CSS313 Advanced Computer Networks Course Notes PDF

CSS313 Advanced Computer Networks Week 1: Overview of Data Communication Model Fall 2024 Assist. Prof. Eman Sanad 1  The Text Books Class textbooks: Computer Networking: A Top- Down Approach (8th ed.) J.F. Ku...

CSS313 Advanced Computer Networks Week 1: Overview of Data Communication Model Fall 2024 Assist. Prof. Eman Sanad 1  The Text Books Class textbooks: Computer Networking: A Top- Down Approach (8th ed.) J.F. Kurose, K.W. Ross, Pearson, 2020 DATA COMMUNICATIONS AND NETWORKING ,Fourth Edition, Behrouz A. Forouzan 2007 2 Week # Course Contents: Description 1 Overview of data communication model 2 Analysis of Network flow control and congestion control mechanisms 3 Internet Multicasting, NAT, VPN 4 Routing Algorithms – BGP, RIP, OSPF 5 MPLS 6 Data link layer and MAC address 7 ARP protocol 8 QoS: Differentiated and Integrated Services 9 Data Centre Networking Network Function Virtualization -NFV Architecture, Use cases, NFV 10 Orchestration and NFV for 5G. 11 Cloud Computing infrastructure and services 3 IOT, Green Communication Networks Course Evaluation Methodology Grading: Midterm: 30% Quizes: 15% (3 quizzes 5% each) Lab exam and project: 15% Final Exam: 40% Attendance: Attendance for lectures and labs are mandatory 4 4 Data Communication The term telecommunication means communication at a distance. The word data refers to information presented in whatever form is agreed upon by the parties creating and using the data. Data communications are the exchange of data between two devices via some form of transmission medium such as a wire cable. 5 5 Figure 1 Components of a data communication system 6 6 Figure 2 Data flow (simplex, half-duplex, and full-duplex) 7 7  NETWORKS A network is a set of devices (often referred to as nodes) connected by communication links. A node can be a computer, printer, or any other device capable of sending and/or receiving data generated by other nodes on the network. A link can be a cable, air, optical fiber, or any medium which can transport a signal carrying information. Topics discussed in this section: ▪ Network Criteria ▪ Physical Structures ▪ Categories of Networks 8 8 Network Criteria ◼ Performance ◼ Depends on Network Elements ◼ Measured in terms of Delay and Throughput ◼ Reliability ◼ Failure rate of network components ◼ Measured in terms of availability/robustness ◼ Security ◼ Data protection against corruption/loss of data due to: ◼ Errors ◼ Malicious users 9 9 Physical Structures ◼ Type of Connection ◼ Point to Point - single transmitter and receiver ◼ Multipoint - multiple recipients of single transmission ◼ Physical Topology ◼ Connection of devices ◼ Type of transmission - unicast, mulitcast, broadcast 10 10 Figure 3 Types of connections: point-to-point and multipoint 11 11  Geometric representation of how the computers are connected to each other is known as topology. There are mainly four types of topology: ◦ Mesh Topology ◦ Star Topology ◦ Bus Topology ◦ Ring Topology 12 13  In mesh topology each device is connected to every other device on the network through a dedicated point- to-point link.  When we say dedicated it means that the link only carries data for the two connected devices only.  Lets say we have n devices in the network then each device must be connected with (n-1) devices of the network.  Number of links in a mesh topology of n devices would be n(n-1)/2. 14  No data loss  Reliable  Secure  Easy to troubleshoot  Fast communication 15  Amount of wires required to connected each system is tedious and headache.  Since each device needs to be connected with other devices, number of I/O ports required must be huge.  Scalability issues because a device cannot be connected with large number of devices with a dedicated point to point link. 16 17  In star topology each device in the network is connected to a central device called hub.  Unlike Mesh topology, star topology doesn’t allow direct communication between devices, a device must have to communicate through hub.  If one device wants to send data to other device, it has to first send the data to hub and then the hub transmit that data to the designated device.  The central device is known as hub and other devices connected to hub are called clients. Generally Coaxial cable or RJ-45 cables are used to connect the clients to the hub. 18  Less expensive  Easier to install  Cost effective  Robust  Easy to troubleshoot  Reliable 19  If hub goes down everything goes down.  Hub requires more resources and regular maintenance.  Not Scalable 20 21  In bus topology there is a main cable and all the devices are connected to this main cable through drop lines.  There is a device called tap that connects the drop line to the main cable.  Since all the data is transmitted over the main cable, there is a limit of drop lines and the distance a main cable can have. 22  Easy installation.  Less Expensive  Limited failure. 23  Difficultly in fault detection.  Not scalable  Difficult to troubleshoot  Data collision 24 25  Each device is connected with the two devices on either side of it.  There are two dedicated point to point links a device has with the devices on the either side of it.  This structure forms a ring thus it is known as ring topology.  If a device wants to send data to another device then it sends the data in one direction.  each device in ring topology has a repeater.  if the received data is intended for other device then repeater forwards this data until the intended device receives it. 26  Easy to install.  Less expensive.  Easy maintenance. 27  A link failure can fail the entire network as the signal will not travel forward due to failure.  Data traffic issues, since all the data is circulating in a ring. 28 Categories of Networks ◼ Local Area Networks (LANs) ◼ Short distances ◼ Designed to provide local interconnectivity ◼ Wide Area Networks (WANs) ◼ Long distances ◼ Provide connectivity over large areas ◼ Metropolitan Area Networks (MANs) ◼ Provide connectivity over areas such as a city, a campus 29 PROTOCOLS A protocol is synonymous with rule. It consists of a set of rules that govern data communications. It determines what is communicated, how it is communicated and when it is communicated. The key elements of a protocol are syntax, semantics and timing Topics discussed in this section: ▪ Syntax ▪ Semantics ▪ Timing 30 Elements of a Protocol ◼ Syntax ◼ Structure or format of the data ◼ Indicates how to read the bits - field delineation ◼ Semantics ◼ Interprets the meaning of the bits ◼ Knows which fields define what action ◼ Timing ◼ When data should be sent and what ◼ Speed at which data should be sent or speed at which it is being received. 31 Internet protocol stack ◼ application: supporting network applications ◼ FTP, SMTP, HTTP application ◼ transport: process-process data transfer transport ◼ TCP, UDP ◼ network: routing of datagrams from network source to destination ◼ IP, routing protocols link ◼ link: data transfer between neighboring network elements ◼ Ethernet, 802.111 (WiFi), PPP physical ◼ physical: bits “on the wire” 32 ISO/OSI reference model ◼ presentation: allow applications to interpret meaning of data, e.g., application encryption, compression, presentation machine-specific conventions ◼ session: synchronization, check session pointing, recovery of data transport exchange network ◼ Internet stack “missing” these layers! link ◼ these services, if needed, must physical be implemented in application ◼ needed? 33  source message M application segment Ht M transport datagram Hn Ht M network frame Hl Hn Ht M link physical link physical Encapsulation switch destination Hn Ht M network M application Hl Hn Ht M link Hn Ht M Ht M transport physical Hn Ht M network Hl Hn Ht M link router physical 34 Application architectures possible structure of applications: ◼ client-server ◼ peer-to-peer (P2P) 35 Client-server architecture server: ◼ always-on host ◼ permanent IP address ◼ data centers for scaling clients: ◼ communicate with server ◼ may be intermittently client/server connected ◼ may have dynamic IP addresses ◼ do not communicate directly with each other 36 P2P architecture ◼ no always-on server peer-peer ◼ arbitrary end systems directly communicate ◼ peers request service from other peers, provide service in return to other peers ◼ self scalability – new peers bring new service capacity, as well as new service demands ◼ peers are intermittently connected and change IP addresses ◼ complex management 37 Connection-oriented protocol ◼ A connection-oriented service is a network service that before delivering data over the same or separate networks, a connection-oriented service is used to establish an end-to- end connection between the sender and the receiver. ◼ It employs a handshake approach ◼ Packets are forwarded to the to establish a connection between receiver in the same sequence the user and the sender before as they were sent by the delivering data across the network. sender. ◼ As a result, it is also recognized as a reliable network service. ◼ Example: TCP protocol 38 Connectionless protocol ◼ In a network system, connectionless service is used to send data from one end to the other without establishing a connection. ◼ As a result, there is no need to establish a connection before delivering data from the transmitter to the receiver. ◼ As a result, we might conclude that the data packet does not follow a ◼ It is not a dependable network predefined path. service since it does not guarantee the passage of data ◼ Due to network congestion, the packets to the recipient, and transmitted data packet is not data packets can arrive at the received by the recipient in receiver in any sequence. connectionless service, and the data may be lost. ◼ Example: UDP, IP protocols 39 Reliable and Unreliable Connections ◼ The transport layer uses reliable and unreliable connections to transfer data between two devices in a network. ◼ A reliable connection provides guaranteed data delivery, but it takes more time for data delivery than an unreliable connection. ◼ For reliable connections, it uses TCP (Transmission Control Protocol). ◼ The TCP protocol uses a three-way handshake, windowing, and sequence numbers for guaranteed data delivery. ◼ An unreliable connection delivers data faster than a reliable connection, but it does not provide any guarantee for data delivery. 40