VLAN Switch Port Modes

When you configure a VLAN, you must assign it a number ID, and you can optionally give it a name. The purpose of VLAN implementations is to associate ports with particular VLANs. You configure the port to forward a frame to a specific VLAN. As mentioned previously – Types of VLAN - you can configure a VLAN in voice mode to support voice and data traffic coming from a Cisco IP phone. You can configure a port to belong to a VLAN by assigning a membership mode that specifies the kind of traffic the port carries and the VLANs to which it can belong. A port can be configured to support these VLAN types:

 

 

 

 

 

Static VLAN 

 

This is when Ports on a switch are manually assigned to a VLAN. Static VLANs are configured using the Cisco CLI. This can also be accomplished with GUI management applications, such as the Cisco Network Assistant. However, a convenient feature of the CLI is that if you assign an interface to a VLAN that does not exist, the new VLAN is created for you.

Static Port mode configuration

Switch#config t

Switch(config)#interface fastEthernet0/15

Switch(config-if)#switchport mode access

Switch(config-if)#switchport access vlan 10

Switch(config-if)#end

 

Dynamic VLAN

 

 A dynamic port VLAN membership is configured using a special server called a VLAN Membership Policy Server (VMPS). With the VMPS, you assign switch ports to VLANs dynamically, based on the source MAC address of the device connected to the port. The benefit comes when you move a host from a port on one switch in the network to a port on another switch in the network; the switch dynamically assigns the new port to the proper VLAN for that host.

Voice VLAN 

 

 A port is configured to be in voice mode so that it can support an IP phone attached to it . Before you configure a voice VLAN on the port, you need to first configure a VLAN for voice and a VLAN for data.

Voice mode Configuration

Switch#config t

Switch(config)#interface fastEthernet 0/15

Switch(config-if)#mls qos trust cos

Switch(config-if)#switchport voice vlan 99

Switch(config-if)#switchport mode access

Switch(config-if)#switchport access vlan 10

Switch(config-if)#end

 

The configuration command mls qos trust cos ensures that voice traffic is identified and given priority traffic. Remember that the entire network must be set up to prioritize voice traffic. You cannot just configure the port with this command.

The switchport voice vlan 99 commands identifies VLAN 99 as the voice VLAN.

You can verify this by using the following command:

Switch1#show interfaces fa0/15 switchport

 

Name:   Fa0/15

Switchport:   Enabled

Administrative Mode:   static access

Operational Mode: down

Administrative Trunking Encapsulation:   dot1q

Negotiation of Trunking:   off

Access mode VLAN:   10 (VLAN0010)

Trunking Native Mode VLAN:   1(default)

Administrative Native VLAN tagging:   enabled

Voice VLAN:   99  (VLAN099)

The switchport access vlan 10 command configures VLAN 10 as the access mode (data) VLAN. You can see this verified in the bottom screen capture: Access Mode VLAN: 10 (VLAN0010).

 

 

 

 

 

Inter-VLAN Routing

 

Types of VLAN

 

VLAN Trunking

 

How a Root Port is selected on a Switch

How a Switch forward Frames

How a Root Bridge and Ports is selected on a Switch

VLAN Switchport Membership mode

VLAN Configuration on a Switch