What is Layer 2 Mesh and what is the difference between Layer 2 and Layer 3?

The major difference between Layer 3 Mesh to Layer 2 is, Layer 3 Mesh AP acts as like a router yet Layer 2 Mesh AP acts as like a bridge.

That is in a Layer 3 Mesh AP network, each standalone Mesh AP will have two (relay mode) or three (gateway mode) IP Subnets. Take a Gateway Mesh AP as the example, it will have Local IP subnet, Backhaul IP subnet and the IP subnet for WAN/Internet. The Mesh AP will base on IP address to route the packets.

Then, for a Layer 2 Mesh AP, each node will act as like a 2-port or 3-port bridge or switch to forward the packets base on MAC address.

So, base on the view of network expansion, Layer 3 Mesh AP help to expand the IP network with just easily turn on the Mesh AP to bring you a new IP subnet. And the drawback is it requires more complicate installation / planning or routing knowledge. Also the packet routing will have some delay to the network performance.

And Layer 2 Mesh AP, just like an Ethernet Switch or hub, just turns it on and it will provide the Layer 2 network service for wireless user.

The following table is a brief comparison between MAP-3100 and MAP-3120.