The Access layer is the level where host computers are connected to the network. The Distribution layer acts as an aggregation point for all the Access layer devices. The Core layer connects all Distribution layer devices and reliably and quickly switches and routes large amounts of traffic.

What is the access layer?

The access layer, which is the lowest level of the Cisco three tier network model, ensures that packets are delivered to end user devices. This layer is sometimes referred to as the desktop layer, because it focuses on connecting client nodes to the network.

What is the core layer?

The Core Layer is often known as the backbone or the foundation network because all other switches rely on it. Its purpose is to minimize the delay in the delivery of packets and so responsible for fast and reliable transportation of data across a network.