Computer networks, networking fundamentals, mạng máy tính
7/19/2008 1 Module 2: Networking Fundamentals 7/19/2008 2 Outline 2.1 Networking Terminology Data networks Network history Networking devices Network topology Network protocols Local-area networks (LANs) Wide-area networks (WANs) Metropolitan-area networks (MANs) Storage-area networks (SANs) Virtual private network (VPN) Benefits of VPNs Intranets and extranets 2.2 Bandwidth Importance of bandwidth Analogies Measurement Limitations Throughput Data transfer calculation Digital versus analog 2.3 Networking Models Using layers to analyze problems in a flow of materials Using layers to describe data communication OSI model OSI layers Peer-to-peer communications TCP/IP model Detailed encapsulation process 7/19/2008 3 2.1 Networking Terminology 7/19/2008 4 Data networks There was no efficient way of sharing data among multiple microcomputers Floppy disks Sneakernet created multiple copies of the data If two people modified the file and then tried to share it, what will happen ?. Businesses needed a solution to address the following problems: How to avoid duplication of equipment and resources How to communicate efficiently How to set up and manage a network networking technology could increase productivity while saving money. In the mid-1980s, each company that created network hardware and software used its own 7/19/2008 5 Data networks (cont.) company standards Network technologies were incompatible with each other Difficult to communicate with each other This often required the old network equipment to be removed to implement the new equipment. LAN standards provided an open set of guidelines for creating network hardware and software, the equipment from different companies could then become compatible. In a LAN system, each department of the company is a kind of electronic island. WANs could connect user networks over large geographic areas. 7/19/2008 6 Network history 7/19/2008 7 Network history (cont.) 7/19/2008 8 Network history (cont.) 7/19/2008 9 Networking devices Equipment that connects directly to a network segment is referred to as a device. End-user devices : They include computers, printers, scanners, and other devices that provide services directly to the user. Network devices : They include all the devices that connect the end-user devices together to allow them to communicate. End-user devices that provide users with a connection to the network are also referred to as hosts. The host devices can exist without a network, but without the network the host capabilities are greatly reduced. A NIC is a printed circuit board that fits into the expansion slot of a bus on a computer motherboard, or it can be a peripheral device. It is also called a network adapter. 7/19/2008 10 Networking devices (cont.) Network devices provide transport for the data that needs to be transferred between end-user devices. Network devices provide extension of cable connections, concentration of connections, conversion of data formats, and management of data transfers. Networking devices : Repeater : Repeaters regenerate analog or digital signals distorted by transmission loss due to attenuation. The purpose of a network repeater is to regenerate and retime network signals at the bit level. This allows them to travel a longer distance on the media. A repeater does not perform intelligent routing like a bridge or router. Hubs : They concentrate connections. In other words, they take a group of hosts and allow the network to see them as a single unit. This is done passively, without any other effect on the data transmission. Active hubs not only concentrate hosts, but they also regenerate signals. Multi-ported Repeater.