A switch is a device to connect networked devices together where the data is received from multiple input ports and is channeled out to the devices that are intended to receive it. Network switches are used for similar functionality as hubs but each data packet is examined and processed only to the destination device instead of simply sending the data to all output ports. Network switches are used to connect different network types and to connect multiple switches together a cross over cable is needed.
Network switches are broadly of two types, unmanaged and managed switch.
Unmanagable network switch is a simple device typically used for connecting Ethernet devices together in one location. It is a basic switching device with fixed configuration used for communication between network devices like PCs or network printers. Unmanagable switches do not have any advanced functionalities for custom configuration or monitoring via Simple Network Management Protocol (SNMP). They are cost effective and are suitable for small network connections at home or at workplace.
On contrary, managed switches provide additional ability to configure and manage networks. They allow adjustment of settings of each port and let you configure & monitor travel of data over the network. They are very efficient than network hubs as there is no delay in transfer of data due to message collisions. The switches provide advanced features to control network traffic and can be accessed by a standard web browser or console for efficient management. Some important features supported by managed switches are Spanning Tree Protocol (STP), ether channel, Virtual LANs (VLANs) etc.
Spanning Tree Protocol:
When multiple connections are made between two switches for emergency purposes, it will create a loop which will jam the traffic in the network. To overcome this, Spanning Tree Protocol is used in network switches. Since STP is switched on by default there will be no looping in data transfer. STP disables the ports that are not designated and allows redundant paths in the network to act as backup in case if active links fail.
Another important aspect of managed switches is Etherchannel where multiple ports are grouped together to produce higher bandwidth. EtherChannel can be used when interconnecting switches together or connecting network switch to Ethernet devices etc. Etherchannel supports grouping of multiple active and non-active port links together as a bundle, provided the speed of the ports used for port aggregation are same.
A Virtual LAN allows devices from several networks to work as a single LAN. Some network devices though connected to the same network, work as a subset and act as if it is a separate network. The main purpose is to save network resources and have a partition on Ethernet switch for improved traffic management. Creating VLAN helps to customize the ports accordingly as per the need. However, the number of VLANs we can create is based on ports available in the switch.