The performance of ATM switches are mainly influenced by switching fabric and scheduling algorithms. Input buffered switches have the strong advantage of efficient crossbar usage. This paper presents an input-queued crossbar switches fabric supporting high speed switching, analyzes the scheduling algorithms for unicast trafficts and multicast traffic based on virtualoutput queueing (VOQ).Focusing on their performance issues, some typical schedulers are compared. The performance of ATM switches are mainly influenced by switching fabric and scheduling algorithms. This paper presents an input-queued crossbar switches supporting supporting high speed switching, analyzes the scheduling algorithms for unicast trafficts and multicast traffic based on virtual output queueing (VOQ). Focus on their performance issues, some typical schedulers are compared.