In recent years,Grid computing applications are becoming more and more important to the scientific and business communities and are likely to open to the consumer market and widely develop in the near future,which is a great challenge brought by the potentially large number of Grid users(perhaps millions)and high frequency of their job requests.Automatically switched optical network(ASON),which is a promising high capacity intelligent transport network infrastructure,has been already deployed in the world and regarded as a promising solution to foster the expansion of Grid computing from local area networks to wide area networks.However,by theoretical analysis and simulative evaluation of Grid job blocking in the distributed call and connection setup process of ASON,this paper verifies that ASON and the conventional admission control mechanism confront a problem in supporting future large-scale Grid computing.In order to address this issue,a novel dynamic call and connection admission control(DCCAC)scheme is proposed to improve the network performance and guarantee quality of service(QoS)of Grid applications.This scheme is applicable with complete network information,no network information and partial network information.Numerical results show that the DCCAC scheme can improve the efficiency of the network to a great extent.Moreover,all the analysis and algorithms in this paper are based on ITU-T ASON recommendations,which make the DCCAC scheme more applicable in network engineering for future Grid computing. In recent years, Grid computing applications are becoming more and more important to the scientific and business communities and are likely to open to the consumer market and widely develop in the near future, which is a great challenge brought by the potentially large number of Grid users (perhaps millions) and high frequency of their job requestss.sutomatically switched optical network (ASON), which is a promising high capacity intelligent transport network infrastructure, has been already deployed in the world and ideal as a promising solution to foster the expansion of Grid Hosted by local area networks to wide area networks. Hosted by theoretical analysis and simulative evaluation of Grid job blocking in the distributed call and connection setup process of ASON, this paper verifies that ASON and the conventional admission control mechanism confront a problem in supporting future large-scale Grid computing. order to address this issue, a novel dynamic call and connection admission control (DCCAC) scheme is proposed to improve the network performance and guarantee quality of service (QoS) of Grid applications. This scheme is applicable with complete network information, no network information and partial network information. Numerical results show that the DCCAC scheme can improve the efficiency of the network to a great extent. More the analysis and algorithms in this paper are based on ITU-T ASON recommendations, which make the DCCAC scheme more applicable in network engineering for future Grid computing.