Layer 2 Switches

These are standard switches that are only able to operate on the Data Link Layer.

Management IP

Layer 2 switches don’t perform packet routing and don’t build a routing table. That creates a problem if we want to configure a Layer 2 switch using Telnet or SSH. Thankfully, there’s a workaround!

We can assign an IP address to a SVI to allow remote connections to the switch’s CLI. SVIs are more commonly used with Layer 3/Multilayer Switches, so read up on them below if you need to.

  • (config)#interface vlan1
  • (config-if)#ip address ip-address netmask
  • (config-if)#no shutdown
  • (config-if)#exit
    • Simply configure an IP address on the SVI as you would on a multilayer switch, and enable the interface if necessary.
  • (config)#ip default-gateway ip-address
    • Configure a default gateway. Depending on the configuration of VLANs, the switch may not be able to communicate with the device trying to configure it without one.

Layer 3/Multilayer Switches

Switches with some IP routing capability. You can sort of think of these as a router with many more interfaces, although they aren’t quite as graceful at IP routing as a dedicated router… You’ll see what I mean when you try configuring one.

The primary reason for multilayer switches is to route traffic between multiple VLANs within a network, without having to use a separate router in a Router-on-a-Stick configuration.

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