In networking there are several kinds of devices which are used to serve the purpose. In general we call them network devices. The common devices are
A hub is a simply a connector to extent the network. Here extend means it will only extend the network as infrastructure. A network hub does not do any logical work. It just connects two devices. Suppose there are a wire extension is required and somehow the wire is disconnected in a certain distance then we can connect a hub to reestablish the connection using wire. The working principle of this device is it just broadcasts the data and when the recipient is found then it serves the data to that device.
A network repeater is a two port device. It does not do any logical work either. Its primary work is to keep the signal strength up so that it can arrive to the next hope. The working principle of this device is to collect the signals from the previous signal and generate exactly same signals and send it to the next hope. It collects the signal bit by bit and generates according to those bits and makes sure that it is strong enough to exist till it arrives to the next device.
Modem is a device which is used for modulation and demodulation at the same time. Modulation and demodulation are occurred within the device so that it can define the data in a telephone system. When we start to send the data than it usually modulates the data using some algorithm and it sends to the recipient and then the opposite party will demodulate the data and finds the actual data.
Bridge is a device which connects two sub networks of a bigger network. Suppose we have more than one network within a network then using bridge we can connect those networks and use all those networks as one network. This device makes the network administrators work a lot easier. That’s why bridge is a very popular device for a network administrator.
Switch is a multiport device which works almost like a hub but a far better than a hub according to working principle. This is kind of intelligent version of hub. This is a layer 2 device which is data link layer. On this layer the devices do not broadcast data to the whole network. It will record MAC address and then it will read the packets, only then it will start working. Also it will not send corrupted data. We also have layer 3 switch and layer 3 switches works as a router or we can say that it is a mini router.
Router is a layer 3 device and it can operate all the works related to routing. Routing is the most essential and mandatory work in networking. Router usually introduces and keeps a continuous connection within two networks. This is a very delicate work with so many filter and network address issues. Router usually keeps a record of different networks so that it can communicate faster.
Brouter is a device which is a combination of bridge and router. It can work as a bridge and at the same it can work as a router. It have special feature to filtering. Just because of this special feature it is a lot popular among network administrators.