Network Switch

An ethernet switch lets you connect multiple devices to the same network segment, but does NOT connect the network segments.

Cisco Switches have numbered ports that are connected using Ethernet or RJ45 cables. Specialized ports for Gigabit Ethernet and SFP are also available.

Network switches are better than network hubs in the sense that each port on the switch is it's own isolated collision domain, making a point-to-point full-duplex connection between any two nodes. This concept is known as microsegmentation.

Collisions can only happen if the port where it happened is operating in half-duplex mode, which is triggered when a legacy network card or a network hub is connected to the switch.

The switch uses the same broadcast address across all ports unless configured to use vLANs.

Features

There are two main types of network switches: managed and unmanaged. While network switches work out of the box, only managed switches can be configured with settings that the network administrator wishes to set. Unmanaged switches don't have those capabilities.

Configurable settings include:

active ports
reset the IP address of the switch
Quality of Service => give priority to something (e.g. voice/video packets for communications)
manage and configure vLANs
manage and configure ports that have PoE enabled

Switches can also be stackable: meaning that groups of switches can be networked together and are able to operate as a group, manageable as a single logical component.

Switches can be either fixed or modular: meaning that either they come with a set number of ports or there are plug-in slots for extended port counts.