Computer Networks

Computer Networks BTT 101 / 2O1 Lesson 10 Dundas Valley Secondary Mr. Young

Connecting to the Internet • To connect to the Internet from home you need WAN Link Ethernet Cable A Computer PC Laptop iPhone etc A Modem DSL Cable An ISP

Connecting to Your ISP • An Internet Service Provider is a company that offers its customers access to the Internet through their own LAN. Customers connect to the ISP through a modem such as DSL, dial-up or cable . • A Modemis a device that converts (modulate and demodulate) the Ethernet signal from your computer into the DSL or cable signal.

Ethernet TechnologyThe Wired Network • Ethernetis a technology for wired networks. • Plug a Patch cable (or Ethernet cable) into the Ethernet NIC (Network Interface Card) on your computer and into the modem Network Card Ethernet Cable

Ethernet Technology • In networking, a protocol is a set of rules that govern communication. • Ethernet is a protocol that defines the cabling and how the signals are sent. • Gigabit Ethernet is the newest version with a bandwidth of about 1 Gbps. A patch cable plugs into an RJ45 plug on the network card

The Home Network • If you have more than one computer that needs to be connected to the Internet, then you need a network device called a router. The router plugs into a modem, which linksto the ISP Each computer connects to the router with a patch cable

The Router • A router is a network device that forwards packets from one network (LAN) to another using IP addresses. • A LAN or Local Area Network is a type of computer network covering a small physical area, like a home, office, or small group of buildings, such as a school. • Ethernet and WiFi are two common technologies for connecting computers in a LAN.

The LAN The computersin each LANplug into a network switch. The switch concentrates network connections. This means that it brings network cables together at a central point. Three LANs connected to a routerand then to the Internet

WiFi • Home networks also use wireless technology or WiFi • The wireless version of Ethernet. WiFi stands for “Wireless Fidelity” imitating Hi-Fi for “high fidelity" audio. • The official standard is called IEEE 802.11 with improvements marked by letters • 802.11g is called Wireless-G • 802.11n is called Wireless-N

Wireless Networks at Home • In your home network, you can have both wired (Ethernet ) and wireless (WiFi) devices • Most desktop computers have an Ethernet card (NIC) • Most laptops and netbooks have a wireless network card (and some also have Ethernet) One type of wireless network card looks like a USB flash drive but it just connects the computerto a wireless network.

Wireless Routers • Some routers have both Ethernet and WiFi WiFi antennae WAN port 4-port switch A Linksys wireless router

Network Communication • Information like email and Webpages travel through your home network (a LAN) and over the Internet in packets. • A packet is like an electronic envelope that contains your data. Packets that are sent over the Internet are usually about 1500 bytes . It takes many packets to send the average message.

Network Communication • The packet contains the IP Address of both the destination and the source (the “mailing address” and the “return address” on a letter). Source Address  your address Destination Address  where it is going

Internet Protocol • An Internet Protocol or IP Address is the address of a computer on a network. • It is a 32-bit binary number. • It is written in decimal numbers to make it easy to read and write. • It has 4 numbers between 0 and 255 separated by dots. • For example: 192.168.1.202 • Binary: 11000000101010000000000111001010

Your IP Address • Every computer on a TCP/IP network must have an IP address • TCP/IPis the name for the suite (group) of protocols that govern the Internet • HTTP is one protocol in the TCP/IP suite • HTTP is a protocol that governs Webpages • Many computers get an IP address automatically from a DHCP server • At home your router “serves” IP addresses to computers on the LAN

DHCP • Dynamic Host Configuration Protocol • A networking protocol used by computers on a network to get an IP Address. • The computer (a DHCP host) sends a request over the LAN for an IP Address. • A DHCP server (a router or server) assigns a temporary and unique IP Address to the host. • This is called a Dynamic IP Address. • If the user configures the IP Address themselves, this is called a Static IP Address.

WAN • When several LANs are linked togetherthis is called a Wide Area Network or WAN • The Internet is a planet wide WAN.

Internet Backbone The network backbone is the part of a network that connects the core points in a WAN. It usually has the highest-speed transmission paths in the network and may also run the longest distances. Smaller networks are attached to the backbone.

Bandwidth • Bandwidth is the amount of data sent over a communication line, like a network cable. • It is measured in bits per second or bps. • A signal sent over an Ethernet cable, for example, has a bandwidth of 100 Mbps (megabits per second). • Gigabit Ethernet is 1000 Mbps or 1 Gbps

Bandwidth • Bandwidth is easier to understand if you compare it to water flowing through pipes. • With a bigger pipe more water canflow per minute. • In electronic communication, the wires are not bigger but use different technologyto send data fasteracross different data “pipelines” or channels. With a bigger “pipeline” more data can flow

The Internet

Computer Networks