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Purna Pattela
Purna Pattela

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Networking devices 000

#programming #beginners #networking

Internet → Modem → Router → Switch → End Devices (PC, phone, server, etc.)
This flow shows how devices connect to the Internet in a typical network setup, where the modem links to the ISP, the router directs traffic, and the switch allows multiple devices to communicate.

            Internet
               |
             Modem
               |
           Firewall
               |
            Router
               |
            Switch
      /        |       \
Device 1  Device 2   Server Cluster
                       |
                 Load Balancer
                       |
                 Server 1, 2, 3...
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Modem

Modem is often described as the gateway to internet. It is the thing which connect us to the ISP(Internet Service Provider).
We can connect only one device to the modem that can be either single device or router

Internet ↔ Modem ↔ Single device (or router)
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Router

Router is a device which routes the traffic between different networks. Connects local network to the internet through modem.
Takes the responsibility of local IP addressing(DHCP - Dynamic Host Configuration Protocol). Performs NAT(Network Address Translation) so multiple devices can share the same address space(single IP).

Modem → Router → Multiple devices (wired/wireless)
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Switch vs Hub

Hub : simply broadcast the data it received to all connected devices
Switch : relay the data to specific device which is intended

  • Both switch and hub work in LAN(local Area Network)
  • switch reduces the collision improves efficiency 
Hub: Device A → Hub → Devices B, C, D (all get the data)
Switch: Device A → Switch → Device B (only B gets it)
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Firewall

It is a device which safeguards the internet. we can configure it based on our need which type of things to allow through it or block it. It is setup generally in network level

Internet → Firewall → Router → LAN
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Load Balancer

Its a device we use to manage the traffic or load. It is used to distribute the traffic to scale the system.

Internet → Load Balancer → Server 1 / Server 2 / Server 3
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Devices Comparison

Device Name Can Be Hardware Can Be Software Replacement
Modem Yes Rarely (mostly hardware)
Router Yes Yes (e.g., virtual routers like pfSense, VyOS)
Switch Yes Yes (virtual switches in VMware, Hyper-V)
Hub Yes Rarely (mostly hardware)
Firewall Yes Yes (software firewalls like iptables, pfSense, Windows Firewall)
Load Balancer Yes Yes (software like Nginx, HAProxy, AWS ELB)

Conclusion

Understanding network devices—from modems and routers to switches, firewalls, and load balancers—gives a clear picture of how data flows and how networks are structured. Each device has a distinct role: modems connect us to the internet, routers direct traffic, switches manage local communication, firewalls provide security, and load balancers ensure scalability. Together, they form a reliable and secure system that powers both everyday internet use and complex backend applications. For web developers, knowing how these devices interact helps in designing efficient, secure, and scalable systems.

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