Computer networks networking fundamentals

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.