Native VLAN

Native VLAN is generally a dot 1Q conception elaborated for backward compatibility with devices that don’t endorse VLANs. Frames that are derived from the native VLAN are not tagged when transferred out on the trunk links. Frames entered untagged on the trunk links are set to the native VLAN. VLANs can be as multitudinous as there are.1 Q trunks on the switch.

Why Native VLAN?

The Native VLAN is one conception defined in the 802.1 q grade that was created for backward compatibility with the old device that does not endorse VLANs. The concept at the back of the local VLAN is that a few network traffic still flows over the entire switched network even if the trunk fails.

Refer to this article to learn more on Native VLAN.

Advantages of Native VLAN:

• The excellent activity is to configure the local VLAN ID to VLAN 666 and to make assured that this VLAN is not applied everywhere with inside the network
•  Any of the ports should not be assigned to the native VLAN.

Example:

Native VLAN configuration
switch(config)#vlan999
switch(config)#end
switch(config)#int Gig1/0/1
switch(config-if)#switchport mode trunk
switch(config-if)#switchport trunk native vlan 999

Step 1: Create a network topology of these devices given below:

S.NO	device	Model-Name
1.	switch	3650-24PS
2.	pc	pc

Step 2: Configure Multilayer switch0 for native VLAN.

CLI commands for switch0:

Switch>en
Switch#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
Switch(config)#int Gig1/0/1
Switch(config-if)#switchport trunk encapsulation dot1q
 Switch(config-if)#switchport mode trunk
Switch(config-if)#
Switch>
Switch>en
Switch#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
Switch(config)#vlan 999
Switch(config-vlan)#exit
Switch(config)#int Gig1/0/1
Switch(config-if)#sw
Switch(config-if)#switchport trunk native vlan 999

CLI commands for switch1:

Switch>en
Switch#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
Switch(config)#int Gig1/0/1
Switch(config-if)#
Switch(config-if)#switchport trunk encapsulation dot1q d
%LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/1, changed state to down
%LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/1, changed state to up

Switch(config-if)#switchport mode trunk
Switch(config-if)#end
Switch#
Switch#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
Switch(config)#int Gig1/0/1
Switch(config-if)#switchport trunk native vlan 999
Switch(config-if)#end

Step 3: Now we will check the native VLAN interface trunk information:

• Command: show interface trunk
• As we can see native is set to 999 and encapsulation is 809.1q

Similarly with switch1:

• Command: show interface trunk
• As we can see native is set to 999 and encapsulation is 809.1q

Step 4: Now we will check for spanning-tree interfaces.

Step 5: Verifying the connection:

• To verify the connection we’ll ping the IP address of PC1 in PC0.
• Using ping command.
• In the below image as we can see we are getting replies from PC1 which means the connection is verified.