Network And Network Devices
BSc CSIT Graduate
Introduction to Network
If any two or more than two entities are connected to communicate with each other, then that connection is called as network. Example of network can be social network (connection between two or more people), network or highways etc.
Similary, when the two or more computers are connected, it is called computer network. Computer network make communication possible for computers. The network of multiple computer networks is internet. We need certain physical appliances to establish a network for computers , these physical appliances are know as network devices. Some of network devices are : Router, Modem, Switch, firewall etc. these devices help you to access the internet.
Function of Network Devices
Enabling communication between computers
Managing and controlling data traffic to avoid congestion
Amplifies weak signal to boost speed and extend network coverage
Provice secure connection
Network Devices
When you open a website, your data travels through multiple devies before reaching its destination.
your device genereates data(like http request)
NIC converts data into signal to travel over local network
Hub or switch or access point directs data within your local network
router choose the best path for data to leave your network
modem converts your LAN signal into analog signal suitable for transimsiion over the ISP medium then you get connected to the internet
Finally your request reach to the server and it gerenates the response and it come back to you same way it went.
1. NIC
NIC stands for network interface card. This is the chip(used to be an external card) inside your device that makes your device able to connect to network physically or wirelessly. NIC is present in every network-connected device. NIC has mac address assigned to which is required for the communication inside local aread network. NIC converts data to the electrical signal(if you are connecting with ethernete cable) or radio waves(if using wi-fi) so it can travel over the medium. The receiving device’s NIC converts the signal back into digital form tha computer can understand
2. HUB
HUB Is used to connect multiple computers in a local area network. When hub receives data from any devices connectd to it’s port, it broadcast the data to all other ports. It does not know MAC address, IP address. It is dumb. So every device connected to its port wil get the data but only the intended device will receive it, others just ignore. The transmission mode in hub is dubplex, meaning sending and receiving of data can not be done simultaneouly.
3. Repeater
When signal travels through the medium like wire, air they might lose weight with the distance. In order to make the signal sharp as the original we need some extra work to do. This is where repeater are used. Repeater does not understand data but they just signals. Let’s suppose you max length for a ethernet cable is 100m, if you need 200m you have to put a repeater in between.
4. Modem
Word modem came from the work it does; modulation and demodulation. Modem converts signal(generated by NIC) from your network to the form requried by your ISP’s physical medium and vice verca. It acts as a translator between your network and your internert. It is placed between your router and ISP connection. Modem provides internet to the network that is connected through a hub or switch.
5. Switch
Switch is the better version of HUB that is used to connect all the fevices is a local area network. It is much smarter. It forwards data only tot the device that needs it using mac address. It stores mac of all the connected devices and upon receiving a message from sender it checks mac address of the message and then sends the message to the receiver that mathces the mac address.
6. Bridge
Bridge is a network device that connects two LAN segments and manage traffic between them. You can think it as a small overpass connecting two neighborhood allowing only relevant traffic to pass. Bridge uses MAC address to decide whether to send data between LAN segments. Suppose you have LAN1 and LAN2. Device A in LAN1 wants to send data to device B in LAN2. Bridge check MAC address table: if the destination MAC is in the other LAN , it forwards the data, and if same it blocks the data.
7. Access Point (AP)
AP is a networking device that allows wireless devices to conne t to a wired network (LAN). AP is connected to a switch or router using ethernet cable. Wireless devices connet to the AP via wi-fi. AP forwards wireless traffic to the wired network, and vice-versa.
8. Router
Router is a device that connects two or more networks and forwads data between these based on IP address. It connets a LAN to the WAN or Internet. It maintains MAC address of local devices using an ARP(address resolution protocol) table. When a router receives a packet it checks the destination IP address. If destination IP belongs to the local network the router forward the packet by creating frame with the destination device’s MAC address and sends it to the switch. If the destination IP is outside the local network , the router forwards to ISP gateway by encapsulatin it in a new frame with the ISP gateway’s MAC address.
9. Firewall
Firewall is network device that sits between. your local network and the outside world to control and filter the traffic. It monitors and filters incomming and outgoing traffic according to predefined rules. This is the best place to control the traffic because it is right in between the router and outside world. All of the traffic or packets have to pass through this. Imagine you wanna put a security guard at your home to block all of the unknown person to enter, where would you let him stand? at the main gate from where the any unknown person can come right? So firewall is also a gatekeeper for you LAN.
10. Load Balancer
It is a networking device that distributes network traffic across multiple servers to make sore no single server get overloaded. Load balancers are used in the server side. Server use it to share the load. Suppose you have 3 servers. If any user requuest come load balancer will direct it to the server that has less requests, to make sure user get response faster and no server become overloaded.
