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ccna without work experience.Forwarding StatusFinally, after the forwarding delay timer expires, a port in the learning state will enter the forwarding state. In the forwarding state, the port will process BPDUs, update the MAC address table based on the frames received, and forward user traffic.Disabled State The disabled state is a special port state in which a port does not participate in STP. this may be due to the port being manually shut down by an administrator, manually removed from STP, disabled due to a security violation, or not functioning properly due to no physical layer signal (such as a patch panel cable being unplugged). Exam Essentials There are four main port states used by STP (802.1d): blocking (lasts 20 seconds), listening (lasts 15 seconds), learning (lasts 15 seconds), and forwarding, so the STP convergence time is 30.50 seconds. If a new root switch is discovered or if the network topology changes (a new switch is added or the state of a switch port changes), STP must be recalculated. In the blocking and listening states, only BPDUs are processed; in the learning state, MAC tables are created; in the forwarding state, user frames are transmitted between ports.STP keeps some ports in the blocking state to eliminate loops.13.2.6 Layer 2 ConvergenceAs described in the previous section, STP goes through a process consisting of multiple stages, which reduces the speed of convergence. For a switch, STP is in a converged state when it completes: the root switch is elected, the root port and the designated port are selected, the root port and the designated port are in the forwarding state and all other ports are in the blocking state.If the port must go through all 4 phases, the convergence time will be 50 seconds: the blocking state lasts 20 seconds, the listening state lasts 15 seconds, and the learning state lasts 15 seconds. If the port does not have to go through the blocking state and starts directly from the listening state, the convergence time will be only 30 seconds. This is usually the case when the root port is still valid and there are just other topology changes. Don't forget that no user traffic will be forwarded through the port until it enters the forwarding state. Therefore, if an STP recalculation occurs during the user's Telnet session, the connection will appear to the user as if it has stopped or been disconnected, and the user will obviously perceive this disruption.Exam Essentials STP converges when all root ports and the designated port are in the forwarding state and all other ports are in the blocking state.PortFast Overview.The faster the convergence rate, the shorter the interruption time to the user. To increase the convergence speed, the values of the two timers can be reduced, but blindly modifying them may cause more problems. For ports connected to the user, the PortFast function can be used to increase the convergence speed. PortFast should be used only on ports that do not cause Layer 2 loops, such as ports connected to PCs, servers, or routers, which are sometimes referred to as user ports or edge ports.PortFast-enabled ports are always in the forwarding state, even when STP is running and the root port and the designated port are going through various states. Thus PortFast ports on the same switch can still communicate with each other while STP is running, which reduces STP-induced outages to some extent. However, to communicate with other switch-connected devices, you must wait for STP to end and for the root and designated ports to enter the forwarding state.