Computer Networking Essentials for DevOps: Learn How the Internet Works


In the world of DevOps, understanding computer networking is crucial. Whether you're deploying applications, managing cloud infrastructure, or troubleshooting connectivity issues, networking fundamentals play a key role. In this blog, we'll explore:
How the Internet Works
The OSI Model
The TCP/IP Model
Important Networking Protocols
Hands-on Demo with AWS (VPC, Subnets, CIDR, Gateways, Route Tables)
1. How Does the Internet Work?
The internet is a global network of interconnected computers and servers that communicate using standardized protocols. Here's a simplified breakdown:
Devices (Clients & Servers): Your laptop (client) requests data from a server (e.g., a website hosted on AWS).
IP Addresses: Every device has a unique IP (e.g.,
192.168.1.1
or2001:0db8:85a3::8a2e:0370:7334
for IPv6).DNS (Domain Name System): Converts human-readable names (e.g.,
google.com
) to IP addresses.Routers & Switches: Direct traffic efficiently across networks.
Packets: Data is broken into small chunks (packets) and reassembled at the destination.
2. The OSI Model (7 Layers)
The Open Systems Interconnection (OSI) model standardizes network communication into seven layers:
Layer | Name | Function | Example |
7 | Application | User interfaces & services | HTTP, FTP, DNS |
6 | Presentation | Data translation, encryption | SSL, TLS |
5 | Session | Manages connections | NetBIOS, RPC |
4 | Transport | Reliable data transfer | TCP, UDP |
3 | Network | Routing & logical addressing | IP, ICMP |
2 | Data Link | Physical addressing (MAC) | Ethernet, ARP |
1 | Physical | Raw bit transmission | Fiber, Wi-Fi |
Why it matters for DevOps?
Helps troubleshoot network issues (e.g., is the problem at Layer 3 (IP) or Layer 4 (TCP)?
Security policies (e.g., firewalls at Layer 4 vs. Layer 7).
3. The TCP/IP Model (Simplified OSI)
The TCP/IP model is the practical implementation used on the internet:
Layer | Name | OSI Equivalent | Key Protocols |
4 | Application | Layers 5-7 (App, Pres, Session) | HTTP, FTP, SSH, DNS |
3 | Transport | Layer 4 (Transport) | TCP (reliable), UDP (fast) |
2 | Internet | Layer 3 (Network) | IP, ICMP, ARP |
1 | Network Access | Layers 1-2 (Physical, Data Link) | Ethernet, Wi-Fi |
Key Differences:
TCP/IP combines OSI’s top 3 layers into Application.
More aligned with real-world internetworking.
4. Important Networking Protocols
Protocol | Layer | Purpose |
HTTP/HTTPS | Application (7) | Web communication (port 80/443) |
DNS | Application (7) | Domain → IP resolution (port 53) |
TCP | Transport (4) | Reliable, connection-oriented |
UDP | Transport (4) | Fast, connectionless (e.g., video streaming) |
IP | Network (3) | Logical addressing (IPv4/IPv6) |
ICMP | Network (3) | Diagnostics (ping, traceroute) |
ARP | Data Link (2) | Maps IP → MAC address |
5. AWS Networking Demo (VPC, Subnets, Gateways, Route Tables)
Let’s deploy a simple AWS network to see these concepts in action.
Step 1: Create a VPC (Virtual Private Cloud)
A VPC is your private network in AWS.
Go to AWS VPC Console → Create VPC.
Set IPv4 CIDR block (e.g.,
10.0.0.0/16
→ 65,536 IPs).
Step 2: Create Subnets
Subnets divide your VPC into smaller networks.
Example:
Public Subnet (
10.0.1.0/24
) – For web servers.Private Subnet (
10.0.2.0/24
) – For databases.
Step 3: Set Up an Internet Gateway (IGW)
Allows public subnet to access the internet.
Attach IGW to your VPC.
Step 4: Configure Route Tables
A route table defines traffic rules.
For public subnet, add:
Destination: 0.0.0.0/0 (Internet) Target: igw-xxxx (Internet Gateway)
Step 5: Launch an EC2 Instance
Deploy an EC2 instance in the public subnet.
Assign a public IP.
Test internet access (
ping
google.com
).
Step 6: Security Groups & NACLs
Security Group (Firewall for instances): Allow SSH (port 22), HTTP (80).
NACL (Subnet-level firewall): Stateless rules for inbound/outbound.
Expected Result:
EC2 in public subnet can reach the internet.
Private subnet remains isolated (unless using NAT Gateway).
Conclusion
Understanding networking is essential for DevOps engineers. From the OSI model to AWS VPCs, these concepts help in:
Deploying scalable apps (e.g., microservices in subnets).
Troubleshooting connectivity (e.g., checking route tables).
Securing cloud environments (e.g., NACLs, Security Groups).
Try replicating the AWS demo yourself! 🚀
Further Learning:
Let me know in the comments if you'd like a deeper dive into any topic! 🚀
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Written by

Sdeep
Sdeep
👋 Hello! I'm passionate about DevOps and I'm proficient in a variety of cutting-edge technologies and always motivated to expand my knowledge and skills. Let's connect and grow together!