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About QoS

Normally the Internet works with the best-effort philosophy: each user shares bandwidth with others, thus his data transmission competes with the transmissions of the other users. The packaged data are sent the best possible way, according to the available routes and band. When there is a jam, the packages are discarded without distinctions. There is no guarantee that the service will be successfully performed. However, applications such as voice over IP and videoconference need such guarantees.

With the implantation of quality of service – QoS, it is possible to offer more guarantees and security to advanced applications, since the traffic of these applications has priority over traditional applications.

With the use of QoS the packages are marked so as to distinguish the kinds of services and the routers are configured to create distinct lines to each application, according to their priorities. Therefore, a range of bandwidth, inside the communication channel, is reserved so that, in case of jams, certain types of data flow or applications can have priority in terms of delivery.

There are two models of QoS implementation: integrated services (IntServ) and differentiated services (DiffServ). IntServ is based on the reservation of resources, while DiffServ is a proposal in which the packages are marked according to pre-determined classes of services.