Topic 2: VLAN and InterVLAN Routing

• VLAN - is a custom network which is created from one or more local area networks. It enables a group of devices available in multiple networks to be combined into one logical network.
• VLANs in networking are identified by a number
• VLAN 0-4095 - is a VLAN range; reserved VLAN, which cannot be seen or used.
• VLAN 1 - This is a default VLAN of switches. You cannot delete or edit this VLAN, but it can be used
• VLAN 2-1001 - It is a normal VLAN range. You can create, edit, and delete it.
• VLAN 1002-1005 - These ranges are CISCO defaults for token rings and FDDI. You cannot delete this VLAN.
• VLAN 1006-4094 - It is an extended range of VLAN
• Inter-VLAN Routing - is a process for forwarding network traffic from one VLAN to another using a router
• Inter-VLAN Routing Methods:

  1. Legacy Inter-VLAN Routing
  2. Router-On-A-Stick
  3. Multilayer Switch Inter-VLAN Routing
• Legacy Inter-VLAN Routing - In this method, multiple router interfaces are used, each connecting to a switch port in different VLANs. These interfaces are served as default gateways, which requires additional cabling when the network has to be expanded.
• Router-On-A-Stick - In this method, one physical interface port is used for routing the traffic between the network segments. The network administrator doesn’t need to create separate VLAN interfaces like fa0/1 to fa0/10.
• Multilayer Switch Inter-VLAN Routing - can perform Layer 2 and Layer 3 functions. Routers are not required anymore.