When configuring normal range VLANs, the configuration details are stored in flash memory on the switch in a file called vlan.dat. Flash memory is persistent and does not require the copy running-config startup-config command. However, because other details are often configured on a Cisco switch at the same time that VLANs are created, it is good practice to save running configuration changes to the startup configuration.
Figure 1 displays the Cisco IOS command syntax used to add a VLAN to a switch and give it a name. Naming each VLAN is considered a best practice in switch configuration.
Figure 2 shows how the student VLAN (VLAN 20) is configured on switch S1. In the topology example, the student computer (PC1) has not been associated with a VLAN yet, but it does have an IP address of 172.17.20.22.
Use the Syntax Checker in Figure 3 to create a VLAN and use the show vlan brief command to display the contents of the vlan.dat file.
In addition to entering a single VLAN ID, a series of VLAN IDs can be entered separated by commas, or a range of VLAN IDs separated by hyphens using the vlan vlan-id command. For example, use the following command to create VLANs 100, 102, 105, 106, and 107:
S1(config)# vlan 100,102,105-107