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Chapter 8 ITE 1 Basic Networking Networking Basics • Two Basic Types of Connections Are: • WAN • Wide Area Network • Think Modem - Long distances • LAN • Local Area Network • Think This Room Connection Media • Copper Cabling • Coax or UTP • UTP is limited to 100 meters • Fiber • Uses glass strands to carry pulses of light • No electrical issues - Longer Distances • Wireless • Radio signals or infrared Connection Media • UTP Cabling • Unshielded Twisted Pair • Uses Copper Wire • Number of twists and number of conductors determine category number (Cat 3, Cat 5, Cat 6 etc.) Oddball WAN Media • Power lines (PLC) can be used to carry both voice and data. • It can actually provide higher bandwidth than phone lines (PSTN) Why Network? • Share files and resources • Lower Cost Software Licensing • Central Administration WLAN • Are wireless LAN’s • Can cover small or large areas. • Small area connections use shared bandwidth. Network Types • There are two basic types of networks • Peer to Peer • All machines are equal • No central administration • Client/Server Networks • Centrally administered • Lots of control and security, but increased overhead • Easy data backup and centralized access to data Bandwidth • Network speed is measured in Bandwidth • Bps - Bits per second • Kbps - Kilobits per second • Mbps - Megabits per second Communication Direction • Simplex • One way transmission • Think Radio Station • Half-Duplex • One Direction at a time • Think Walkie Talkie • Full-Duplex • Both directions at once • Think telephone Network Addressing • Broken into three classes • Class A: • 1st Octet is a Network Address • Class B: • 1st and 2nd Octets are Network Addresses • Class C: • 1st, 2nd and 3rd Octets are used to identify the network address Network Addressing • The remaining addresses are used for individual devices on each type of network. Network Addressing • Addressing can be done by the administrator and manually added to each machine or • Done automatically through a process called DHCP where the address are handed out on a temporary basis Network Addressing • Network Addressing has 3 Parts • IP Address - Must be unique for every machine on the network • Subnet Mask - Should be the same for every machine on the network • Tells the network which part of the IP is for the network address and which part is for the individual devices • Gateway - Tells the machine where to send the packets that go to the internet • Machines can communicate locally without the proper gateway address. Protocols • Protocols are a set of rules that govern communications • See page 8.3.4 for a list of common protocols ICMP • Internet Control Message Protocol is used to send messages between devices regarding network conditions • One type of ICMP is called Packet Internet Groper or PING • It is used to test end to end connectivity between devices • Tracert shows the whole route the packets took along with timing. How Information is Sent • Files are broken down into segments. • The segments get headers and trailers added for addressing and error checking. • This process is called Encapsulation. Network Devices • Hubs • Hubs are “Dumb Devices” They are really multi-port repeaters. • They simply send anything they receive in any one port out all of their other ports. • They run at Half-Duplex only. • They extend the network without breaking it into segments as switches and routers do. Network Devices • Routers • Routers make forwarding decisions based upon programming. • They are very smart devices and can dynamically reroute packets as network conditions change. Network Devices • Switches • Switches and Bridges (Bridges are single-port switches) are smarter than hubs. • They make forwarding decisions based upon Mac (Hardware) Addresses • They are good because they block unwanted traffic. Network Topographies • Ethernet Standard (IEEE 802.3) systems use a Star physical topology • But their logical topology is actually a bus topology • There are other types including a Mesh Topology where everything is connected to everything else and a Ring Topology which is just as it sounds. Ethernet Standards • Wireless Standard can be found on page 8.7.2 • One of the most common is 802.11g which runs at speeds up to 54 mps. How LAN’s Work • To avoid collisions where multiple devices try to talk at once: • Ethernet uses CSMA/CD • When a collision occurs all devices back of a random amount of time, then listen to see if the coast is clear before resending Models • There are two models for explaining how Networking is done. • One is TCP/IP • The other is the OSI Model • See pages 8.8.3 for an explanation of the different models and how they relate to each other. OSI Model • Explains how things work. • Makes it so equipment and software from different sources will work together. OSI Model • Data link layer controls physical addressing otherwise known as the MAC address. VoIP • What is VoIP? • It’s voice (As in Telephone) over a computer network. (Voice Over IP) • Advantage: It’s very cheap. Think Vonage • Disadvantage: If your internet goes down so does your phone service. Other Odd Ways of Connecting • PLC • Carries Voice and Data Across Power Lines • Requires no control wiring for electrical devices at the customer’s end. • Actually has more bandwidth than most other WAN technologies Other Ways To Connect • ADSL • Uses existing phone lines • Faster download (Downstream) speeds than up upload (Upstream) speeds. • Limited distance from the phone company switching center. Other Ways to Connect • ISDN • Uses 2 phone lines - 3 Channels, 2B and one D. • Faster than dialup, but slower than cable or DSL. • Expensive • Called BRI • Not used much anymore. That’s It! • Good luck on the test!