A switch is where various network devices join to. A switch is a smart repeater that can have a large number of port interfaces. A consumer level switch has 4 to 8 ports while an enterprise level switch can have 32 or more port interfaces.
A switch only sends out repeated signals to the correct host by using the destination MAC address. A switch looks at the destination MAC address of the traffic. Then it sends the traffic to only the appropriate interface on that switch, rather than sending it to all the interfaces on that switch. This switching lookup is done in the switch hardware called Application-Specific integrated circuit (ASIC).
A switch is very scalable and therefore is the core of an enterprise network.
Each port on the switch has it’s own separate network and gets to use full bandwidth so does not have to share bandwidth when routing message.
Some switches come with routing capability (as in a router) and these are called a “multilayer switch” or a “layer 3 switch.”
Managed
Managed switches provide advanced functionality. For example you can set up different VLANs on different ports. You can connect different switches together in a trunk, which is also known as 802.1Q.
Managed switches can be configured to prioritize traffic. For example, you can set voice traffic to receive a higher priority.
Managed switches support redundancy by using Spanning Tree Protocol (STP).
A network management station will be able to communicate with devices on a managed switch using SNMP.
Port mirroring is also supported. This means that traffic can be mirrored on one port to another so that a network analyzer can connect to the port and capture packets from the copied port for troubleshooting.
Unmanaged
An unmanaged switch provides very little configuration options. An unmanaged switch provides very basic functionality and is just plug and play with very minimal set up required. There’s no configuration utility. You just basically plug in your devices to the unmanaged switch and they’ll all be able to communicate with each other in the same VLAN. Unmanaged switches also aren’t able to integrate with external protocols. For example, devices on an unmanaged switch wouldn’t be able to communicate back and forth to a management station via SNMP.
The advantage of using an unmanaged switch is that it is less expensive than a managed switch.