Computer Networking Essentials for DevOps: Learn How the Internet Works

SdeepSdeep
4 min read

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:

  1. How the Internet Works

  2. The OSI Model

  3. The TCP/IP Model

  4. Important Networking Protocols

  5. 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 or 2001:0db8:85a3::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:

LayerNameFunctionExample
7ApplicationUser interfaces & servicesHTTP, FTP, DNS
6PresentationData translation, encryptionSSL, TLS
5SessionManages connectionsNetBIOS, RPC
4TransportReliable data transferTCP, UDP
3NetworkRouting & logical addressingIP, ICMP
2Data LinkPhysical addressing (MAC)Ethernet, ARP
1PhysicalRaw bit transmissionFiber, 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:

LayerNameOSI EquivalentKey Protocols
4ApplicationLayers 5-7 (App, Pres, Session)HTTP, FTP, SSH, DNS
3TransportLayer 4 (Transport)TCP (reliable), UDP (fast)
2InternetLayer 3 (Network)IP, ICMP, ARP
1Network AccessLayers 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

ProtocolLayerPurpose
HTTP/HTTPSApplication (7)Web communication (port 80/443)
DNSApplication (7)Domain → IP resolution (port 53)
TCPTransport (4)Reliable, connection-oriented
UDPTransport (4)Fast, connectionless (e.g., video streaming)
IPNetwork (3)Logical addressing (IPv4/IPv6)
ICMPNetwork (3)Diagnostics (ping, traceroute)
ARPData 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 ConsoleCreate 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!