Material
Good reference links
YouTube play list
Free NPTEL [Reference]
Free NPTEL-IIT [Reference]
Online Courses :
The bits and bytes of Computer Network [Coursera]
Computer Communication Specialization [Coursera]
List of books
Text books:
1. Data communication & Networking, Behrouz Forouzan, McGraw-Hill:
Reference books:
1. Computer Network, Andrew S. Tanenbaum, Fourth Edition, Prentice Hall
2. Data and Computer Communications, William Stallings, Prentice Hall