Grid computing is an emerging computing paradigm that will have a significant impact on the next generation information infrastructure. Networking systems form the foundation of Grid computing and must be integrated into the Grid. Service-oriented architecture is the basis of Grid computing; therefore service-oriented network description and discovery are the keys to network-Grid integration. High-performance Grid computing must select appropriate network services that meet the Quality of Service (QoS) requirements of various Grid applications. However, current Grid service description and discovery approaches are based on functional criteria instead of performance criteria thus are insufficient to support network service discovery. In this paper, a new description approach is proposed for describing QoS capabilities of network services. Based on this new description approach, a performance-based service discovery technology is developed for selecting network services that meet the QoS requirements of Grid applications. The network service description and discovery technologies developed in this paper are highly flexible and applicable to various networking systems crossing multiple heterogeneous domains. The network service discovery system proposed in this paper is embedded in the serviceoriented Grid architecture and can be implemented within the current Grid service discovery framework.