The MTD655 is a highly integrated, 10M/ 100M dual speed hub with build_in 2 port switch. Support 4 RMII ports and 1 MII port for 10M/ 100M operation, and meet 100M_hub class_2 spec when connect with external PHYceivers. The MTD655 provides two Inter-repeater stacking bus for 10M and 100M expansion each, easily stack to 4 units without any external arbitration logic. If using external arbitration logic and proper bus driver, can stack to 6 units and up. The build_in 2 port switch, support 2k MAC addresses filtering, and use low cost asynchronous high speed SRAM (128k*8) one pcs only for packet buffering. This 2 port switch can also be configured to be up_link switch when hub is under slave mode.