200 301 ccna price

200 301 ccna price.As a result, SW3 considers SW1 to still be the optimal switch, while SW3 itself is not the root.Open.Next, SW3 re-estimates the selection of the root port. At this point, SW3 can only receive Hello messages on the GiO/2 interface. Thus GiO/2 will become SW3's new root port regardless of the root overhead (this overhead should be 8, provided that the STP overhead in Figure 1-7 and Figure 1-8 has not changed).Finally, SW3 re-estimates its own other interfaces as designated ports. In this example, there is actually no operation at all. Because no other switches are connected to SW3, SW3's interface FaO/13 is already the designated port and will continue to serve in that role. Changing the STP Interface StateSTP uses the concept of roles and states. Roles, such as root and designated ports, are related to the way STP analyzes the LAN topology. States, such as forwarding and blocking, tell the switch whether to send or receive frames. When STP converges, the switch selects new port roles that determine its state (forwarding or blocking).A switch can change directly from the forwarding state to the blocking state, but a transition period must occur to change from the blocking state to the forwarding state. For example, when a switch uses port G0/1 as its RP (role), this port is in the forwarding state. After convergence, G0/1 may be neither an RP nor a DP; the switch can immediately change the port to a blocking state.When a previously blocked port needs to be converted to the forwarding state, the switch first changes the port to the intermediate interface state of the two switches. These temporary states can help avoid the following temporary loopback phenomena.Listening:Similar to the blocking state, an interface in this state does not forward frames. During the listening state, the switch suspends the use of old (unused) MAC table entries and does not receive frames from these MAC addresses during this period. These MAC table entries are likely to be the root cause of the temporary loopback.Learning: interfaces in this state still do not forward frames, but the switch begins to learn MAC addresses from frames received on such interfaces. the STP transitions the interface from a blocking state to a listening state, then to a learning state, and finally to a forwarding state. the STP sets the interface1.2 Base Content 19