Quality of service (QoS) aspects in telecommunication networks interrelate requirements of users and applications with network architectures supporting relevant transmission properties. New challenges arise in multi service platforms with increasing variety of service demands, which comes together with a higher variability in traffic profiles. We try to give a general and comprehensive picture of the effect of traffic characteristics and control mechanisms on quality of service (QoS). Broadband access platforms are considered from source traffic profiles to QoS aware dimensioning for aggregated traffic in the IP backbone. Networks based on multiprotocol label switching (MPLS) are included, which combine capabilities for network monitoring, planning and traffic engineering with full support of differentiated and integrated services as main QoS concepts introduced by the Internet engineering task force (IETF).