Please let me know if is scenario on picture possible. I don't know how to configure layer 3 switch over routed ports with trunk link which is connected to layer 2 switch.

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  • Could you please write configuration of L3 Switch here ? – Emir Pjanic Oct 18 '15 at 13:20

In your sheme you need 3 trunk links (if there is only one physical connection between these switches):

  • switch 1 to switch 0
  • switch 0 to switch 2
  • switch 2 to L3SW

The routing between these subnets will be handled by the L3 switch. so if pc 0 wants to ping to pc 1:

PC0 > (gets it on his vlan 1 port) switch 1 (trunk) > switch 0 (trunk) > switch 2 (trunk) > L3SW (vlan1 > vlan2) (sends it out of its trunk port) > switch 2 (trunk) > switch 0 (trunk) > switch 1 (vlan2) > pc1


A trunk link is a switched link, not a routed link. The port would not be a routed port, just an ordinary switch trunk link.

What you need to do is to create a layer-3 virtual port for each VLAN coming in on the switched trunk port. Cisco calls these virtual interfaces, SVIs. The SVIs are the routed ports, not the physical ports.

Based on your diagram, you seem to want to create a router-on-a-stick. You can do this. The port on the layer-3 switch will be configured as a normal switch trunk port. Inside the layer-3 switch, you create an SVI for each VLAN on the trunk, and you configure it as you would a routed port (IP address, etc.).

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