e. The root bridge does not have root ports; it only has designated ports. Determine the designated port on each segment The designated port is the port on the segment that has the shortest path to the root bridge. On segments that are directly connected to the root bridge, the root bridge's ports are the designated ports. Elect a designated bridge on each segment The bridge on a given segment with the designated port is considered the desig- nated bridge. The root bridge is the designated bridge for all directly connected segments. In the event that two bridges on a segment have root ports, the bridge with the lowest bridge ID becomes the designated bridge. Block nonforwarding ports Ports that have received BPDUs, and are neither designated nor root ports, are placed into a blocking state. These ports are administratively up, but are not allowed to forward traffic (though they still send and receive BPDUs). Always configure a switch to be the root bridge. Letting the switches configure themselves is dangerous because they will choose the switch with the lowest MAC address, which will usually be a switch other than the one it should be. As a general rule, you should not let net- working devices make critical decisions using default values. It will cause your network to behave in unexpected ways, and will cause you to fail higher-level certification exams, which are designed to catch you in exactly this way. Usually, the device that should be the root bridge will be obvious. The root bridge should generally be one of the core switches in your design. Preventing Loops with Spanning Tree Every port on a switch goes through a series of spanning tree states when it is brought online, as illustrated in the flowchart in Figure 8-5. These states transition in a pattern depending on the information learned from BPDUs received on the port. Disabled Initializing Blocking Listening Learning Forwarding Figure 8-5. Spanning tree port states These are the spanning tree states: Initializing A port in the initializing state has e