200 301 ccna book

200 301 ccna book.The processing method used by STP, sometimes referred to as the Spanning Tree Algorithm (STA), selects the appropriate interface and sets it to the forwarding state. For interfaces that are not selected for the forwarding state, STA sets them to the blocking state. In other words, STP only selects the interfaces that need to be set to the forwarding state and sets the remaining interfaces to the blocking state.STP selects the interfaces to be set to the forwarding state based on the following 3 criteria.STP pushes a root switch and sets all interfaces that are working on the root switch to the forwarding state.Each non-root switch calculates a port that has the lowest management overhead between itself and the root switch, which is called the rootcost of the switch. STP sets the port to the forwarding state, and the port with the least-root-cost is called the root port (RP) of the switch.12 Chapter 1 Defining the Spanning Tree ProtocolMany switches will be connected to the same Ethernet network segment, and in modern networks, usually two switches are connected to each other. Comparing these switches connected to the same Ethernet link to each other allows you to select a switch with the lowest root overhead and set that switch to the forwarding state. These switches are called Designated Switches, and the switch interface connected to that segment is called a Designated Port (DP).Tip: The real reason that all working interfaces of the root switch are set to the forwarding state is that they all become Designated Ports (DPs). This makes it easier to remember that all working interfaces of the root switch will forward frames.All other interfaces are set to the blocking state. Table I. summarizes the reasons why STP sets ports to the forwarding or blocking state. Table 1-3 STP: Reasons for Forwarding and Blocking(iEnd ( Feature STP Status Description