200 301 exam cost

200 301 exam cost.The per-switch root overhead (which actually comes from STP port overhead as well) is used when the switch decides which switch port is to be the designated port (DP) for each LAN section.There is no doubt that the Cisco switch will allow you to configure the BID and STP port overhead section settings of the switch, which in turn will affect the choices made by each switch for STP.Per-VLAN Configuration Setting ItemsIn addition to supporting the configuration of BID and STP port overhead, Cisco switches have the ability to set the values of these two items specifically for each VLAN. By default, Cisco switches use IEEE 802.ID instead of RSTP (802.1w), a Cisco proprietary feature called Per-VLAN Spanning Tree Plus (PVST+). PVST+ (often simply abbreviated as PVST today) creates a different STP instance for each VLAN . Therefore, it is important to have a basic understanding of PVST+ before viewing the STP parameters that can be modified because each STP instance has a different value for the configuration settings.Administrators can use PVST+ as a tool to adjust the load balancing of STPs. By giving different values to the STP configuration parameters for a VLAN, the administrator is able to enable the switch to select different RPs and DPs in different VLANs. Thus, traffic in some VLANs can be forwarded to a trunk and traffic in other VLANs can be forwarded to different trunks.Figure 2-2 shows the basic concept, with SW3 forwarding odd-numbered VLAN traffic to the left trunk (GiO/1),and even-numbered VLANs tosent to the trunk on the right (GiO/2).Figure 2-2 Load Balancing in PVST+ In the next few pages, you will specifically discuss how the BID and STP port overhead for each VLAN can be modified when using the default PVST+ mode.Bridge ID and System ID ExtensionsOriginally, a switch's BID was formed by merging the switch's 2-byte priority with its 6-byte MAC address. Later, IEEE changed this rule to split the original priority field into two separate fields, a 4-bit priority and a 12-bit subfield called the System ID extension (representing the VLANID), as shown in Figure 2-3.