channel, Security, Encryption Type, Data Rates, Latitude, Longitude and Manufacturer information.   Analyst using this information can also determine the best placement of wireless devices along with channel information.

ESSID Expanded

Channel co-existence is when access points share channels that are very close to one another.

802.11 wireless on 2.4 Ghz has three non-overlapping channels.  These channels are 1, 6 and 11.  The closer channels are, the more likely interference will take place.  With the amount of wi-fi in use today, IT professionals have to chose between 2.4 Ghz and 5 Ghz and and try to select channels that are not in use if possible.   Professional access points and bridges can also adjust power as necessary.   A dense population can make this very challenging.

If you look at the students’ survey by zooming out to see how many access points can be seen, this is what you are looking at!  Now you can see why site surveys are important at your organization.

Exploded

In addition to this survey, a secondary survey using a spectrum analyzer is very important to search for interference from other sources.  (See our review of the Airview Spectrum Analyzer)

analyzer-software

Channel information (Chart from Wikipedia)

NonOverlappingChannels2.4GHzWLAN-en.svg

Here’s another look at a wireless survey showing vertical lines and signal strength.  (James M. KML survey)

Another view James Miller KML

Network Switches – Avoid Daisy-Chains

When you are networking computers, wireless access points, printers and other nodes in multiple rooms, try to avoid daisy-chaining switches or using small 4-8 port switches when you are in a hurry.  Replace any hubs on your network as soon as you can.

With a hub, collisions can be >20% and utilization can stand at >50%.   By replacing a hub alone, you can reduce collisions to 5% on switches in rooms and <1% in the server room.  Switches help to isolate traffic, relieve congestion, separate collision domains (reduce collisions), segment and restart distance/repeater rules.

Daisy Chaining Switches -what not to do

Real world scenarios may require you to temporarily daisy chain switches.  If you do, test the network and run additional backbones or replace core switches to accommodate more nodes as soon as you can. (remember, replace any hubs in your network)

Daisy chaining

One of many solutions is to run independent lines to the core switch

alternative

Basic tips on optimization of your network -

  • Use stackable managed switches
  • Purchase switches that support
    IEEE 802.1D , IEEE 802.1p , IEEE 802.1Q , IEEE 802.1s , IEEE 802.1w , IEEE 802.1x , IEEE 802.3 , IEEE 802.3ab , IEEE 802.3ad (LACP) ,
    IEEE 802.3ae , IEEE 802.3u , IEEE 802.3x , IEEE 802.3z
  • Use a battery backup on the switches

This is the very basics behind network switch infrastructure.  Managing switches and using the IEEE standards above along with optimizing your network and managing the network infrastructure is important.

Excellent articles on Networking Infrastructure

http://www.lantronix.com/resources/net-tutor-switching.html

http://www.techrepublic.com/blog/it-consultant/only-novices-daisy-chain-switches/

Over-Provisioning and SSDs

Over-provisioning is the allocating of a specific amount of free space on your SSD.  Over-provisioning improves SSD endurance and performance.   Many SSDs are packaged with software that helps the end user install the drive and to plan for OP.  (More advanced drives are doing away with OP).

The SSD controller manages all of the data that is stored on the drive.  While these drives are really fast, data writes are not just placed on the drive.  Data is moved around and the controller on the drive is programmed to use the drive evenly across the NAND blocks.   By moving the data around, the controller can use the free space (OP) to swap information as needed.     This in turn adds life to your SSD.  Always update your SSD firmware, use the manufacturer’s software for OP if your drive recommends it and don’t forget to trim your hard drive.  TRIM allows for the removal of junk or old data.  How? Easy – Open a command prompt (as Admin)

Type the following - fsutil behavior set DisableDeleteNotify 0

Over-provisioning in Samsung Magician’s software.

OP

Always load the drivers – Below is Intel Drivers on my laptop vs. Windows 8 generic drivers

drivers

Windows 8.1 SSD Optimization

If you have install an SSD to Windows 8 or 8.1, and you aren’t sure if the OS is optimized for an SSD. Here’s the fastest way to make sure it is optimized.

Open a CMD prompt as an Administrator
Run winsat formal
Defrag will remain on, that’s right, on. After ‘seeing’ the SSD, this tool (defrag) will become optimize and will trim your SSD.
Of course AHCI should be on, over provisioning accounted for and the proper chipset drivers loaded.

Configuring WDS to extend your wireless network

Want to extend your network and make it more reliable and robust?   

Here’s what you will need -

  • Two routers with the same firmware
    • Preferably Tomato or DD-WRT

Login to the first router.  

In this example, the static number 192.168.1.1 is the Main router.

  • Enable the WAN to match your ISP  
  • Enable DHCP
  • Enable Access Point + WDS  (Picture two below)
    • You must have the same wireless configuration on both routers
      • Enter the MAC address of router two under WDS Link with.

Router 1 no 1

Router 1 no 2

Login to the second router

  • Disable the WAN
  • Disable DHCP
  • Assign the router a static IP address (Below we have given the router .250)
  • Enter Router One’s IP Address for the Gateway
  • Enter a DNS of your choice
  • Make the wireless configuration the same as the first router.  Under WDS, change the drop down to automatic.

Router 2 no 1

Router 2 no 2

With the same settings, you can now extend your network several hundred feet under the right conditions.  Because the SSIDs are the same, once you join one of the routers with a smartphone or laptop, it will seamlessly change to the stronger signal.

With Tomato, you can chain together approximately 12 devices.

Links-

Tomato RAF

Shibby’s Tomato

DD-WRT

Note; The IP addresses and MAC addresses are in a lab environment.

How does it look on a network map?  The two routers are actually connected together.  The switch is the four ports on the back of the router closest to the internet.

Map

Wi-fi takes a long time to find network after computer sleeps

After your computer goes to sleep, do you notice it takes a long time to connect to your wireless router?
slow
There can be several reasons for this.

Here are some tips~

  • Power management on the adapter is enabled
    • Disable in the Device Manager
  • Advanced Power Management
    • Disable under Power Options (Advanced)
  • Bluetooth Interference
    • Disable under the advanced tab on the wireless network card properties
  • Outdated Driver
    • Updated the driver from the manufacturer of the wirelesss chip and not from the computer’s support site
  • Disable the Virtual Wi-fi under the device manager if you don’t use Adhoc

Advanced Power options – Set to Max Performance

advanced wifi

Disable Bluetooth settings

 

Bluetooth

Disable Power Management

 

network power device manager

 

Use the following freeware to see if you have channel interference and to analyze the power in each room of your home or business:

Vistumbler
NetSurveyor
Xirrus

 

Ultimately, reset your network by going to a command prompt as an administrator and type the following:

netsh int ip reset reset.log
netsh int ipv6 reset reset.log
netsh winsock reset catalog
nbtstat -r
nbtstat -RR
ipconfig /flushdns

Restart your computer

See who’s on your wireless network – SoftPerfect WiFi Guard

Want to see who is on your wireless?  SoftPerfect’s  WiFi Guard is freeware that scans your network, both wireless and wired and it also inventories connections on your network.

Before setting up WiFi Guard, inventory your computers, printers, routers, TVs and other devices that use your network.  Get each devices’ MAC address.  Load WiFi Guard and mark each device as trusted.  WiFi Guard’s settings allows you to set a scan interval and to put comments on devices that you know.  In the event a new device is connected to your network, you’ll be alerted.

taskbar

Scanned

Set a scan interval that meets your needs.Settings 

WiFi Guard keeps a history of devices that connect to your network.History

SoftPerfect WiFi Guard