VLAN lessons

  • Frames forwarded in the Native VLAN
    Trunk Native VLAN

    What is the Native VLAN?

    As you remember from the previous lesson, trunk ports send and receive Ethernet frames tagged with IEEE 802.1q VLAN tags.

  • MultiLayer Switch
    InterVLAN routing using Layer 3 switch
    Multilayer switches can forward frames based on MAC address information and can also forward IP packets based on IP destination. That is why they are also referred to as Layer 3 switches.
  • Router on a stick
    Router on a stick (ROAS)
    Router-on-a-stick (ROAS) is a technique to connect a router with a single physical interface to a switch and perform IP routing between VLANs. From the switch's perspective, this physical link is configured as a trunk port allowing all VLANs that are going to be routed. From the router's perspective, this physical interface is represented as multiple virtual sub-interfaces, one for each VLAN.
  • Forwarding Data Between VLANs

    Connectivity between VLANs

    LAN switches forward frames based on Layer 2 logic. This means that, when a switch receives an Ethernet frame, it looks at the destination MAC address and forwards the frame out another interface or multiple interfaces if it is a BUM frame.

  • VLAN Trunking

    Multiswitch broadcast domains

    In the previous lesson, we explained that when a broadcast frame is received on any switch port, the switch forwards it out to all its other ports.

  • VLAN Concept

    LAN switches and BUM traffic

    Before understanding the VLAN concept, you must first have an understanding of two core concepts about the Ethernet standard - what is a broadcast domain and what is BUM traffic. Let's start with the BUM data type.