200 301 ccna

200 301 ccna.Step 1 First Bob sends the frame to SW3 ,Step 2 Because SW3's Gi(tapped interface is blocking, SW3 will then only forward the frame to SW1, but not to SW2 via GiO/2,Step 3 SW1 floods the frame through FaO/11 and GiO/1 interfaces, and SW2 floods the frame through FaO/11 and GiO/1 interfaces.Step 4 SW2 floods the frame through FaO/12 and GiO/1 interfaces.Step 5 SW3 receives the frame, but it ignores the frame forwarded from SW2 to SW3's GiO/2 interface because that interface is blocking.In the STP topology shown in Figure 1-4, the link between SW2 and SW3 is not used to communicate in the VLAN, which is a lesser negative effect from STP. Nevertheless, if the other two links fail, then STP converges immediately, transforming SW3's GiO/2 interface into a forwarding state and making it available for forwarding data. Tip: STP convergence (STPconvergence) is the process by which multiple switches jointly detect some change in the LAN topology and the switch changes the corresponding port to the blocking or forwarding state.At this point, the functionality of STP has been covered, and each port is placed in one of two states: forwarding or blocking. The more interesting question, and one that requires more thought to understand, is how and why STP makes this choice: How does STP control whether each interface is set to the blocking or forwarding state, and how does STP take advantage of redundant links to change the blocking or forwarding state of an interface for convergence in response to a network outage? The next section will answer each of these questions.3. How Spanning Tree WorksThe STP algorithm creates a spanning tree of interfaces that can forward frames. The tree-forwarding interface structure creates a single path to and from each Ethernet link, just as in reality a separate path can be traced along the root of the tree all the way to each leaf. Tip: STP predates the advent of LAN switches. Today, switches use STP, playing the same role as bridges.Today, switches use STP, playing the same role as bridges. However, many STP terms still refer to bridges. Given the goals of this chapter and STP, consider bridge and switch to mean the same thing.