CS Online Learning Journal

  Week 5– CST– 311 Intro to Computer Networks Module 5 – The Network Layer This week we studied the Network Layer. We learned about routing and forwarding. Forwarding is when the router moves the packets it receives from its input link to the appropriate output links. Routing is the route determined by routing algorithms which the packet must travel to get to its destination. I like the analogy that the power point slides use to describe forward and routing. If you are traveling through the United States by car from Boston to San Francisco, the routing would be the cities and roads you plan to take to get to San Francisco. Forwarding would be the process of entering and leaving each city because you will enter through a certain road (input port) and must choose which road you need to take to leave the city. We also studied some of the scheduling algorithms which we have become familiar with throughout the program. Because packet loss occurs when packets arrive at a full queue, sc

  Week 4 – CST– 311 Intro to Computer Networks Module 4 –Security in Computer Networks This week we covered Network Security. With secure communication, the goal is to achieve confidentiality, message integrity, end-point authentication, and operational security. Confidentiality means that only the sender and the intended receiver should be able to understand the contents of the transmitted message. Message integrity ensures that the content of the messages is not altered on purpose or by accident during transit. End-point authentication allows the sender and receiver to confirm the identity of the party with which they are communicating. Finally, operational security is how users or corporations can counter attacks like depositing worms into the network, obtaining private documents, and launching DoS attacks. The bulk of this week was focused on cryptography. Cryptography allows the sender to mask the information to prevent intruders from gaining access to the actual information

  Week 3 – CST– 311 Intro to Computer Networks Module 3 –Transport Layer This week we studied the transport layer in more detail. While the Network Layer offers logical communication between hosts, the Transport Layer offers logical communication between processes. The two options made available to the application layer for transport-layer protocols are the User Datagram Protocol (UDP) or the Transmission Control Protocol (TCP). The UDP is an unreliable connectionless transport that does not guarantee data delivery or, if delivered, it does not guarantee that the data will be in order. TCP on the other hand, provides reliable in order delivery as well as congestion control, flow control and connection setup. This chapter also covered multiplexing and demultiplexing. Delivering the data in a transport layer segment to the correct socket is called demultiplexing. Multiplexing is the gathering of data chunks at the source host from different sockets and encapsulating each data chunk

Week 2 – CST– 311 Intro to Computer Networks Module 2 – Application Layer This week we learned about the principles of Network applications. Network application development requires writing programs that run on different end systems and communicate with each other over the network. A good example of this is your web browser program which runs on your computer and the Web server program that runs on the Web server host. Something I found very interesting is that network application developers do not need to write software for the network core devices like routers or link-layer switches because they do not function at the application layer. The two main application architectures for network applications are the client-server and the peer-to-peer (P2P) architectures. In a client-server architecture, the server host is always on and ready to receive requests from many client hosts. In a P2P architecture, the application uses direct communication between pairs of hosts called peers an

  Week 1 – CST– 311 Intro to Computer Networks Module 1 - Computer Networks and the Internet This week was meant for us to get a feel for networking and the terminology. As we progress in this course, we will get into more detail with the subjects covered this week. Chapter one covered the two views of the internet. The “Nuts and Bolts” view contains the ISPs, routers, protocols, and the standards. The “Service” view describes the internet as an infrastructure that provides services to applications like the Web, email, and e-commerce. We also covered the network edge which includes end systems, access networks, and links. The network core includes packet switching, circuit switching, and network structure. There are two fundamental approaches to sending messages through a network of links and switches. The first is packet switching where messages are broken into smaller chunks of data called packets. These packets travel through links and packet switches. The other method is circui