• 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)

SVIs

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