Hi,
The question now is, if I want to connect an end device to SW1 (say interface 20) how do I get traffic from the end device routed through SW1 to the other areas all the way to an end device connected to SW2.
Must I add the interface the device is connected to, to a VLAN? Can traffic be routed directly without adding the end device's interface to a VLAN and if so how ?
So, you can do it 2 ways, one is to add the end device to a vlan, create an SVI for that vlan and than add the SVI to the OSPF and the 2nd way, you can simply connect the end device to say port 20 and make that port a routed port (not switchport) and than give the PC one IP and the switch interface one IP and than add that interface to OSPF.
In the switching/LAN environment the first option in common because you can add multiple devices to the same vlan vs the second method is point-to-point,meaning you can only have 2 devices on that segment (switch and end device).
Also, usually, the first method using a vlan uses a bigger subset like /25 or 24 and the second method you just need two IPs, so usually a /30 is sufficient.
HTH
