Site Survey Tool - TamoGraph

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System Requirements
Driver Installation
Licensing and Trial Version Limitations
Interface Overview
Access Point List
Floor Plan / Site Map
Plans and Surveys, Properties, and Options Panel
Main Menu
Performing a Site Survey
New Project Wizard
Data Collection
Understanding Survey Types: Passive, Active, and Predictive
Active Survey Configuration
Best Practices, Tips, and Tricks
Survey Job Splitting
Predictive Surveys
Drawing Walls and Other Obstructions
Drawing Attenuation Zones
Virtual APs Placement Methods
Manual Placing and Configuring Virtual APs
Automatic Placing and Configuring Virtual APs
Reconfiguring Virtual APs
Working with Presets
Applying Visualizations
Working with Multi-floor Sites
Mixing Real and Virtual Data
Best Practices, Tips, and Tricks
Analyzing Data – Passive and Predictive Surveys
Selecting Data for Analysis
Adjusting AP Locations After Passive Surveys
Splitting an AP into Multiple Unique APs
Working with Multi-SSID APs
Visualization Types
Signal Level
Signal-to-Noise Ratio
Signal-to-Interference Ratio
AP Coverage Areas
Number of APs
Expected PHY Rate
Frame Format
Channel Bandwidth
Channel Map
Analyzing Data – Active Surveys
Selecting Data for Analysis
Visualization Types
Actual PHY Rate
TCP Upstream and Downstream Rate
UDP Upstream and Downstream Rate
UDP Upstream and Downstream Loss
Round-trip Time
Associated AP
Spectrum Analysis
Hardware Requirements
Spectrum Data Graphs
Performing Spectrum Analysis Surveys
Viewing Collected Spectrum Data
Exporting Spectrum Data
Reporting and Printing
Customizing Reports
Google Earth Integration
Configuring TamoGraph
Plans and Surveys
Plan / Map
Client Capabilities
Colors and Value Ranges
AP Detection and Placement
Visualization Settings
Configuring GPS Receiver
Using GPS Configuration Dialog
Finding the GPS Receiver Port Number
Taking Photographs
Voice Control
Using TamoGraph in a Virtual Machine
Frequently Asked Questions
Sales and Support

UDP Upstream and Downstream Loss

This visualization shows loss of UDP packets from the client to the server (upstream) or from the server to the client (downstream) measured in percentages. Packet loss is applicable to UDP tests only, because in TCP, all packets must be acknowledged and no data loss may occur. UDP loss is calculated as the percentage of data that was lost during transmission. For example, if the server sent 1 megabit of data in 10 milliseconds and the client received 0.6 megabits in 10 milliseconds, while 0.4 megabits were lost en route, a 40% downstream loss has occurred.

UDP loss determines end user experience in audio and video streaming applications, such as VoIP. High loss percentage might cause high jitter and delays in audio and video.

When viewing this visualization, it is very important to understand that high downstream loss is normal. UDP traffic is not acknowledged. This means that the party that sends traffic can send as much traffic as the networking system can handle without “caring” about how much of it will be lost. A typical PC on the wired side of the network (server) equipped with a gigabit adapter can send hundreds of megabits per second. This data will first reach a switch, which might be the first bottleneck, and then the AP, which is almost always a bottleneck, because a typical 802.11n access point cannot send more than 100 or 150 Mbps of data downstream, i.e., to the client. As a result, over 50% of UDP packets might be lost en route, but this is the only way to figure out the maximum downstream UDP throughput value.

Suggested Solutions

When high UDP loss areas are discovered, the following solutions are suggested:

Verify that the actual PHY rate is sufficient. Throughput rates cannot exceed PHY rates; in practice, they are about 50% lower than PHY rates. For example, if the PHY rate in the given area is only 2 Mbps, you should not expect the throughput rate to exceed 1 Mbps. In practice, it might be as low as 0.1 or 0.2 Mbps, depending on other conditions.
Other common reasons for low throughput rates are interference and excessive network traffic. The Signal-to-Interference Ratio visualization available for passive surveys might provide insight into interference issues. Excessive network traffic might be caused either by oversubscription (too many clients per AP) or by excessive network load by some clients. The former can be addressed by increasing the number of APs, while the latter should be verified and handled by network traffic monitoring software.