Cisco (Cisco) switches? C3750-e? 4. Partitioning VLANs

"Introduction" Within a switched network, it is possible to segment and organize flexibly through VLANs. VLANs can group devices in a LAN. A group of devices in a VLAN communicates as if it were connected to the same line. VLANs are based on logical connections, not physical connections.

Types of VLANs

There are many different types of VLANs used in modern networks. Some VLAN types are defined by traffic category. Some other VLAN types are defined by specific features.

Data VLAN: used to deliver user-generated traffic. Also known as the "User VLAN," The Data VLAN is used to divide the network into user groups or device groups.

default VLAN: after the switch loads the default configuration for initial startup, all switch ports default to a portion of the VLAN. Any device connected to any port on the switch can communicate with other devices connected to other switch ports. The default VLAN for Cisco switches is VLAN1.

Eigen VLAN: The Eigen VLAN is assigned to the 802.1Q Trunk port. Trunk ports are links between switches that support the transport of traffic associated with multiple VLANs.

View VLANs

Enter the command in privileged mode show VLAN brief can view the current VLAN status.

You can see that all interfaces are under the default VLAN1.

Creating VLANs

When configuring a normal-range VLAN, the configuration details are stored in the switch flash memory named Vlan.dat file, the flash memory is permanent, and you do not need to use the copy running-config startup-config command. However, because other details are often configured on the Cisco switch while creating VLANs, it is preferable to save the run configuration changes to the boot configuration.

In global configuration mode, add a new VLAN with the VLAN command and name it.

In addition to entering a single VLAN ID, you can also use the VLAN command to enter a comma-delimited list of VLAN IDs or a range of VLAN IDs separated by hyphens.

assigning ports to VLANs

After the VLAN is created, the next step is to assign a port to the VLAN, and the access port can only be assigned to one VLAN at a time.

The purpose of the switchport mode Access command here is to set the port to access mode, which is optional, but it is strongly recommended that it be useful to ensure a secure best practice.

Use the interface Range command to join multiple interfaces to the specified VLAN at the same time.

Using the show interface Brief command again to view the VLAN status, you can see that the addition of the default VLAN shared three VLANs has an interface member. After testing, the ports between the VLANs are not able to exchange visits.

changing VLAN Port members

As you can see when assigning a port, you can assign the specified interface directly to another VLAN, which is not available in the original VLAN. Of course, you can also use the no switchport access VLAN command to unassign a specified interface from the specified VLAN.

This example removes interface 24 from VLAN 100.

Once again, using the show interface Brief command to view the VLAN status, you can see that the original gi3/0/24 under VLAN100 is back to the default VLAN 1.

Delete VLAN

Use the no VLAN command in global configuration mode to remove the VLAN specified in the switch.

Here we use the command to remove VLAN 100.

Using the show interface Brief command again to see the VLAN condition, you can see that the VLAN100 is gone, and there are several interfaces under VLAN 100, and there is no return to the default VLAN 1.

Alternatively, you can delete the entire Vlan.dat file by using the delete flash:vlan.dat privileged EXEC command. Once this command is executed and the switch is reloaded, the previously configured VLAN is no longer displayed. This method can effectively restore the VLAN configuration of the switch to the factory default state.

Verifying VLAN information

Once the VLAN is configured, you can use the show VLAN command to verify the VLAN configuration.

You can display VLAN information for the specified ID or name.

The show VLAN summary command shows the total number of VLANs configured.

Cisco (Cisco) switches? C3750-e? 4. Partitioning VLANs