Shameless Vendor Presentation...Types of Interference Co-Channel Every client and access point on the same channel competes for time to talk. Non-Wi-Fi Non-802.11 devices also need

Shameless Vendor Presentation

Shameless Vendor Presentation

Look Into my Eye P.A.

Intro

Joel Crane, CWNE Sales Engineer at Ekahau Twitter: @Potato_Fi

Darkside of the Room

Types of InterferenceCo-Channel

Every client and access point on the same channel

competes for time to talk.

Non-Wi-Fi

Non-802.11 devices also need time to talk.

Adjacent-Channel

Every client and access point on overlapping channels yell

over each other.

65 7

%@&#!?

Wi-Fi is Half-DuplexOnly one Wi-Fi device can talk on a channel at a time.

Data

ACK

Half-DuplexOnly one device can talk at a time.

Detecting Interference

Wi-Fi Scanning ● Shows what channels

AP’s are using

Spectrum Analysis ● Shows interference

from non-802.11 devices ● Shows 802.11 channel

congestion

Start with the Physical Layer

Use spectrum analysis (Layer 1) to identify and

remove non-Wi-Fi interference

Use packet analysis (Layer 2) to dig deeper into

802.11 congestion.

Spectrum analysis will guide you to the next troubleshooting step.

Non-Wi-Fi Signature

Wi-Fi Signature Heavy Utilization

Questions

● Who is talking slowly? ● Who is talking the most? ● Who is repeating

themselves?

1 mbps

65 mbps

Packet Analysis is Best for...Co-Channel Interference

Packet analysis shows the details about 802.11 congestion on a specific

channel.

Activity from laptops, tablets, smartphones,

and access points

Airtime (Layer 2) Percentage of time that

802.11 frames reserved on the air.

Utilization (Layer 1) Percentage of time that raw RF was detected on

the air.

Utilization vs Airtime

How I know that I’m not wrong

Wireless Frame TypesEach frame type gets a unique color

3 Frame Types: ● Management ● Control ● Data

Wireless Frame TypesManagement Frames: “Manage” stations joining and leaving wireless networks.

● Beacons ● Probes ● Authentication ● Association

Wireless Frame TypesControl Frames: “Control” the RF medium and aid in the delivery of other frames.

● ACK ● Block-ACK ● RTS ● CTS

Wireless Frame TypesData Frames: Carry higher-level protocol data.

● Data ● QoS Data ● Null Data

Airtime Arbitration Process

Packet Analysis with WiresharkDifficult to visualize airtime usage.

Multi-layered Pie ChartsCharts show information in layers.

Network

Access Point

Client

Frame Type

Frame TypesSee what is management overhead, and what is actual data.

Data Frames Data QoS Data

Management Frames Beacons Probes

Control Frames Acknowledgements Block-ACKs RTS/CTS

Demo

Packet Capture Sources

AirPcap Nx ● 2x2 802.11a/b/g/n ● Capture directly in

Eye P.A.

*Other Sources ● Linux ● Access Point ● OmniPeek

*Experimental support in most cases

macOS ● Airtool (duh)

Questions?

MetaGeek Team at WLPC

● Ryan Woodings: @ryanwoodings ● Peter Vomocil: @luminouslx ● Casey Cathey: @Cathey_Fi ● Adam Miedema: @ARMiedema ● Brian Rich: @briantrich

Joel Crane @Potato_Fi