What is Switching? What is Network Switch?

Switching: Every time in computer network you access the internet or another  computer network outside your immediate location, your messages are sent through a maze of transmission media and connection devices. The mechanism for moving information between different computer network and network segment is called switching in computer network.

For example: - whenever a telephone called is placed, there are numerous junctions in the communication path that perform this movement of data from one network onto another network.

Network Switch

In computer network Switches and Bridges are the layer 2 computer network devices. Once the number of users began to push the limits of a single computer network segment, there was a need to create a new segment to link two computer networks together a device called bridges accomplished this. basically the bridges have 2 ports, one for each computer network, bridges actually inspect the data that passes through them and make decisions about whether to send it to the other computer network or not.

This decision is based on the MAC address in Ethernet networks and on the ring no. in Token Ring Networks. Because of this behavior (specifically that bridges read and act on the data in the Layer 2 headers of each frame), hence Bridges are layer 2 devices. 

As networks become larger, and the amount of data transmitted by each computer increased, segmenting networks became even more important. 2 port bridges were no longer sufficient then switch began as multiport bridges and are considered layer two devices.

Most switches have 12 to 24 ports but many are modular can have several hundred ports. Switches can handle several conversations at same time each 100base -TX port on a switch can send and receive frames at the same time, so switches are  Full Duplex and hubs are Half-Duplex.

Router is a Layer 3 Device :- Routers are created to segregate broadcast domains.Roters act as boundary between broadcast domains. Routers read and make decisions based on layer 3 headers, Like:

- TCP/IP or IPX headers. So they become layer3 devices. A routers function is to inspect incoming packet and determine whether it belongs to local network or to a Remote Network,

If a local packet is determined then there is no need of routing and if a Remote packet is determined then it will route that packet according to the routing table other wise the packet will be discarded.