Chapter 4

Implementing Operation Quality

4.1. The architectural framework

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.

4.2. Implementation of resource management

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 ...

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