Network and internet Basics

Network and internet Basics Lecture9 Computer skills2 2018-2019 1. Identify communications networks in daily life 2. Distinguish between types of networks 3. Identify common types of network hardware

1. Identify communications networks Communication Systems Networking is everywhere, and many of our everyday activities are enabled or assisted by computer networking, even the activities that might not on the surface seem to have anything to do with it. Example When you call your mother on your cell phone on the way home to tell her about your purchase, your call goes through the wireless network for your cell phone provider.

The Internet Internet A global packet-switched network created cooperatively by multiple companies, governments, organizations. protocol A rule or custom that governs how something is done. In a computer context, it refers to a standard for transferring data. Internet service provider (ISP) A company that maintains a direct connection to the Internet and leases access to it to individuals and companies. protocol stack A related group of protocols for example, TCP/IP. TCP/IP The protocol suite (set of rules) that defines how data will move on the Internet and on most other modern networks. and standards

Private Digital Networks Using the Internet is also not very secure; it s an open system, and data being sent and received can easily be snooped. To tighten the security when using the Internet as a conduit, many companies use a software technology called virtual private networking (VPN).

virtual private networking (VPN) A method of creating a secure, private communication tunnel using a public communications channel such as the Internet.

Satellite Data Networks satellite geosynchronous orbit with the Earth, more than 22,000 miles up. A satellite contains transponders, which are two- way radios that communicate with stations on the ground. Satellites are used to quickly send information between two points on Earth that are physically separated by a great distance. A data transmitter/receiver in

examples, When the Olympics are held in one country, satellites are used to broadcast the video of each competition nearly instantly to every other country. Satellites are also used for services like satellite radio (Sirius/XM, for example) and satellite TV broadcasts such as DirecTV and Dish Network Some Internet services also use satellites to provide Internet access to areas where other high-speed connection technologies are not available.

Cell Phone Networks Cellular telephone companies have their own data networks, using a combination of satellites, cables, and on-ground towers with transmitters and receivers on them. Calls connect to the cell tower that is closest to the phone s current location, and that cell tower then taps into the larger telecommunications network via satellites and cables.

smartphone A cellular phone that includes computer applications and Internet access capability. tether To connect a smartphone to a computer so that the computer can use the smartphone s Internet access.

2. Types of networks One way to classify networks is according to the geographical range that they cover, from a few feet within a single person s office to a huge area that covers multiple countries or even multiple continents. 1. Personal Area Networks 2. Local Area Networks 3. Metropolitan Area Networks 4. Wide Area Networks

Personal Area Networks A personal area network (PAN) consists of devices that directly connect to a single computer. examples, if you are showing a presentation in a conference room during a business meeting, you might connect your notebook PC to the projector in the room. You might also form a PAN by connecting your smartphone to your computer.

Local Area Networks A local area network (LAN) is a network in which all the devices are located within the same physical location, such as a single building or a group of adjacent buildings. A key characteristic of a LAN is that it is contained within a relatively small area. example, your home networkis a LAN, and so is the network at your school.

Metropolitan Area Networks A metropolitan area network (MAN) is a network that spans an entire town or city, a metropolitan area that might span a major city and its suburbs. A city might invest in a network infrastructure, example, and then businesses and individuals within that area might sign up to use the network.

Wide Area Networks A wide area network (WAN) is a geographically dispersed network, usually consisting of at least two LANs connected together by an external link. Example A business or college with multiple separate campuses might link all the individual LANs together to form a WAN. A WAN is not necessarily managed by a single organization and may include architecture and communications hardware from several different service providers.

3 .Network topology Network topology defines the structure of the network. Physical topology, which is the actual layout of the wire or media. Logical topology, which defines how the media is accessed by the hosts for sending data. The logical topology of a network is how the hosts communicate across the medium. The two most common types of logical topologies are broadcast and token passing.

Physical topology

Physical topology Bus Uses a single backbone cable All hosts connect directly to backbone

Ring Topology Connects each host to the next, and the last to the first Physical ring of cable

Star Connects all cables to a central point of concentration Usually a hub or switch at center

Extended Star Links stars by linking hubs or switches

Hierarchical Similar to extended star Links star LANs to a computer that controls network traffic Mesh Each host is connected to all other hosts No breaks, ever!

Logical Topologies Broadcast topology means that each host sends its data to all other hosts on the network medium. There is no order that the stations must follow to use the network. It is first come, first serve. Ethernet works this way as will be explained later in the course. Token passing controls network access by passing an electronic token sequentially to each host. Two examples of networks that use token passing are Token Ring and Fiber Distributed Data Interface (FDDI).

4. Network Hardware Network connectivity requires both hardware and software. The software portion is handled by the operating system; all modern operating systems include network support Network Adapters 1. Switches and Hubs 2. Routers 3. Gateways, Bridges, and Repeaters 4. Network Cables

network adapter A hardware component that enables a computer to connect to a network. network interface card (NIC) A network adapter that is on an expansion card, rather than built into the computer s motherboard. Sometimes used informally to refer to any network adapter.

Switches and Hubs switch A gathering point for the computers in a LAN to connect with to participate in the network, box that provides a central gathering point for all the computers in an Ethernet LAN. wireless access point (WAP) A wireless switch. hub A primitive version of a switch that lacks the capability to read packet addresses and route them to the appropriate port.

Routers A router performs all the same functions as a switch, but it also has an added bonus: It can direct traffic into and out of the LAN. example, suppose you have two separate groups of computers, each group connected to its own switch, and you want their computers to be able to communicate with one another.

Gateways, Bridges, and Repeaters gateway is a connector box that enables you to connect two dissimilar networks by translating the data requests between them and providing the correct physical connectors for each network type. example, a gateway might join an Ethernet-based LAN to a mainframe computer. A bridge is a device that connects two similar networks, such as Ethernet networks in two different buildings.

Network Cables twisted-pair cable: Cable that transfers data via pairs of copper wires that are twisted around each other to reduce electromagnetic interference. electromagnetic interference (EMI) The corruption of data as it is passing through a cable due to the magnetic field generated by a nearby cable. unshielded twisted pair (UTP) A type of twisted-pair cable that does not have an outer sheath that protects against external EMI. shielded twisted pair (STP) A type of twisted-pair cable that has an outer sheath that protects against external EMI.