In a router-on-a-stick configuration, it is important to Configure Native VLAN on Cisco Router to handle untagged traffic properly. The native VLAN is used to process incoming untagged packets on the router interface.
There are two ways to configure native vlan on a Cisco router: one is using the physical interface of the router, and the other is using the router’s sub-interfaces. Let’s explore them one-by-one.
Method 1: Configuring the Native VLAN on a Subinterface
The first method involves configuring the native VLAN on a subinterface of the router. Follow these steps:
1. Access the configuration mode of the router.
Router> enable
Router# configure terminal
2. Create a sub-interface for the desired VLAN, replacing <vlan_id> with the appropriate VLAN ID.
Router(config)# interface gigabitEthernet 0/0.<vlan_id>
3. Configure the encapsulation type and specify the native VLAN using the following command;
Router(config-subif)# encapsulation dot1q native
4. Assign an IP address to the subinterface within the network range of the corresponding VLAN.
Router(config-subif)# ip address <subnet_mask>
Method 2: Configuring the Native VLAN on the Physical Interface of router
The second method involves configuring the native VLAN directly on the physical interface of the router. Follow these steps:
1. Access the configuration mode of the router.
Router> enable
Router# configure terminal
2. Remove the sub-interface associated with the native VLAN, if present (You can use show ip interface brief to check for interface configuration).
Router(config)# no interface gigabitEthernet 0/0.<vlan_id>
3. Enter the configuration mode for the physical interface.
Router(config)# interface gigabitEthernet 0/0
4. Assign an IP address to the physical interface within the network range of the native VLAN.
Router(config-if)# ip address <subnet_mask>
By configuring the IP address directly on the physical interface, the native VLAN is implicitly set to the VLAN associated with the IP address.
Conclusion
With what we have covered so far, you have seen the two methods for configuring native VLAN on a Cisco router in a router-on-a stick configuration.
Method 1 involves configuring the native VLAN on a subinterface, while Method 2 configures the native VLAN directly on the physical interface. Both methods allow the router to properly handle untagged traffic within the native VLAN.
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