Network concepts and Programming from Scratch

This course is thorough. We explain the design, discuss the code flow and then guide the audience how to implement the particular concept design in detail in a step by step manner. All you need is a Linux OS running on your system to do this course.

Who should do this course ?

This course is meant for UG Computer science students, job seekers and professional developers. This is MUST do course for those who want to join MNCs as a developer. The topics covered in this course are of utmost importance from interviews aspects and students graduating in computer science and looking to seek an opportunity in MNCs as a developer should have Networking concepts at his/her finger tips.

Better to have done Networking under graduate course, not mandatory.

Job seekers trying for the position of Networking developers in product based MNCs

System software development including Networking is an evergreen area. Internet will not going to be doomed ever.

Pre-requisite

There is no pre-requisite for this course, however, it shall be advantage if you know a little of C. We designed this course assuming student is a complete beginner in Networking and we raise the level of course gradually as we move from Basic to advance Networking concepts.

Also, Please just do not sit and watch my codes. Write your own codes, even if it is same as mine !

We have a strong reasons to choose C as a language for this course:

1. The entire core networking development work is being done in C in industry. So, this reason alone is good enough that you should learn network development in C if you are aiming to join industry as a network protocol developer.

2. Network equipment need to interact with underlying hardware - the ASIC chips. What could be a better language other than C when it comes to interact and program the hardware.

3. C is middle level language - not as low as assembly, neither as high as Java/Python. In C, its the programmer's responsibility to write every line of code to get the task done, unlike Java/Python which provides rich rest of libraries to do the most tasks for you. Using High Level Languages for learning network programming would obscure the low level details of networking - that is what is going behind the scenes. If you are are beginner in network programming, you must learn things from scratch and only C provides you the opportunity to do that. So, you must do all your assignments in C.

4. Networking is all about cooking up the packets and sending it out of wire. C will allow you to cook packets exactly the same way as you would like them to appear on wire. Lot of Bit level programming.

5. If you are a beginner in Networking, pls refrain from learning network programming in High Level Languages such as Java Or Python. It is not job oriented thing to do in networking domain.

No Third Party libraries

Whatever logic you implement, you need to implement it from scratch. This course do not suggest taking help of any third party library to get the jobs done. Use of external libraries completely defeats the purpose of the course. However, it is recommended to use third party libraries for commonly used data structures such as linked lists/Trees/Queues etc which saves a lot of time implementing these data structures.

Curriculum

0. Setting up Linux Development Environment on your machine

For those who are not familiar with Linux Installation/environment
Resource : Get started with Linux Development environment

1. OSI Model Vs TCP/IP Stack

Data Encapsulation and Data Decapsulation
Headers Cascading
Ingress and egress Journey of packet through a TCP/IP Stack
Big Picture

2. Multi-node setup environment on your machine

Setup Multinode Cluster of Virtual machines on your machine
Local and Remote Subnets
Layer 3 Route Semantics
Configure Layer 3 routes in nodes
Understand L3 Routing table semantics

3. Subnetting and IP address

Understand Subnets
Differentiate between local and remote subnets
IP Address assignment scheme/policy
Data Delivery
Understand MAC addresses and their use
Calculation of Networking ID, Broadcast address and Cardinality of a subnet
Understand the relationship between L3 routers and Subnets
Understand Point-to-Point links
MAC layer and IP rules of packet rejection/acceptance
Broadcast Addresses
Resources : Helpful Link for IP Address Conversions - Link1
Resources : Helpful link for IP address conversion - Link2

4. Layer 2 Networking concepts

L3 Router as a gateway to subnet
Protocol Identifier fields at each layer
Ethernet header format
How Ethernet hdr makes L2 routing possible
ARP (Address resolution protocol)
ARP table population and use
Step by Step ARP protocol functioning
Assignment on ARP
Layer2 Switch - How it works
MAC address table
Step by Step description of L2 Switch functioning
Problem of Layer Thrashing

5. Layer 3 Networking concepts

Relationship between Layer2 and Layer3 routing
Explained the dependency of two layers over each other
Configuring Layer 3 routing table
Semantics of a Layer 3 route
Layer 3 route look up
Concept of Longest prefix match
IP Header - fields you should know
Network Layer Operations
Step by Step description of L3 routing routing
Resources : Layer 3 Routing - Another Comprehensive Example
Loopback interface - purpose and configuring loopback interface
Exercise on Layer 3 route installation, routing and forwarding of traffic

6. Network troubleshooting tools

How ping works - ICMP protocol description
Networking applications troubleshooting utilities - ping, wireshark, tcpdump
Capturing the packets and examine its contents using tcpdump

7. Transport Layer

Layer Goals
Contrasting Layer2, Layer 3 and Layer 4 together
TCP Vs UDP
Resources : Read more about connection Oriented and Connection-less Service
Concept of Headers stacking
Concept of port numbers
Linux System call interface

8. Socket programming concepts

Socket Programming Design
Select System call
Accept System call
Concept of Multiplexing
Server State machine
Resources : TCP Vs UDP

9. Application Layer

Different ways to implement Sockets
on Top of Transport layer
on Top of Network Layer
on Top of Data link layer
Designing HTTP Webserver from scratch
HTTP Webserver Implementation
Custom application sockets

10. IP-in-IP Encapsulation/Tunneling

What is IP-in-IP Encapsulation ?
Why we need IP-in-IP Encapsulation ?
How Encapsulated packet is routed in the network ?
Two scenarios using IP-in-IP Encapsulation

11. Wheel Timers - Periodic Packet based Dispatchers

Wheel Timer Design
Implementation
Demonstration
Coding Assignment

12. Concept of TLVs

What are TLVs
Why we need TLVs
Writing a TLV decoder
Benefits of TLVs in Network communication
STREAMS - Data Structure
TLV (De)Serialization using STREAMS