The operational quality of the architectural framework of a network is based on a set of quality of service (QoS) modules organized into three planes:
– the control plane contains the mechanisms that enable the definition of paths along which user data are transferred. These mechanisms include admission control, QoS-based routing, and resource reservation. Such mechanisms also allow traffic restoration when faults affecting a network node or a link arise;
– the user plane contains mechanisms pertaining directly to user traffic. These mechanisms include classification and marking, shaping and policing, congestion avoidance and queuing;
– the management plane encompasses network operation, administration, and management mechanisms. These mechanisms also include traffic measurement and policy-based control.
A QoS module may be specific to a network node, e.g. for memory management, or applicable to a network domain, e.g. for QoS-based routing. Signaling between network nodes is imperative, particularly in the latter case, and can take place in any one these three logical planes.
The Internet Protocol (IP), Multi-Protocol Label Switching (MPLS) and Ethernet protocols provide, by default, a service without QoS (best effort), which partly explains their ease of implementation. The parameters of operation quality are not guaranteed. No network admission control device allows ...