问题：

[多选] Which two design concerns must be addressed when designing a multicast implementation?（）

A . only the low-order 23 bits of the MAC address are used to map IP addresses
B . only the low-order 24 bits of the MAC address are used to map IP addresses
C . only the high-order 23 bits of the MAC address are used to map IP addresses
D . only the low-order 23 bits of the IP address are used to map MAC addresses
E . the 0x01004f MAC address prefix is used for mapping IP addresses to MAC addresses
F . the 0x01005e MAC address prefix is used for mapping IP addresses to MAC addresse