Hello Steven
You are indeed correct, strictly speaking, you don’t need to enable routing on the access switches. The configuration of the default gateway should be enough for the ASW switches to achieve reachability to the rest of the network. However, the requirement stated in the lesson was:
Configure the campus network so all VLANs, point-to-point links, and loopback interfaces are reachable.
In order for this to occur, you must either configure default routes on all the devices or somehow advertise the 10.0.128.6 and 10.0.128.7 addresses to the rest of the topology.
Well, that’s not entirely true. Layer 3 shouldn’t be enabled for use by the end devices, yes, but the switch can use Layer 3 (i.e. routing) for the switch itself to achieve connectivity with other devices on the network for management and control plane purposes. The default gateway will suffice, but you can also use OSPF just for this purpose if you choose to. It’s a matter of design preference.
Hmm, that’s interesting. Thanks for sharing that, it’s good for others to keep this in mind to see if they get similar results.
I hope this has been helpful!
Laz