Quality of Service (QoS) is a term that is frequently used in relation to VoIP .
If the DSL line is working to capacity, speech packets of a telephone call only arrive at the telephone with delay or even not at all. Packaged in a router it guarantees bandwidths for certain services.
If, therefore, the line is working to capacity, QoS slows down the download speed as soon as a call arrives. In this way, the necessary bandwidth for the call is guaranteed.
Implementation in IP networks
QoS on Layer 3
On the theoretical level, QoS can be implemented by prioritizing or parameterizing data traffic, reserving data rates, limiting data rates and optimizing packets. Technically, there are two mechanisms for this:
- Either one registers pending data flows with all active network components (routers etc.) and reserves the required data rate (IntServ, Integrated Services),
- or you mark all data packets and the active network components treat/prefer the packets according to their markers (DiffServ, Differentiated Services).