• Layer 2 devices used for forwarding traffic between nodes in a LAN
  • Switch PDUs are called Frames; Ethernet encapsulation including a header and trailer. (Multilayer/Layer 3 Switches are an exception)

Multilayer Switches

A switch that also has some routing/layer 3 functionality. Notably, this allows it to internally route traffic between multiple VLANs without the assistance of a separate router.

Also called a Layer 3 switch

IP Routing

Allows a multilayer switch to route layer 3 traffic through appropriately configured interfaces like a router would.

  1. enable IP routing with ip routing in global configuration
  2. configure interfaces with no switchport to use as routed ports (only need this for trunk ports)


SVI = Switch Virtual Interface

Use these in a layer 3/multilayer switch to route multiple VLANs through a single trunk port

  1. Ensure that all necessary VLANs exist on the switch
    1. check with show vlan brief
    2. Create new VLAN(s) with vlan (vlan-number) if necessary
  2. select the first VLAN as an interface
    1. int (vlan-id)
  3. assign the VLAN an IP address, typically the last usable in the subnet:
    1. ip address (ip-address)
  4. repeat for all VLANs