ATC-405 integrates a 5-port switches controller, SSRAM, and 5 10/100 Ethernet transceivers. Each of the transceivers compliers with the IEEE802.3, IEEE802.3u, and IEEE802.3x specifications. The DSP approach is utilized for designing transceivers with 0.16um technology; they have high noise immunity and robust performance. ATC-405 operates in store and forward mode. ATC-405 have a lot of rich feature for different application, include router application, firewall, IEEE 802.1Q, IGMP snooping, policy-based QoS. It provides powerful QoS function, include traffic policy, traffic meter, and flexible queue scheduling (WRR/WFQ/SP). In virtual LAN, ATC-405 support port-based VLAN and IEEE 802.1Q tag-tagged VLAN (up to 16 VLAN groups). ATC-405 support up to 2K MAC addresses. The address table can configure either “2K unicast addresses” or “1K unicast addresses and 1K multicast addresses“. The Multi-Field classification is powerful classifier (layer2 to layer 4 packet headers) in packet classification. The classifier divides incoming packets into multiple classes based on prescribed rules. Each traffic class from classifier can drop out-of-profile packets, monitor traffic, specify forwarding behavior, and specify output queue.