(The author works in a research institute. The LAN backbone network of our institute is built with ATM technology. The core switch is Fore7110 and has routing function. Through the Ethernet emulation of ELAN technology, 3 Fore7105 are connected to the bottom to form the ATM backbone network of the research institute, and the enterprise ATM network is connected to the top. . The network topology is a star tree structure. have)