This glossary contains explanations for commonly used terms in network measurement, and their acronyms, abbreviations, and aliases.



Application Programming Interface

An interface in software, which allows a third party to interact with the software programmatically.

API is analogous to a user interface: Whereas a UI offers software-human interaction, an API offers software-software interaction.


> DL, Received

Downlink / Received Direction

Refers to a network path direction where traffic is flowing from a remote point towards the observer.


Deep Packet Inspection

A method of processing packets, where the packet content is studied further than just the outermost transport layer.

DPI does not necessarily imply that the actual payload of the packet is inspected.



Global Navigation Satellite System

A general term under which all the different global satellite navigation systems (e.g., GPS, GLONASS, Galileo, BDS) fall.


Generic QoS Measure Algorithm

A parameter based QoS mapping algorithm allowing to map a single quality indicator from several parameters. When tuned with real user tests, GQoSM allows also QoE estimations.

GQoSM, however, is meant for evaluating the influence of the network to the quality – not for estimating the absolute quality (e.g., including the defects of codecs, etc.). For more information, see our article on Quality of Experience.


Graphical User Interface

User interface which features graphical elements, such as windows, buttons, dialogs, images, and controls.


> IP

Internet Protocol

The standard protocol in computer networks for addressing and transferring packets.

Wikipedia article on Internet Protocol



Local Area Network

A closed network or a segment of network comprising a single address space.



Mean Opinion Score

The most widely used measure for QoE.


Multiprotocol Label Switching

A routing technique in telecommunications networks that forwards data based on short path labels rather than long network addresses.



Network Address Translation

A technique for remapping an IP address space

Wikipedia article on Network Address Translation


Network Interface Card

A piece of hardware which offers a device a networking interface.


Network Time Protocol

A very common protocol for synchronizing the clocks of devices across a network.


> OS

Operating System

A software which manages the resources of a device and provides a confined space for users for managing the device and for running software.

Example operating systems: Windows, Ubuntu, Android, MacOS.


> Packet Loss Timer

Packet Loss Timer

Qosium determines packet losses by waiting each packet a predefined amount of time. Packet loss timer defines this duration.

If this value is set too small, packets exceeding this duration in the traversal of the measurement path will be incorrectly considered lost. A large value yields more precise results, but causes a lag to the reporting of lost packets, since Qosium needs to wait for this duration for packets before reporting them as lost.

Loss timer should be always at least 2 × control packet interval. The latter parameter is typically set automatically according to the averaging interval, but it can be also changed manually. In order to have short packet loss timer value, set the control packet interval as well.

> Promiscuous Mode

Promiscuous Mode

A mode in network interfaces, which allows packet sniffers to process packets even if they are not designated to said network interface.

This mode is essential in Qosium, since it’s fairly common to measure network traffic by placing Probes somewhere in-path or off-path via port mirroring instead of end-points.

Some network interfaces do not support promiscuous mode, so try turning it off if starting measurement results in an error, or no packets are captured.

For more information, see the Wikipedia article on Promiscuous mode.


Pseudo-Subjective Quality Assessment

A neural network based model for estimating QoE.

For more information, see our article on Quality of Experience.


Precision Time Protocol

A protocol for synchronizing the clocks of devices across a network. The reached synchronization accuracy is typically considerably better than with NTP.



QoS Measurement Control Protocol

Kaitotek's proprietary protocol for controlling measurements and gathering measurement results.

QMCP is a protocol made by Kaitotek to optimize QoS measurement control communications. TCP is used in the transport layer (currently), but QMCP controls its sessions. All Qosium products use QMCP.

> QoE

Quality of Experience

Indicates the overall performance of a network application, and how user's experience is affected by the network conditions.

For more information, see our article on Quality of Experience.

> QoS

Quality of Service

Indicates the overall performance of the network and its ability to serve applications.

For more information, see our article on Quality of Service.


> Robust QMCP Mode

Robust QMCP Mode

A feature which allows Qosium products to re-connect each other and carry on the measurement, even if connectivity is momentarily lost.

If robust QMCP mode is not enabled, the measurement is stopped if the connection between Qosium products is lost. It is recommended to keep this feature always on unless there’s a good reason to disable it.


Real-time Transport Protocol

A transport protocol for applications with real-time constraints, such as video streams, VoIP, and remote control.



Transport Control Protocol

A robust connection-oriented transport protocol for transferring non-realtime data reliably.



User Datagram Protocol

A simple, fast, unreliable transport protocol.

> UI

User Interface

User Interface is the segment of the software that provides a way for human-software interaction.

> UL, Sent

Uplink / Sent Direction

Refers to a network path direction where traffic is flowing away from the observer towards a remote point.



Virtual LAN

A LAN seqment which has no physical hardware, but instead is carried over network.

> VoIP

Voice over IP

Refers to technologies which enable a delivery of voice communication over IP network.


Virtual Private Network

A technique to provide a secure tunnel over a public network.



Wireless LAN

A LAN segment which operates wirelessly.