L2 or L3 between access and distribution/core layers

Hi All,

Due to rapid growth and limited budget, our LAN currently spans 3 floors in our building as a single /21 subnet. We are about to gain an additional 2 floors so I now have an opportunity to get this under control, but I need a little help.

Each floor has an IDF supplying aprox 300 ports. Each IDF is about to get a new stack of L3 switches (8x Netgear M4300-52G-PoE+). I will run each floors LAN as it's own L2 network terminating on the switch stack and routing to a core/distribution layer.

We are small enough that we could use static routing, but the switches do support OSPF so i'd like to use that.

Looking a several design guides, there appear to be two methods for connecting the access layer to the core/distribution layer:

• Layer 2 - Each switch stack participates in a single OSPF area (broadcast)
• Layer 3 - Point-to-point links between the core and each access switch stack

Layer 2 Option This seems like the easier option.

• All uplinks from the access layer belong to the VLAN on the core and all participate in OSPF
• Each switch has a full view of the network

Layer 3 Option This seems a little more complex

• each switch stack only needs to get a default route from the core * failures are more rapidly detected

Is there anything I have missed/mis-understood or should know before building this new network?

EDIT: Diagrams