Muftasoft TM

Inter-VLAN routing and explore how to configure subinterfaces on router interfaces. This is a crucial topic for network administrators, especially when dealing with segmented LANs. 🌐🔌

### What is Inter-VLAN Routing? - Inter-VLAN routing allows us to logically segment a Local Area Network (LAN) into different broadcast domains using Virtual Local Area Networks (VLANs). - Each VLAN acts as a separate broadcast domain, enhancing security, simplicity, and flexibility. - However, for communication between VLANs, we need a routing device (usually a router or Layer 3 switch).

### Methods of Inter-VLAN Routing: 1. Traditional Inter-VLAN Routing:

1. In this method, we use a router with multiple physical interfaces.
2. Each interface connects to a switch, with one interface per VLAN.
3. The switch ports connected to the router are set to access mode.
4. Each router interface becomes the default gateway for hosts in its associated VLAN.
5. When hosts from different VLANs need to communicate, traffic is routed through the router.
6. 
7. Example: If Host A (VLAN 10) wants to send a message to Host B (VLAN 20):

1. Host A checks if the destination IP is in its VLAN.

      2. If not, it forwards the traffic to its default gateway (router interface Fa0/0).
      3. Host A sends an ARP request to the switch to find the router's MAC address.
      4. The frame is unicast to the router, which then routes it to VLAN 20.
  - Each router interface handles traffic for its connected VLANs.

2. Router-on-a-Stick Inter-VLAN Routing:

1. In this approach, we use a single router interface (usually a subinterface).
2. The router interface connects to a trunk port on a switch.
3. The trunk carries traffic for multiple VLANs.
4. The router processes VLAN-tagged frames and routes between VLANs.
5. 
6. Example: Configure a subinterface on the router (e.g., ge-0/0.10 for VLAN 10 and ge-0/0.20 for VLAN 20).
7. The router's IP addresses on these subinterfaces serve as default gateways for hosts in their respective VLANs.

3. Multilayer Switch Inter-VLAN Routing:

1. Multilayer switches (Layer 3 switches) can perform inter-VLAN routing.
2. They have VLAN interfaces and routing capabilities.
3. Each VLAN has an associated SVI (Switch Virtual Interface).
4. The switch routes traffic between VLANs internally.
5. 
6. Example: Configure SVIs for VLAN 10 and VLAN 20 on the multilayer switch.
7. The switch handles inter-VLAN routing without an external router.

### Configuration Steps: 1. Traditional Inter-VLAN Routing:

1. Connect router interfaces to switch ports (access mode).
2. Assign IP addresses to router interfaces.
3. Set each router interface as the default gateway for its VLAN.

2. Router-on-a-Stick Inter-VLAN Routing:

1. Configure subinterfaces on the router.
2. Assign IP addresses to subinterfaces.
3. Set the router's IP addresses as default gateways for VLANs.

3. Multilayer Switch Inter-VLAN Routing:

1. Configure SVIs on the multilayer switch.
2. Assign IP addresses to SVIs.
3. Enable routing on the switch.

Remember, the choice of method depends on your network design and requirements. Happy routing! 🌐🚀