In most cases, introducing a Layer 3 switch reduces the number of network devices you need to monitor, manage, and maintain. You reduce or eliminate the need for dedicated routers in your network by pushing the Layer 3 function to either the firewall or the Layer 3 switch. The layer 2 switches collect the data from core switches, identify the type of data packet and the address of the access device. This means that each segment is a self-contained portion of the network that communicates with the "outside world" only when needed. Layer 2 switches use a connected device's MAC address while a layer 3 switch. To make sense of what and where network monitoring is necessary, it helps to break it down by the OSI model — particularly focusing on Layer 2 (Data Link), Layer 4 (Transport), and Layer 7 (Application).