200 301 ccna cost

200 301 ccna cost.As shown in Figure 1-8, because the overhead from interface GiO/1 to the root switch (5) is less than the other interfaces (GiO/2 to the root has an overhead of 8) ,SW3 selects the GiO/1 interface as its RP. similarly, SW2 selects GiO/2 as its RP with an overhead of 4 (SW1 has an announcement overhead of 0 and SW2 has an overhead of 4 for the GiO/2 interface). Each switch sets the root port to the forwarding state.In more complex topologies, the selection of the root port is not as simple as this. The "STP Troubleshooting" section in Chapter 2 shows a more complex example, where the root port selection requires some thought.(SISelecting the Designated Port for Each LAN SegmentThe final step in the STP process is to decide on the STP topology, which is to select the Designated Port (DP) for each LAN segment. The designated port on each LAN segment, in turn, is the switch port that advertises the lowest overhead Hello message to a LAN segment. When a non-root switch forwards a Hello message, this non-root switch sets the overhead field of this Hello message to the overhead of that switch to the root. In effect, of all the switches connected to the same segment, the switch with the lowest overhead to the root becomes the DP on that segment.For example, in the preceding Figure 1-6, the bolded parts of the Hello messages for SW2 and SW3 determine how the DP on that segment is selected O Note the overhead to the root switch listed for SW2 and SW3, respectively (SW2 overhead is 4,SW3 overhead is 5).SW2 lists the lower overhead because16 Chapter 1 Defining the Spanning Tree ProtocolGiO/1 port of this SW2 becomes the designated port for this LAN segment. All DPs are set to the forwarding state, and in this example, the GiO/1 port of SW2 will be set to the forwarding state. If the announcements have the same overhead, the switch with the lower BID will be selected to break the deadlock. In this example, SW2 will win,because SW2s BID is 32769:0200.0002.0002, which is smaller than SW3's BID of 32769:0200.0003.0003oHint: Other judging criteria are needed in some cases, although they are rarely used at this time. If a hub is used, then a single switch can connect two or more interfaces to the same conflict domain. In this case. a switch listens for its own BPDUs. if the switch is equal to itself. two additional judging methods need to be used: lowest interface STP first and if still equal. the interface with the lowest internal interface number is selected. :