Explanation: 1. BPDUs received are forwarded to the system module. 2. Frames received from the attached segment are processed. 3. Switched frames received from other ports are advanced. 4. The port in the forwarding state responds to network management messages. https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5000/sw/layer2/503_n1_1 /Cisco_n5k_layer2_config_gd_rel_503_N1_1_chapter9.html