Main Thread: Logical gates → Registers → Program execution (memory and CPU) → Operating system → Intercommunication through Ethernet → Routing protocols in a network → IP protocol at different scales
TL;DR The IP protocol allows different kinds of networks to interconnect.
It always amazes me how routers can route a packet from me to any IP address in the world. How is it so intelligent? Later I realized there was a metaphor that would make more sense to me
We will look at IP routing at different scales of networks in this post.
This is a typical local area network (LAN) scenario where the network is for a limited space.
Your internet service provider (ISP) provides you with internet access. They give you a cable of some sort
The ISP sends you WAN analog signals.
There is a device called a Modem that demodulates the ISP WAN signals into Ethernet signals.
There is a router that connects to your modem. Your router provides wired or wireless access for your devices.
Intercommunication within a LAN has been discussed in the last post.
In a medium size company, you might have a spacious office on one floor, multiple floors of a building, or multiple buildings that are closed by.
A single router won't cut it. The network is inefficient, if not infeasible, when all devices broadcast to each other.
The network needs to be divided into multiple parts for easier management. Each piece is called a subnet.
A subnet can be created using physical separation or a VLAN.
There will be routers that aggregate the subnets. So in essence, all devices can still form a LAN.
To ensure network coverage, you need multiple routers placed at strategic locations in your offices.
Wireless Access Point (WAP) is convenient for extending the outreach of routers and providing wireless coverage.
WAP is sometimes preferred over wifi routers for easier management.
Possible signal flow:
ISP network → ISP modem → (wifi) router
You will have a large corporate network to manage when you have a company that spans multiple regions or even continents.
Each office connects to the local ISP but uses a dedicated network backbone that's not shared with the Internet.
It uses the MLPS which is fast and reliable but expensive. Think of it as dedicated two-way highway traffic.
SD-WAN is becoming more dominant. It provides centralized WAN management by software, leveraging different kinds of hardware to optimize traffic control.