ccna without it background

ccna without it background.. During a root switch election (such as when starting all switches in the network) ;. The switch receives a BPDU on the port that indicates that there is a path to the root switch that is more than what is currently used to get to the root switchthe paths are better.. The port is neither the root port nor the specified port.After a port enters the blocking state, it will remain in this state for 20 seconds by default (maximum expiration timer). In this state, the port only listensand processes BPDUs, and any other frames received on a port in the blocking state are discarded. In the blocking state, the switch tries to determine which port will be the root port, which port will be the designated port, and which port will remain blocked to eliminate all loops.Listening stateAfter the 20-second timer expires, the root and designated ports will switch to the listening state, while all other ports will remain in the blocking state. In the listening state, the port will continue to listen for BPDUs and examine the Layer 2 topology. Again, in this state, the port will only process BPDUs, and all other traffic will be discarded. The amount of time the port remains in this state is specified by the forwarding delay timer, which defaults to 15 seconds.Learning StateAfter the listening state ends, the root port and the specified port will enter the learning state. In the learning state, the port will also continue to listen and process BPDUs, but unlike the listening state, the port will begin processing user frames. When processing user frames, the switch checks the source address of the frame and updates its MAC address (port address) table, but does not forward the frames out of the port bound for the destination. The amount of time a port remains in this state is specified by the forwarding delay timer, which defaults to 15 seconds.