The invention provides quality assured network services in a multi-domain network and comprises a network service management device for managing device clusters incorporated within the operations management network of each provider network and receiving service orders, and a multi-domain service broker for providing a broker function for achieving agreement between a plurality of providers, and the multi-domain service broker further comprises a device for collecting domain information and information relating to the services each provider is able to provide from the network service management devices, and a device which on receipt of a network service request from a customer, extracts the network service management device of the domain which is able to satisfy the required quality level, and then issues instructions for the setting of the required information within the extracted network service management device.