Network Devices in Computer Network

Network Device

Networking devices or networking hardware are physical devices that are required for communication and interconnection between hardware on a computer network.

Hardware devices that are used to connect computers, printers, fax machines and other electronic devices to a network are called network devices. These devices transfer data in a fast, secure and correct way over same or different networks.

Network devices may be inter-network or intra-network. Some devices are installed on the device, like NIC card or RJ45 connector, whereas some are part of network, like router, switch, etc. Let us explore some of these devices in greater detail.

Router

A router is a network layer hardware device that transmits data from one LAN to another if both networks support the same set of protocols. A router is a device like a switch that routes data packets based on their IP address.It receives its data in the form of packets, which are data frames with their destination address added.

A router reads its routing table to decide the best available route the packet can take to reach its destination quickly and accurately. The routing table may be of these two types −

Static − In a static routing table the routes are fed manually. So it is suitable only for very small networks that have maximum two to three routers.

Dynamic − In a dynamic routing table, the router communicates with other routers through protocols to determine which routes are free. This is suited for larger networks where manual feeding may not be feasible due to large number of routers.

Switch

Switch is a network device that connects other devices to Ethernet networks through twisted pair cables. It uses packet switching technique to receive, store and forward data packets on the network. The switch maintains a list of network addresses of all the devices connected to it.

On receiving a packet it checks the destination address and transmits the packet to the correct port.The switch can perform error checking before forwarding data, which makes it very efficient as it does not forward frames that have errors and forward good packets selectively to the correct port only.The data is transmitted in full duplex mode.

Data transmission speed in switches can be double that of other network devices like hubs used for networking.This is because switch shares its maximum speed with all the devices connected to it.This helps in maintaining network speed even during high traffic. In fact, higher data speeds are achieved on networks through use of multiple switches.

Gateway

Gateway is a network device used to connect two or more dissimilar networks. In networking parlance, networks that use different protocols are dissimilar networks. 

A gateway, as the name suggests, is a passage to connect two networks together that may work upon different networking module.They work basically work as an messenger agents that take data from one system, interpret it, and transfer it to another system.

Gateway uses packet switching technique to transmit data from one network to another. In this way it is similar to a router, the only difference being router can transmit data only over networks that use same protocols.

Hub

Hubs connect multiple computer networking devices together. A hub connects multiple wires coming from different branches, for example the connector in star topology which connects different stations. A hub is the simplest in the family of network connecting devices because it connects LAN components with identical protocols.

Hubs do not perform packet filtering or addressing functions; they just send data packets to all connected devices. Also they do not have intelligence to find out the best path for data packets which leads to inefficiencies and wastage. Hub is an broadcasting device that design to connect different computer with each other.

Bridge

Bridges are used to connect two or more hosts or network segments together. The basic role of bridges in network architecture is storing and forwarding frames between the different segments that the bridge connects. They use hardware MAC (Media Access Control) addresses for transferring frames.By looking at the MAC address of the devices connected to each segment, bridges can forward the data or block it from crossing.

Bridges work only at the Physical and Data Link layers of the OSI model. It is a two port device (one for input and one for output).

It is also used for interconnecting two LAN's working on the same protocol.However, bridges filter incoming data packets, known as frames, for addresses before they are forwarded. As it filters the data packets, the bridge makes no modifications to the format or content of the incoming data. The bridge filters and forwards frames on the network with the help of a dynamic bridge table. The bridge table, which is initially empty, maintains the LAN addresses for each computer in the LAN and the addresses of each bridge interface that connects the LAN to other LAN's.

Repeater

A repeater operates at the physical layer. It is job is to regenerate the signal over the same network before the signal becomes too weak or corrupted so as to extend the length to which the signal can be transmitted over the same network.

Repeaters do not amplify the signal when the signal becomes weak, they copy the signal bit by bit and regenerate it at the original strength.