Anoop Rajoriya

Posted on Jan 20

Understanding Network Devices

#networking #beginners #chaicode

Content List

Real world setup with networking devices
Modem and how it connect network to internet
FireWall and why security lives here
Router and how it directs traffic
Switch vs Hub and how local networks works
Load Balancer and why scalable system need it

Translating Signals

Modem is sorthand of Modulation and Demodulation its a simple device sit between ISP and digital devices within homes or offices network. When this digital device send any request to internet these request goes in digital signals formate (0s & 1s). The problem is ISP don't talk in wave signal formate (analog signal) so we need a device who translate these digital language to analog language and back to digital language to make communication possible.

The Modem use technique called Modulation and Demodulation to translate this signal formate into each other formate.

Modulation: Process translating digital signals (0s & 1s signals) into analog signals (wave signals).
Demodulation: Process translating analog signals to digital.

Packets Inspaction

The ISP is the part of WAN (Wide Area Network) which is wast network or digital world. In this world there are lots of harmfull things exist like malicious code, viruses, and hackers which can riding along with data packets and can harm our entire critical data or devices. So for that we use Firewall this is the system sit behind the modem it block harmful incoming requests and block the outgoing requests carrying critical data.

Firewall is a system that can be physical device (Hardware Firewall), software installed in computer (Software Firewall), and cloud service.

Firewall use a ACL (Access Control List) keep set of rules used to decide which traffic is allowed to denied. It inspact every incoming packates to check is it requested information or not, only allow if the requested else denied to keep network secure.

Deciding Optimal Path

We all know internet is the wast network in there dozens of small networks, devices, servers exist if need to go to specific device in here we can't find that so we need a some type of guider or mapper who tell the optimal and sorter path to reach a specific device.

So the device named Router does a same things. Router is a smart device which sit behind the firewall or sometims it hold the firewall part inside itself. The job of router is to guide the data packets within the network.

To guide data packets with in network efficiently it assing private IP address to all device connected to it and utilize single public IP address enable the communication. This srategy hide the internal network device for outside. It use Routing Table which holdes the all other routers public IP address within the WAN, to decide the shorter or efficient path.

Note: Every data packets contain header and payload. header contains source ip, destination ip, MAC address etc. payload contain actual data.

when data packet arrive to router it see the destination IP address and check in there routing table, there are two cases apear:

If record found, calculate efficient shorter path and direct to its calcualted port.
if record not found, then it direct to its nearest router through exit port who might know its detination address.

The Final Path

Some private network have dozens of device connecting all these devices to router can overloade the router. To reducing the burden on a router Hubs and Switches are used. These device always used within the personal network or private network to connet device to it, its job is to efficiently deliver the data to end device.

Hubs are the dum device the use bradcasting message deliver to each device connected to it causing slow delivery or exposing message to everyone. Its use half duplex mode support one direction communication at a time causeing a packets collision.
Switches are the smarter than hubs a new generation device. It use MAC address list, a physical device address used to identified each device uniquely. No nead broadcasting message to every one, safely deliver message to end device. Its use full duplex mode support bi-directional communication at a time.

In modern setup Switches are mostly used because of secure delivery and full duplex support.

Suppressing load

In client-server architecture when dozens of user make request at the same time to same server, server must be getting overloade and some times it crash or fails, causeing milions of money loss in big industies. To solve that, there are a system named Load Balancers are used.

Load Balancer job is to sit front of croud making requests on server guid them to currently active working servers. It allow Horizontal Scalling instead adding resources (ram, cpu) on same server (Veritcal Scalling), adding more cheap servers.

When lots of requests comming at the same time, Load Balancer efficiently balance the loads among these servers evenly for doing that it use algoritms like Round Robin, Ip Hash. It check the server status only healty servers getting traffic or unhealty servers was deleted.

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