LAN : Topologies, Ethernet, Hub, Switches Explained

Hello Ultimates! Today we will learn about LAN.
If two or more computers share any resources like Internet connection, printers, scanners etc. they form a small network called a Local Area Network.
Well this kind of networks are often found in places such schools, cybercafes, colleges and offices where they have many computers.
For example, in a office employees have to work together, they need to share things like printers, documents, pictures etc. so they need connect their computers with each other.
Before starting this article I want tell you that when computers are connected with cables and wires it is called a LAN (Local Area Network) but if they are connected to a wireless router (e.g. a WiFi router) then that type of network is called a WLAN (Wireless Local Area Network).
In common practice we call both networks as LAN but in this article we will stick to cabled LAN only.
So there are several ways of connecting these computers with cables and these ways are called topologies.
Like there is BUS Topology (its rare nowadays though):
bus topology in LAN
In bus topology all computers are connected with a single cable. If a a computer sends something to the another computer, the data is sent to all the computers which causes decrease in performance when we talk about applying bus topology in larger networks. Moreover, if the cable gets damaged somewhere the whole network will be down.
Then there is Mesh Topology:
mesh topolgoy in LAN
In mesh topology, each computer is connected to all the other computers by a separate cable. So if computer/cable stops working the network keeps working.
And we also have Star Topology:
star topology in LAN
All the computers are connected through a device named Hub. If one computers stops working the network stays alive but if central hub gets down the whole networks gets down.

Wait…whats a hub?

Well this is a hub:
what is a hub
Hub is device which is used to connect two or more computers with each other.
As you can see in the photo above, it has ports (physical port) in which you can insert your cables to connect your computers together.
Well hubs have a problem, when they receive a data packet it doesn’t know which computer is its destination, so it sends the data packet to all the computers and the computer requested it accepts it and all the other computers reject it. As it neither knows about MAC Address, nor about an IP Address, it is said to be work in the first layer of the OSI model.
When more then one computers tries to connect it causes a “collision” which corrupts the data which means two pair of computers cant talk to each other simultaneously is they are using a Hub.
Then there is device which is a better version of a Hub, it is called a switch:
what is a switch in LAN
Yeah I know it looks like a hub but the difference lies inside.
A switch has a memory to store the MAC addresses by which it can tell what is the MAC address of the computer connected on port number 1, port number 2, port number 3 and so on.
When some data arrives it reads the MAC Address from it and sends it to the port where the desired computer is connected.
As it can read MAC Addresses we can say its in Layer two of the OSI model.
Ethernet is protocol (set of rules) which is used in LAN to control the transmission of data and defines wiring and signaling standards for the physical layer of TCP/IP protocol.

That’s all folks! I hope you understood what you read in this article.
If you have any queries feel free to ask in comments.

Also Read: A Sniffing Tutorial That Was Missing From The Internet

About the author


I am Somdev Sangwan also known as D3V. I am n00b and I love computers and hacking. I am a python freak and your friendly neighborhood hacker.


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