200-301 cisco certified network associate

200-301 cisco certified network associate.. vlan x exists on that switch but is disabled (shutdown). Next is troubleshooting step 4b, whose primary function is to remind you to make sure that each switch has defined and not been disabled for that VLAN.The switch is usually informed of existing VLANs by using VTP or direct configuration on the local switch. for the purposes of the overhead book, it is assumed that VTP is disabled or set to use transparent mode. So, to support a particular VLANx, all switches must be configured directly using the vlan x command.These two issues can easily be seen with the output of the show vlan or show vlanbrief command. If the VLAN is not present on that switch, then these commands will not list the VLAN at all. in this example, using the vlan vlan-id configuration command will add this VLAN to the configuration. If the result list shows the VLAN, then its status is displayed together: active and act/lshut. the second status value indicates that the VLAN has been shut down. You can use the no shutdown vlan vlan-id global configuration command to resolve this issue. (3) Determine the trunk and the VLANs that are forwarded on the trunkCorresponding to step 4c, problems can be divided into two categories when starting to isolate them: those related to the working details of the trunk that is running, and those caused by an interface that should have been a trunk because it did not become a trunk.The first category of problems can be easily resolved by using the show interfacestrunk command, which lists information about all currently running trunks. Its most useful content is located in the last part of the output display, where the VLANs that will be forwarding traffic over the trunk are listed.0 In the output of this command, all VLANs displayed in this final list of VLANs need to meet the following criteria.The VLAN exists on the local switch and is active (refer to previous sections and the showvlan command).The VLAN has not been removed from the list of allowed VLANs for this trunk (configurable with the switchport trunk allowed vlan interface subcommand).This VLAN is not VTP-pruned on the trunk (this is a VTP feature and it will not be described in this section. (The reason it is listed is that it is mentioned in the show command output).The trunk in that VLAN is in the STP forwarding state (see the showspanning-tree vlan vlan-id command). Example 3-6 shows the output of executing the show interfacestrunk command, paying particular attention to the command output shaded to identify theThe last paragraph. In this example, trunking can only forward traffic in VLAN1 and VLAN4. Example 3-6 List of Allowed VLANs and Active Status VLAN List 66 Chapter 3 Troubleshooting LAN Switching