Set of devices which are connected with help of wire / wireless, build the network.
What is the modem and What is the router?
Modem is modulator and demodulator ,it converts the analog signal to digital and digital signal to analog. Modem is the superhero that super charges your home with internet.
These signals travel through cables,optical fibers on ocean or wireless network from sky. Modem connects your router to the tower. SO your devices get power.
If you watch a video / a prime video or netflix episode, the modem converts your digital data to analag and transmit/obtain payload from the source and the destination. This communication happens between source and destination, our computer understands the 0 /1 binary (digital signal).
How does modem works?
A Modem is an electronic device which connects different devices by Demodulation and modulation. Modulation is the process of converting data into signals ,so those signals can be transmitted over the network and demodulation is a process that is performed at the reciever side,it is process of recieving the signals back and these signals are converted in digital , digital signals our devices understand and analog signals are transmitted through the wires.
What is router?
Problem: Modem is a device which acts as server for data signals and the router is authoritative to distribute all the signals to your appliance ,for ex- Laptop,Desktop , Tablet and macos.
How router directs traffic?
Router checks for dns server for ip address and checks the packet and those packets or you can say chunks are distributed to the destination devices. It is analogous to light/ or a bulb, they both spread the electric beams towards the destination or The finish line.
Nowdays the some router have the software implementation of switches and hub.In my case,I have purchased internet connection from Airtel and I employ the modem provided by airtel , nowdays the hub ,routers and switches ,they have embedded on one device.
Hub and Switch
Switch controls the one device internet connection, and hub connects to the multiple devices.
Hub is a device that accustomed to connect mutiple devices over the network, it connects the multiple devices with help of ethernet cable. The d-link Dlink 8port hub , help you to connect the multiple devices with interner.
1- Hub can't filter the data.
2- Hub can't identify the data destination source.
3- It broadcasts the message or data to each port.
Hub connects the multiple wires arriving from different branches/ devices, just we have sun, it drops in the sunlight to all over the places to the world. It is just a Crossroad that connects the different routes to all together.
The routing table sends the data to all the ports without filtering,so in your home/office, every device connected with the hub gets the same speed.
Switch connects the device with help of LAN(Local Area Network). If you want to use the internet connection, it requires mac address of the device and you can control the internet speed which you are passing to your device, I will tell one example from our college and
In college campus they have different and faster internet speed, when you visit the hostel , the lag on internet speed happens and this operation is performed with help of switch. They have installed the lan wire for every student intially.
Switch works with Data Link Layer ,so it knows about the every devices and what you are watching, all the information redirected to your ISP.
Understand the firewall by the Airtel spam protection, it identifies that the website / phone number you are dialing / you obtained a wifi call,is he your friend or not.
Firewall is a protection layer ,either software or hardware installed on top of your routers, hubs and switches onto your server. So that it can protect you from Unwanted malwares and virus, it also helps you that this website is reknowned and this is not.
When you install a third party library or framework, do you know, it carry out a lot of vulnerablity with itself, some may be security issues, so this is the major reason ,so that companies install the firewall on their workspace.
What is a Load Balancer and why scalable systems need it?
The load balancer is a server/layer that distributes the traffic to the other servers, you know about horizontal scaling and verticle scaling.
The verticle scaling is the process of increasing the ram and ssd of a single server, so it will increase power of one machine, but if again your project grows then,you require the other resources, providing to much load to a single machine has chances of failure,
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let's understand Horizontal scaling
In case of horizontal scalling ,you can't touch your old system(or server), you purchase more systems and connect with help of hub. So, your server becomes scalable and it has the capacity to handle the more traffic.
Let's take example of ecommerce, you encountered the situation that you have the highest sale on laptop, and lowest on mobile, so you will reduce the servers(devices) which are unused, this is also scale down. When you require that laptops sale is enhancing day by day, if your website crashes, so it will cost your name in market, this is also known as scale down.
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How all these devices work together in a real-world setup?**
Nowdays software companies has implemented the all hardware applications such as switch,modem ,router and hub. There are the software implementation of those also availabe. But some companies have invested the billions of dollars on the traditional hardwares so,they sill use them, but they have modified some of the functionality,like they provide switch that is embedded into the router / modem itself.
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