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...
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)
Router
Router is a device which routes the traffic between different networks. Connects …
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...
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)
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)
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)
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
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
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.