the BPDUs it sends. Every bridge has a bridge ID. The bridge ID is a combination of the bridge priority and the bridge's MAC address. The bridge priority is a configurable two-byte field with a default value of 32,768. The lower the bridge ID value is, the more likely it is that the bridge will become the root bridge (the bridge with the lowest bridge ID becomes the root bridge). Chapter 8: Spanning Tree The root ID is similarly composed of two fields: the root priority and the root MAC address. The root priority is also configured with a value of 32768 (0x8000) by default. Should there be a tie between root priorities, the lower root MAC address is used to break the tie. Determine the best path to the root bridge If BPDUs from the root bridge are received on more than one port, there is more than one path to the root bridge. The best path is considered to be via the port on which the BPDU with the lowest path cost was received. Path costs are determined by adding each bridge's port priority to the initial path cost as BPDUs are forwarded from bridge to bridge. Determine the root port on each bridge The root port is the port on the switch that has the shortest path to the root bridge. 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 designated 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