NSH0503/01/11041 Overview Computer Network Technology By Diyurman Gea

NSH0503/01/11042 Data Networks Data networking solutions –Local-area networks –Wide-area networks

NSH0503/01/11043 Networking Devices Equipment that connects directly to a network segment is referred to as a device. These devices are broken up into two classifications. The first classification is end-user devices. The second classification is network devices.

NSH0503/01/11044 Network Topology Network topology defines the structure of the network. The physical topology, which is the actual layout of the wire or media, and the logical topology, which defines how the media is accessed by the hosts for sending data.

NSH0503/01/11045 Network Protocols Protocol suites are collections of protocols that enable network communication from one host through the network to another host. A protocol is a formal description of a set of rules and conventions that govern a particular aspect of how devices on a network communicate.

NSH0503/01/11046 LAN Operate within a limited geographic area Allow many users to access high-bandwidth media Provide full-time connectivity to local services Connect physically adjacent devices

NSH0503/01/11047 LAN Devices

NSH0503/01/11048 WAN Technologies Analog modems Integrated Services Digital Network (ISDN) Digital Subscriber Line (DSL) Frame Relay Asynchronous Transfer Mode (ATM) E carrier series: E1, E3 Synchronous Digital Hierarchy (SDH)

NSH0503/01/11049 WAN Devices

NSH0503/01/ Metropolitan-Area Networks (MANs) A MAN is a network that spans a metropolitan area such as a city or suburban area. A MAN usually consists of two or more LANs in a common geographic area.

NSH0503/01/ Virtual Private Networks (VPNs) A VPN is a private network that is constructed within a public network infrastructure such as the global Internet.

NSH0503/01/ Benefits of VPNs A VPN is a service that offers secure, reliable connectivity over a shared public network infrastructure such as the Internet. VPNs maintain the same security and management policies as a private network. They are the most cost-effective method of establishing a point-to-point connection between remote users and an enterprise customer's network.

NSH0503/01/ VPN Types There are three main types of VPNs: Intranet VPNs Extranet VPNs Access VPNs

NSH0503/01/ Intranets and Extranets Intranets are designed to permit access by users who have access privileges to the internal LAN of the organization. Extranets refer to applications and services that are Intranet based, but that use extended, secure access to external users or enterprises.

NSH0503/01/ OSI Reference Model The application (upper) layers –Layer 7: Application –Layer 6: Presentation –Layer 5: Session The data-flow (lower) layers –Layer 4: Transport –Layer 3: Network –Layer 2: Data link –Layer 1: Physical

NSH0503/01/ The Purpose of OSI Model It breaks network communication into smaller, simpler parts that are easier to develop. It facilitates standardization of network components to allow multiple-vendor development and support. It allows different types of network hardware and software to communicate with each other. It prevents changes in one layer from affecting the other layers so that they can develop more quickly. It breaks network communication into smaller parts to make learning it easier to understand.

NSH0503/01/ Why a Layered Model?

NSH0503/01/ Using Layers to for Communication Source, destination, and data packets –All communications originate at a source and travel to a destination. –Information that travels on a network is referred to as a data, packet, or data packet.

NSH0503/01/ Media –Telephone wires (UTP) –Category 5 UTP (used for 10BASE-T Ethernet) –Coaxial cables –Optical fibers (thin glass fibers that carry light) Protocol –All devices on a network need to speak the same language. –Set of rules that makes communication both possible and more efficient. Using Layers to for Communication

NSH0503/01/ Layers with Functions

NSH0503/01/ The Upper Layers Application –User interface –Examples – Telnet, HTTP Presentation –How data is presented –Special processing, such as encryption –Examples – ASCII, EMCDIC, JPEG Session –Keeping different applications’ data separate –Examples – Operating system/application access scheduling

NSH0503/01/ The Data-Flow Layers Transport –Reliable or unreliable delivery –Error correction before transmit –Examples: TCP, UDP, SPX Network –Provide logical addressing which routers use for path determination –Examples: IP, IPX

NSH0503/01/ Data link –Combines bits into bytes and bytes into frames –Access to media using MAC address –Error detection not correction –Examples: 802.3/802.2 Physical –Moves bits between devices –Specifies voltage, wire speed, and pinout cables –Examples: EIA/TIA-232, V.35 The Data-Flow Layers

NSH0503/01/ Peer-to-Peer Communication For data to travel from the source to the destination, each layer of the OSI model at the source must communicate with its peer layer at the destination. During this process, the protocols of each layer exchange information, called protocol data units (PDUs), between peer layers. Each layer of communication on the source computer communicates with a layer-specific PDU, and with its peer layer on the destination computer.

NSH0503/01/ The TCP/IP Reference Model

NSH0503/01/ TCP/IP Protocol Graph

NSH0503/01/ Applications FTP – File Transfer Protocol HTTP– Hypertext Transfer Protocol SMTP – Simple Mail Transfer Protocol DNS – Domain Name System TFTP– Trivial File Transfer Protocol

NSH0503/01/ OSI Model and TCP/IP Model

NSH0503/01/ Use of the OSI Model

NSH0503/01/ Names for Data at Each Layer

NSH0503/01/ De-Encapsulation When the data link layer receives the frame, it does the following: –It reads the physical address and other control information provided by the directly connected peer data link layer. –It strips the control information from the frame, thereby creating a datagram. –It passes the datagram up to the next layer, following the instructions that appeared in the control portion of the frame.