Networking Fundamentals Semester 1 – Module 2 Module Objectives: Explain and understand the importance of bandwidth in networking Explain the difference between bandwidth and throughput Calculate data transfer rates Explain why layered models are used to describe data communication Explain the development of the OSI model and its advantages Identify each of the seven layers of the OSI model Identify the four layers of the TCP/IP model Describe the similarities and differences between the two models Identify devices used in networking Understand the role of protocols in networking Define LAN, WAN, MAN, and SAN Explain VPNs and their advantages Describe the differences between intranets and extranets Why Create Data Networks? Business applications were written for microcomputers that caused the need to share data Address the following three problems: How to avoid duplication of equipment and resources How to communicate efficiently How to set up and manage a network Computer networking does two main things: Increase productivity Save money LAN, MAN, & WAN • Local Area Network (LAN) – Connects a group of computers in a small area – What are Advantages & Disadvantages? • MAN & WAN – Connects multiple LANS – Allows data to be shared over a large distance Quick Network History Facts • late 1960s and 1970s – “smaller” computers called minicomputers were created. – DoD begins to develop large, reliable, WAN for military and scientific reasons (ARPANET). • mid-1980s PC users began to use modems (point-topoint) to share files with other computers. • 1990s – The WAN developed by the DoD eventually became the Internet as we know it. – WWW is Born • 2000s – 2001 - Internet users exceed 110 Million End User vs Network Devices • End User Devices – Workstations – Servers – Printers – Scanners • Network Devices – Repeater/Hub – Bridge – Switch – Router What do all of these devices have in common? Network Devices •Repeater - a non-intelligent network device used to regenerate a signal. •Hubs - take a group of hosts and allow the network to see them as a single unit. Multi-port repeater. •Bridges - converts network data formats, performs basic data transmission management, and provides connections between LANs, thus making each part of the network more efficient. •Workgroup Switches - add more intelligence to data transfer management by determining if data should remain on a LAN and transfering data only to the connection that needs it. •Routers - have all the capabilities listed above, including regenerating signals, concentrate multiple connections, convert data transmission formats, and manage data transfers. They can also connect to a WAN, which allows them to connect LANs that are separated by great distances. Network Topologies • Physical – Bus – Ring – Star – Extended Star – Hierarchical – Mesh • Logical – Token Passing • Token Ring • FDDI – Broadcast Network Protocols • Protocol - a formal description of a set of rules and conventions that govern a particular aspect of how devices on a network communicate. • Protocol suites - collections of protocols that enable network communication between hosts. • Protocols control all aspects of data communication, which include the following: – – – – – How the physical network is built How computers connect to the network How the data is formatted for transmission How that data is sent How to deal with errors Who creates and maintains Protocols? LANs • LANs consist of the following components: – – – – – Computers Network interface cards Peripheral devices Networking media Network devices • Some common LAN technologies include the following: – Ethernet – Token Ring – FDDI WANs • WANs are designed to do the following: – Operate over a large and geographically separated area – Allow users to have real-time communication capabilities with other users – Provide full-time remote resources connected to local services – Provide e-mail, Internet, file transfer, and e-commerce services • Some common WAN technologies include the following: – – – – – – Modems Integrated Services Digital Network (ISDN) Digital subscriber line (DSL) Frame Relay T1, E1, T3, and E3 Synchronous Optical Network (SONET) Can you think of an example of a MAN? SANs • SANs offer the following features: – Performance – SANs allow concurrent access of disk or tape arrays by two or more servers at high speeds. This provides enhanced system performance. – Availability – SANs have built-in disaster tolerance. Data can be duplicated on a SAN up to 10 km (6.2 miles) away. – Scalability – A SAN can use a variety of technologies. This allows easy relocation of backup data, operations, file migration, and data replication between systems. VPNs • The following are the three main types of VPNs: – Access VPNs - provide remote access for mobile and small office, home office (SOHO) users to an Intranet or Extranet. Access VPNs use various technologies to securely connect users. – Intranet VPNs - use dedicated connections to link regional and remote employees to an internal network over a shared infrastructure. – Extranet VPNs - use dedicated connections to link business partners to an internal network over a shared infrastructure. Intranets & Extranets • Intranet - designed to permit LAN users who have access privileges to servers housing information such as financial, graphical, or textbased data. Typically servers are web servers which are accessed by web browsers. • Extranets - refer to applications and services that are Intranet based, and use extended, secure access to external users or enterprises. This access is usually accomplished through passwords, user IDs, and other application-level security. Bandwidth • Bandwidth is defined as the amount of information that can flow through a network connection in a given period of time. – Bandwidth is limited by the laws of physics and by the technology – Bandwidth is not free – Bandwidth requirements are growing rapidly – Bandwidth is critical to network performance How do we Measure Bandwidth Throughput • Throughput refers to actual measured bandwidth, at a specific time of day, using specific Internet routes, and while a specific set of data is transmitted on the network. • The following are some of the factors that determine throughput: – – – – – – – Internetworking devices Type of data being transferred Network topology Number of users on the network User computer Server computer Power conditions Data transfer Calculation Would it take less time to send the contents of a floppy disk full of data (1.44 MB) over a 56Kbps dial-up line, or to send a 1GB MPEG file over a Cable Line that is capable of 10Mbps? Digital vs Analog • Analog – The basic unit of analog bandwidth is hertz (Hz). – kilohertz (KHz), megahertz (MHz), and gigahertz (GHz) – Uses a frequency • Digital – Information always sent out as bits – Uses channels Network Models & Layers • The OSI and TCP/IP models have layers that explain how data is communicated from one computer to another. Rules of Layered Models • Both Sending and Receiving hosts must use the same protocols • Each layer communicates with its counterpart, independently of the other layers OSI Model • Open System Interconnection (OSI) • Created by International Organization for Standardization (ISO) • primary model for network communications What are the advantages of a layered model? Physical Layer Data Link Layer Network Layer Transport Layer Session Layer Application Layer Peer-to-Peer Communication • Protocol Data Units (PDU) • Data Packets – data as a whole TCP/IP Model • Created by U.S. Department of Defense • IP points the way for the packets, while TCP provides a reliable transport. Labs 2.3.6 Lab Exercise: OSI Model and TCP/IP Model - In this lab, the student will learn the four layers of the TCP/IP model and the seven layers of the OSI model to the four layers of the TCP/IP model. 2.3.7 Lab Exercise: OSI Model Characteristics and Devices - In this lab, the student will learn the seven layers of the OSI model and the characteristics, functions and keywords relating to each layer.