What is packet loss? A definition and more
Packet loss occurs in networks when data packets are lost during transmission or individual data packets arrive late at their destination. Before being sent, data is packaged into several layers. These packets travel through a variety of different hubs (copper cables, fiber optics, wireless, etc.) to reach their destination. In these hubs, TCP packets get lost or become delayed. Once sent, each packet is marked with a timestamp.
This value specifies the amount of time the sender must wait before obtaining a confirmation of receipt. If a packet gets lost or is delayed, it eventually “times out.” When this happens, a new packet is sent in its place. This is known as a retransmission timeout (RTO). The result? Data packets arrive late and performance suffers due to this latency. So, a stable internet connection without any network congestions has as few packet losses as possible.
Why perform a packet loss test?
Packet loss is accountable for many network problems, especially in wide area networks (WANs) and in wireless networks. A packet loss test helps to establish whether network connectivity problems, slow network speed, or low-quality VoIP connections are caused by UDP packet loss.
PRTG is a powerful network monitoring tool which not only helps you to check lost packets, troubleshoot wireless packet loss and UDP packet loss issues, but can also be used to calculate bandwidth, check the availability of network devices, to monitor network utilization, scan IP addresses, and to keep track of internet and network performance. Its flexible alerting options allow you to determine exactly when and how you want to be alerted of issues that require your attention.
PRTG performs a reliable UDP packet loss test using the built-in QoS (Quality of Service) One Way sensor, which takes its measurements by sending UDP packets between two remote probes. Apart from measuring lost packets, the QoS sensor monitors parameters such as VoIP jitter, duplicate packets, packet delay, and Ethernet latency.
Measuring the connection between two PRTG probes
Example: To measure packet loss on the path between your PRTG Server and your server room, install a PRTG remote probe on a Windows computer in the server room and connect this probe to the PRTG Server. Then create a QoS (Quality of Service) One Way Sensor on the probe that is set up on your PRTG Core Server.
In the sensor settings, select the probe in the server room as the destination. PRTG will automatically send data packets back and forth between the two PRTG probes, thereby monitoring the quality of the connection (which includes a test for packet loss). The sensor indicates the length of time data packets need to reach their destination, as well as the delay and packet loss rates. You can also measure the packet loss rate between two remote probes and thus – by setting up both Windows systems near the endpoints of the data route you wish to monitor – test a random data connection for packet loss.
Using a PRTG QoS Reflector
The Reflector is a Python script that sends data packets from endpoints back to PRTG. The script can be used on any (Linux) computer (even a small Raspberry Pi), allowing you to bypass the need for a Windows computer and a remote probe.
You therefore do not have to create a remote probe for this test. The principle, however, remains the same. You’ll need to define the two endpoints of a data route to obtain QoS measurements and test data for packet loss. As with the first test, this test allows you to extract data which can be used to analyze the quality of your connections in greater detail. Learn more about the QoS Reflector here.
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Isolating and fixing packet loss: 3 sensors to help you get started
Use the Ping Sensor to measure the availability of your devices and to calculate packet loss as a percentage.
Use the Cisco IP SLA Sensor to measure the packet loss rate on your Cisco devices.
The QoS (Quality of Service) One Way Sensor lets you monitor network paths, and thereby measure and reduce packet loss. This sensor is also included.
3 examples of packet loss
Packet loss in routers and switches
Routers and switches are sometimes a liability, for bottlenecks can emerge during the transmission of data when hardware is old or missing important updates. Example: If a switch transmits too many data streams at once, it can quickly reach its capacity limit. This leads to delays in packet switching, as well as jitter.
Video conferences: Packets get lost
For many companies, video conferences and internet telephony are a vital part of everyday work. This is especially true in international companies or firms with branches in many different locations. Packet loss can easily occur during video conferences and VoIP as data is transmitted in real-time. The above-mentioned sensors will help you quickly identify bottlenecks in your network.
Your Citrix Cloud keeps freezing up? SAP applications still run, but only barely? Packet loss and delays can impact the performance of important applications. It is especially frustrating when employees neglect to inform the IT department of such delays, and instead grudgingly accept having to work at a slower pace. In such cases, the productivity of the firm suffers considerably.
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PRTG in a nutshell
PRTG monitors your entire IT infrastructure
Use PRTG to monitor, for example, network traffic, applications, bandwidth, cloud services, databases, virtual environments, availability & uptime, ports, IP addresses, hardware status, network security, web services, and much more.
PRTG supports the most important technologies
Monitor your network for example via SNMP, flow protocols (NetFlow, jFlow, sFlow, IPFIX), SSH, WMI, or ping. PRTG also supports technologies used in Industrial IT & OT environments, such as OPC UA, MQTT, or Modbus. Use the powerful PRTG API for custom integrations (for example via Python, PowerShell, or REST).
PRTG can be used for any operating system
Download and install PRTG Network Monitor on a Windows system or use our cloud-based product PRTG Hosted Monitor for all other operating systems. What’s more: our native PRTG Desktop application runs on Windows or macOS – for even quicker access & multi-server views.
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Bandwidth, servers, virtual environments, websites, VoIP services – PRTG keeps an eye on your entire network.
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