Inter-VLAN routing is essential for enabling communication between different VLANs within a network. Let's explore the three common methods of implementing inter-VLAN routing:

1. **Traditional Inter-VLAN Routing**:
   - In this method, a router with multiple physical interfaces is used.
   - Each interface on the router is connected to a switch, with one interface per VLAN.
   - The switch ports connected to the router are typically in access mode.
   - Each router interface becomes the default gateway address for hosts in its associated VLAN.
   - When hosts from different VLANs need to communicate, traffic is routed through the router.
   - This approach involves physical interfaces and is suitable for smaller networks.

2. **Router-on-a-Stick Inter-VLAN Routing**:
   - Also known as "subinterface" routing, this method uses a single router interface.
   - The router interface is configured with subinterfaces, each associated with a specific VLAN.
   - The subinterfaces are virtual interfaces that allow the router to handle traffic from multiple VLANs.
   - A trunk link connects the router interface to a switch, carrying traffic for all VLANs.
   - The router performs inter-VLAN routing based on the VLAN tags in the frames.
   - This approach is efficient for larger networks and reduces the need for multiple physical interfaces.

3. **Multilayer Switch Inter-VLAN Routing**:
   - Multilayer switches (Layer 3 switches) combine switching and routing capabilities.
   - They have VLAN interfaces (SVIs) for each VLAN, acting as virtual router interfaces.
   - SVIs allow the switch to route traffic between VLANs without an external router.
   - The switch maintains a routing table and performs inter-VLAN routing in hardware.
   - This method is efficient, especially in large networks, as it avoids bottlenecks caused by a single router.

Now, let's configure a basic example using a **multilayer switch**:

1. **Enable Routing Capability**:
   - On the switch, ensure that IP routing is enabled:
     ```
     Switch(config)# ip routing
     ```

2. **Create VLANs**:
   - Define the VLANs that need to be routed (e.g., VLAN 10, VLAN 20, and VLAN 30).

3. **Assign IP Addresses to VLAN Interfaces**:
   - Configure IP addresses for the VLAN interfaces (SVIs):
     ```
     Switch(config)# interface vlan10
     Switch(config-if)# ip address 192.168.10.1 255.255.255.0
     Switch(config-if)# no shutdown
     Switch(config-if)# exit

     Switch(config)# interface vlan20
     Switch(config-if)# ip address 192.168.20.1 255.255.255.0
     Switch(config-if)# no shutdown
     Switch(config-if)# exit

     Switch(config)# interface vlan30
     Switch(config-if)# ip address 192.168.30.1 255.255.255.0
     Switch(config-if)# no shutdown
     Switch(config-if)# exit
     ```

4. **Configure Hosts**:
   - Set the default gateway for hosts in each VLAN to the corresponding SVI IP address (e.g., 192.168.10.1 for VLAN 10).

Remember that inter-VLAN routing enhances network flexibility and security, allowing efficient communication across VLANs. Feel free to explore more advanced configurations based on your network requirements! 🌐🔗