CS402: Computer Communications and Networks

Read the introduction to Chapter 2 and section 2.1, "Services and Protocols", on pages 5–20. You may notice that some information in the textbook is not completely up-to-date. The Wikipedia article below includes some more recent information for you to explore. Also, Figure 2.1 in the textbook shows the number of hosts on the Internet only through 2007. Updated information is available at https://www.isc.org/solutions/survey/history.

The second chapter of Computer Networking: Principles, Protocols, and Practice serves as an introduction to networking as you link across time to review the development of standards and technologies that comprise today's wired and wireless information systems entangled in the Web.

As you read this section, consider the following questions: What is the difference between a service and a protocol? What is topology and what is a transmission mode? What is the purpose of each?

As noted above, this article discusses some more recent information regarding these topics.

Read the introduction to section 2.2 and section 2.2.1, "The reference models", on pages 20–23. As you read, consider how we use layers as a model for describing network processing. Layers are the foundation for studying computer networks. You must understand how to work with layers to be able to describe the flow of a data request to its destination, and how the reverse occurs when the destination sends a response.

Read these lecture notes. As you read, pay special attention to the history and different versions of internetworking structure based on TCP/IP protocols.

Read Sections 2.2.3 and 2.3, "The OSI Reference Model" and "Organisation of the Book", on pages 24–25.

As you read, consider the following questions: Which came first, the OSI model or the TCP/IP model? Which layers in the OSI model appear to be missing in the TCP/IP stack? Where are they in the TCP/IP model?

A Wide Area Network (WAN) is a computer network that extends over a large geographical distance. Read this article for more details about WANs. There are many different kinds of WAN, such as ATM, Cable, Dial-up, DSL, Frame Relay, ISDN, Leased line, SONET, X.25, and SD-WAN, to name a few.

Read this article and take notes on the following terms and concepts: different transmission media, such as linear media, bounded media, and isotropic media; copper wire; coaxial cables; and fiber optic media.

Read the introduction to Section 3.1, "Principles", on pages 27–30. Stop at Section 3.1.1.

As you read, consider these questions: What is the client-server model? What is the function of the client? Where does the server reside?

Note: On page 28, the textbook lists the binary code of A as "A : 1000011b". This is incorrect. The binary code for A should be: "A : 1000001b".

Read this article. As you read, note that most languages/platforms provide libraries that convert from network order to host order in the event that the host does not agree.

Read Section 3.1.1, "The Peer-to-Peer Model", on page 30. This section introduces the peer-to-peer model, which will be discussed further.

As you read, try to answer the following question: how does the peer-to-peer model change or improve the client-server model discussed in the previous section?

Read Section 3.1.2, "The Transport Services", on pages 30–31.

This section discusses how networked applications are built on top of the transport service. There are two main types of transport services: connectionless and connection-oriented. What are the similarities and differences between the two types of services?

Read section 3.2.1, "The Domain Name System", on pages 32–37.

In order to access a website, you need to know the website's IP address. IP addresses can be somewhat cumbersome and difficult to remember, since they are simply four numbers separated by periods (e.g., 120.755.3.9). The Domain Name System (DNS) is the application that has solved this problem by allowing us to use "human readable" names for websites. What is the domain name for your home page on your work, school, or home LAN? What is the IP address for each one? Which would you rather use, the IP address or the domain name?

Read this article. The Domain Name System is a networking protocol. It converts domain names to the IP addresses, which are needed to locate and identify computer services and devices with the underlying network protocols.

Read Section 3.2.2, "Electronic mail", on pages 37–46. In this section you will look at the e-mail application and explore two of the more popular protocols: SMTP and POP3. How does e-mail work? How long does it take for a message to reach its destination? Then what happens?

Read Section 3.2.3, "HyperText Transfer Protocol", on pages 46–55. HTTP is a text-based protocol, in which the client sends a request and the server returns a response. In this section link across the World Wide Web via your textbook to see how this is accomplished.

Read this article. As you read, pay special attention to the definitions of managed devices, agent, and network management system (NMS). At the same time, try to explain what kind of message flows are defined in NMS.

Read this article. As you read, pay attention to how SSH protocol is defined and the difference between FTP and SSH-based Secure FTP.

Read this tutorial on how to make a simple network application program with Python socket. It is recommended that you download and install Python from the Python official website (http://www.python.org/) and run the sample program.

Read Section 3.4, "Summary", on page 61.

This unit discusses the evolution of the Internet from IPv4 to IPv6 in application processing. Why was the change from 32-bit IPv4 to128-bit IPv6 critical for the application layer?

Read from Section 3.5, "Exercises", to the end of Chapter 3, on pages 61–65. These exercises further expand the key principles in this chapter. If you are a computer professional, you will enjoy the challenges and higher-level discussions in this section. For the novice, just wander through the presentations and spend more time on the topics that are meaningful to you.

It will take a significant amount of time for you to finish these exercises. We recommend that you schedule 4 hours and attempt a few challenging exercises.

Follow these steps in order to control your computer from a mobile device.

Follow these steps to control your computer from a mobile device via Virtual Network Computing. Virtual Network Computing is a graphical desktop sharing system. It uses Remote Frame Butter Protocol to control another computer remotely. Even if you choose not to download the above apps, reading this article is still valuable as it provides an explanation of the difference between RDP and VNC.

Read the introduction to Chapter 4 and Section 4.1, "Principles of a Reliable Transport Protocol", on pages 67–87.

This section discusses the transport protocol in perfect and imperfect network service environments in terms of interactions with the Service Data Unit (SDU) at various stages of the transmission between sending and receiving nodes. What happens to your transmission when the environment is perfect? If your data gets corrupted by transmission errors, lost, reordered, or duplicated, then what happens? Explore the links in your textbook for a better understanding of what goes wrong in cyberspace and the mechanisms used to repair impacted activity.

Read section 4.2, "The User Datagram Protocol", on pages 87–89.

The UDP allows several applications running on a host to exchange SDUs with several other applications running on remote hosts. This section explores the checksum process and how the UDP accomplishes this multiprocessing.

Read the introduction to Section 4.3, "The Transmission Control Protocol", on pages 89–90. Stop at Section 4.3.1.

Almost every Internet application relies on the TCP in the transport layer. In this section you will discover how your favorite Internet activity exchanges data around the world. Then in the following subunits, you can travel with your data as it streams to its destination and back.

Read section 4.3.1, "TCP Connection Establishment", on pages 90–95. As you read, be able to describe the three-way handshake used by TCP to establish a connection.

Read section 4.3.2, "TCP Connection Release", on pages 95–97. As you read, make sure you are able to identify and explain the two types of connection release.

Read the beginning of section 4.3.3, "TCP Reliable Data Transfer", on pages 97–98. Stop when you get to "Segment Transmission Strategies".

Read "Segment Transmission Strategies" on pages 98–99. Stop at the "TCP Windows" section.

This section of your textbook presents the Nagle Algorithm. What is it, and what two strategies does it provide for data transmission?

Read "TCP Windows" on pages 99–100. Stop at "TCP's Retransmission Timeout". As you read, consider the following questions: What is a TCP window according to the information provided in this section of your textbook? How does a TCP window improve processing in the transport layer?

Read section 4.3.3, "TCP's Retransmission Timeout", on pages 100–102. Stop at "Advanced Retransmission Strategies".

Follow the path in this section of your textbook to see how the TCP retransmission timeout improves transport performance.

Read "Advanced Retransmission Strategies" on pages 102–105. Stop at "TCP Congestion Control".

As you read, consider the following questions: What is the exponential back off and how does TCP use it? What is the delayed acknowledgement strategy in TCP? What is the fast retransmit heuristic as utilized by TCP? What is the SACK option?

Read "TCP Congestion Control" on pages 105–113. Stop at the summary.

TCP's congestion control is one of its best performance control features. This section explains this feature and how it improves performance in the transport layer.

Read this article, which explains why we need the new SCTP protocol and how it works.

Read this webpage to understand how RTP is used for streaming multimedia data. As you read, pay special attention to how RTP protocol is different from TCP protocols and how it is used for multimedia data transport.

Read the summary of chapter 4 on pages 113–114.

The transport layer relies on TCP mechanisms to recover from the errors of the network layer. The chapter 4 summary reviews the strategies at each stage of the transmission.

Read through the practice exercises on pages 113–126. These exercises further expand the key principles in this chapter. If you are a computer professional, you will enjoy the challenges and higher-level discussions in this section. If you are a novice, explore the presentations and spend more time on the topics that are meaningful to you.

Read the introduction to chapter 5 and the beginning of section 5.1, "Principles", on pages 127–129. Stop at section 5.1.1, "Organisation of the Network Layer".

The network layer includes the datagram and virtual circuit modes, the separation between the data plane and the control plane, and the algorithms used by routing protocols.

As you read this section, it is important to understand the purpose of the router and the use of the packet in enabling you to send data and receive the response. How does the packet interact with the router?

Read section 5.1.1, "Organisation of the Network Layer", on pages 129–132.

What are the two internal organizations used in the network layer? When are each used? What is a datagram? Explore this section of your textbook to see how a datagram is used in the network level. Compare and contrast the datagram organization with the virtual circuit discussed in this section.

The concept of hop-by-hop forwarding is this section. What does this concept have to do with the routing table? What is the difference between the data and control planes?

Read the beginning of section 5.1.2, "The control plane", on page 132. Stop at "Static routing".

In this section, the textbook explains how the control plane maintains the routing table. The three techniques to accomplish this are static routing, distance vector routing, and link state routing. As you explore the next three subunits describing each one in detail, note the advantages and disadvantages of each technique. How does each method deal with link and router failures?

Read "Static Routing" on pages 132–133. Stop at "Distance Vector Routing", which you will read below. As you read, consider the following questions: What is static routing? What are its advantages and disadvantages?

Read "Distance Vector Routing" on pages 133–137. Stop at "Link State Routing", which you will read below. As you read, consider the following questions: What is distance vector routing? What are its advantages and disadvantages?

Read "Link State Routing" on pages 137–140. Stop at section 5.2, "Internet Protocol". As you read, consider the following questions: What is link state routing? What are its advantages and disadvantages? How does link state routing handle link and routing failures?

Read this article for more details about the Bellman-Ford routing algorithm. This routing protocol is used in RIP, OSPF, and BGP.

Read this article for more details about the Dijkstra routing algorithm. What is the Dijkstra Algorithm? How is the Dijkstra Algorithm used in link state routing? Like the Bellman-Ford algorithm, this routing protocol is used in RIP, OSPF, and BGP.

Review this demonstration, which discusses how Djikstra's algorithm is implemented step-by-step.

Read the introduction to section 5.2, "Internet Protocol", on pages 140–141. Stop at section 5.2.1 "IP Version 4", which you will read below.

In this section we will explore the Internet Protocol (IP) to discover how IP enables the applications running above the transport layer (UDP/TCP) to utilize any of the different datalink layers available.

Read section 5.2.1, "IP version 4", on pages 141–150.

This section starts with a discussion of IP version 4 before exploring network addressing in more detail. As you read, consider the following questions: What are two of the problems with IP version 4 that led to the development of the Classless Interdomain Routing (CIDR) architecture? How does CIDR improve the scalability of the IP routing system?

Read section 5.2.2, "ICMP version 4", on pages 151–157. Sometimes a router or the destination host has to inform the sender of the packet of a problem that occurred while processing that packet. In the TCP/IP protocol suite, this reporting is done by the Internet Control Message Protocol (ICMP). How are these messages generated by the ICMP?

Read section 5.2.3, "IP version 6", on pages 157–164. As the popularity of the Internet grew exponentially, it became necessary for an expanded addressing architecture, IP version 6 (IPv6). This section discusses how IPv6 has resolved a number of routing issues while becoming the new standard.

Read section 5.2.4, "ICMP version 6", on pages 164–166. ICMPv6 is the companion protocol for IPv6, just as ICMPv4 is the companion protocol for IPv4. ICMPv6 is used by routers and hosts to report problems when processing IPv6 packets. In addition, ICMPv6 is used when auto-configuring addresses. This section discusses messaging for IPv6.

Read the introduction to section 5.2.5, "Middleboxes" on page 166. Stop at "Firewalls", which you will read below. As you read, consider the following questions: What is a Middlebox? Why do we need them?

Read "Firewalls" on pages 166–168. Stop at "NAT", which you will read below. As you read, consider the following questions: When you first used your computer to access the Internet, what was the first security technique you heard about? How does a firewall protect your system from the "evil-doers" lurking on the Internet?

Read "NAT" on pages 168–169. Stop at section 5.3 "Routing in IP networks".

Large corporations and government agencies prefer their networks to be private (that is, not seen on the Internet). In this section, explore the concept of private networks to learn how their need to communicate with the outside world and with specific machines under certain conditions has resulted in NAT; the mechanism that allows private networks to communicate openly with the outside world. How does NAT work?

Read the introduction to section 5.3, "Routing in IP Networks", on page 170. Stop at section 5.3.1, "Intradomain Routing", which you will read below. Routing protocols will be discussed in terms of two classifications: intradomain and interdomain. What are the differences between these classifications?

Read "RIP" on pages 171–172. Stop at "OSPF", which you will read below. As you read, consider the following questions: What is RIP? What are the features of the RIP protocol? How does RIP meet the objectives of intradomain routing? What are its weaknesses?

Read "OSPF" on pages 172–175. Stop at section 5.3.2 "Interdomain routing", which you will read below. As you read, consider the following questions: What is OSPF? What are the features of the OSPF protocol? How does OSPF meet the objectives of intradomain routing? What are its weaknesses? How is OSPF different from RIP?

Read section 5.3.2, "Interdomain Routing", on pages 175–194. As you read, consider the following questions: What are the objectives of interdomain routing? What is the difference between transit and stub domains? What are some of the relationships you can expect to find in an interdomain routing policy?

Describe the BGP. How does BGP differ from the intradomain protocols RIP and OSPF that you've studied? What messages might the BGP generate? What is router convergence? Why is router convergence necessary? How is router convergence handled by the BGP?

Read this tutorial to understand congestion management at different levels: end-to-end, router assisted, and pricing based.

Read from section 5.5, "Exercises", through the end of chapter 5, on pages 195–209. These exercises expand the key principles in this chapter. If you are a computer professional, you will enjoy the challenges and higher-level discussions in this section. If you are a novice, explore the presentations and spend more time on the topics that are meaningful to you.

This is a software tool that helps you perform networking experiments on your computer. Download and try it with a few simple examples, such as exercise 5 (page 196) and 6 (page 197) in the textbook.

Follow the steps detailed in this document. You will learn how to scan for network devices in your local area network using a mobile device, in this case, the "LAN Scan HD" app.

Read the introduction to chapter 6 and the beginning of section 6.1, "Principles", on pages 211–212. Stop at section 6.1.1 "Framing", which you will read below.

The datalink layer uses the service provided by each of the different technologies found in the physical layer to send and receive bits between directly connected devices. The datalink layer receives packets from the network layer. What are the two main services provided by the datalink layer? Why are these services necessary?

Read section 6.1.1, "Framing", on pages 212–213. As you read, consider the following questions: What is the framing problem? What service does the datalink layer provide to resolve this problem?

Read section 6.1.2, "Error Detection", on pages 213–214. Datalink mechanisms also help solve problems related to detecting transmission error.

Read the beginning of section 6.2, "Medium Access Control", on pages 214–215. Stop at section 6.2.1, "Static Allocation Methods", which you will read below.

A computer network environment faces additional problems beyond the framing and error detection issues that are resolved in the datalink layer. What are these problems? How does the Medium Access Control algorithm(s) function in any of the computer network topologies?

Read section 6.2.1, "Static Allocation Methods", on pages 215–216. As you read, consider the following questions: What is static allocation? What are some of the static allocation methods utilized in the datalink layer to share resources in a computer network? Describe each method and how each handles the available resources.

Read this article, which provides a more detailed examination of the ALOHAnet structure.

Read section 6.2.2, "ALOHA", on pages 216–217. The University of Hawaii addressed the problem of sharing resources with its network of remote island campuses in a unique way. This description of the ALOHAnet explores their solution.

Read section 6.2.3, "Carrier Sense Multiple Access", on pages 217–218. The ALOHA solution has been enhanced by CSMA. As you read, be able to describe CSMA and how it works to share computer network resources.

Read section 6.2.4, "Carrier Sense Multiple Access with Collision Detection", on pages 218–222. In a wired environment, both ALOHA and CSMA performance are better able to detect collision. Can you explain why that is?

Read section 6.2.5, "Carrier Sense Multiple Access with Collision Avoidance", on pages 222–225. CSMA/CA is found in the Wi-Fi environment. How are collisions avoided?

Read section 6.2.6, "Deterministic Medium Access Control algorithms", on pages 226–228. Some applications are sensitive to the time delay of transmissions. Deterministic Medium Access Control algorithms have been used to resolve this problem. Explore this section to see some of the deterministic algorithms.

Read the beginning of section 6.3, "Datalink Layer Technologies", on page 229. Stop at section 6.3.1, "The Point-to-Point Protocol", which you will read below.

It would take a library full of volumes to discuss all of the technologies used on the Internet. Your textbook has condensed this information into a discussion of six major categories. The following subunits address the datalink services of these technologies.

Read section 6.3.1, "The Point-to-Point Protocol", on pages 228–230.

Read the beginning of section 6.3.2, "Ethernet", on pages 230–234. Stop at "Ethernet switches", which you will read below. MAC addresses are the datalink services found in an Ethernet environment.

Read "Ethernet Switches" on pages 234–237. Stop at "The Spanning Tree Protocol (802.1d)", which you will read below. As you read, consider the following questions: What is an Ethernet switch? How does it function in the datalink layer? How does it utilize Medium Access Control mechanisms?

Read "The Spanning Tree Protocol (802.1d)" on pages 237–240. Stop at the "Virtual LANs" section, which you will read below. The spanning tree protocol is a distributed standard that is used by switches to reduce the network topology to a spanning tree by eliminating all cycles. Explore the examples in your textbook to see how this technology processes frames in the datalink layer.

Read "Virtual LANs" on pages 240–241. Stop at section 6.3.3, "802.11 wireless networks", which you will read below. As you read, consider the following question: How do Ethernet switches create virtual LANs?

Read section 6.3.3, "802.11 Wireless Networks", on pages 241–246. Wi-Fi is a very popular wireless networking technology. There are hundreds of millions of Wi-Fi devices, resulting in multiple wireless networking standards that use different frequency ranges and different physical layers. Explore the wireless revolution into the datalink layer in this section.

Read section 6.4, "Summary", on page 246. In chapter 6, you explored how Local Area Networks pose a problem for transporting frames since several devices share the same transmission channel. A variety of Medium Access Control algorithms have been necessary to regulate the access to the transmission channel by reducing collisions: ALOHA, CSMA, CSMA/CD, and CSMA/CA. Review the key technologies discussed in this section.

Watch this video for more details about networking devices such as switch,hub and routers. A network switch is a multiport network bridge that uses hardware addresses to process and forward data at the data link layer (layer 2) of the OSI model. A router is a networking device that forwards data packets between computer networks. An Ethernet hub, active hub, network hub, repeater hub, multiport repeater, or simply "hub", is a network hardware device for connecting multiple Ethernet devices together and making them act as a single network segment.

Read section 6.5, "Exercises", through the end of chapter 6, on pages 246–247. These exercises expand the key principles in this chapter. If you are a computer professional, you will enjoy the challenges and higher-level discussions in this section. If you are a novice, explore the presentations and spend more time on the topics that are meaningful to you.

Follow the steps detailed in this document in order to control your computer from a mobile device.

Read this article, which discusses one of the most popular network applications: Voice over IP. There are quite a few industry protocols for Voice over IP; one of the most popular and widely accepted is IETF protocol SIP. As you read, pay special attention to the registering and calling process.

Read this article, which discusses another popular network application: Video over IP. This protocol enables us to have videoconferences over the Internet. As you read, pay special attention to the different IPTV techniques, such as video on demand (VOD), live television, and time-shifted television.

Read this lecture. As you read, pay special attention to DoS attacks, intrusion, hijacking, Web authentication attacks, and weakness in Internet architecture.

Read this article and take notes on the following popular terms: IaaS (Infrastructure as a Service), PaaS (Platform as a Service), SaaS (Software as a service), MaaS (Monitoring as a Service), CaaS (Communication as a Service), and XaaS (anything as a Service).

Watch this video, which discusses the advantages and disadvantages of cloud computing and when it makes sense for companies to move to the cloud.

Read this article and take notes on the following: authentication, authorization, and accounting (AAA) and where they are used.

Read this article and take notes on the following popular terms: Remote Authentication Dial In User Service (RADIUS), roaming, realms, and proxy operations.

Read these articles and take notes on the following: Terminal Access Controller Access-Control System (TACACS), Terminal Access Controller Access-Control System Plus (TACACS+), and how they are used in AAA Protocols.

Read this article and note the following terms: directory service, X.500, distinguished name (DN), and LDAP operations.

Read this article and note the following terms: directory service, X.500, distinguished name (DN), and LDAP operations.

Read this article and take notes on the following popular terms: reliable network, reliable multicast, unicast protocols, and reliability properties.

Follow the steps detailed in this document, which will instruct you how to use port-scanning techniques to administrate a large network.