Hi Friends! Welcome to the course on Computer Networks and Internet Protocols. The course is designed for undergraduate engineering as well as post graduate MCA and MSc.IT students. The course describes the idea of computer networks and protocols used in the current networks mostly the TCP/IP suite of protocols and a few other supporting protocols. The course sticks to the conventional path of describing components of the network called layers one after another. However, it also ventures into a few emerging networking solutions which work in a cross layer design fashion, packet classification, MPLS or Multi-Protocol Label Switching, IoT or Internet of Things and SDN or Software Defined Networks, etc. Packet classification and SDN also throws some light on how modern day networks demand traffic engineering and how that can be addressed.   The course describers the conventional layered design of computer networks, how different protocols works at different layers and how different functions of different layers are carried out. Starting from how Ethernet and Wireless networks work in the physical layer, it describes how the frames are constructed, errors are corrected and detected, how flow is controlled at data link layer, the course also throws some light on how the CRC and Hamming code techniques are used for the same. The course has a special module to describe how data link and transport layer protocols are designed and work. How the packets are routed across networks is described in network layer processing description. Different routing algorithms like Link State and AODV are explained next. The transport layer description includes TCP functioning, how UDP provides connectionless communication and how SCTP provides the best of both the worlds is also described. The application layer description includes description of various application layer protocols like SMTP, FTP, HTTP and DNS. The final lag of the course throws light on two of the emerging technologies which are threatening to change the conventional networking model. Using MPLS for providing different routing services based on labels, using SDN for providing special quality of services and detailed administration level control for traffic engineering is provided next. How the conventional networking model is divided into multiple planes and how that enables handling heterogeneous devices and diversified functioning in an automated manner is described next. The final three modules throw some light on IoT and related networking protocols, especially mesh networks which is commonly used in IoT and protocols for routing through mesh networks.