ITED 328 Lecture 4 12 Feb 2004

Loosely covering Chapter 5 Internet and LAN Technology

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Section 1 - Networks

A quick over view of networking in general.

A network is a combination of computer, cables, NICs, and software.

Each connection is called a "Node".

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Reasons to use a network:

Share files.

Transfer files.

Access information and files.

Use of an application by multiple users.

Share printers ( or other resources).

Use electronic mail (email).

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NETWORK DEVICES:

Network file server ( or servers).Network host computers.Individual workstations.HubsRouters Gateways BridgeRepeatersTransmission media.

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More on devices:

Hub- device that connects computers together.Routers connect two broadcast networks (at layer 3 the Network layer).Gateways connect multiple computers so they can access the network it at the same time. Connects networks that use different protocols( at layer 7, the gateway layer).Bridges connect LANS at the data link layer.Transmission media: fiber optic, coaxial, twisted pair, also air.

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Network configurations (a.k.a. topology)

STARRINGBusPeer to Peer

(how we are going to do our next lab !)

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Network Protocols

A method of coordinating communications on a network. Different types Low Level PROTOCOLS - no guarantee

data is received. Mid level PROTOCOLS – Limited control Higher level PROTOCOLS User has

control.

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LOW LEVEL PROTOCOLS

Token Ring is a Local Area Network (LAN) protocol. The Token Ring protocol was first developed by IBM. Token Ring is standardized in IEEE 802.5 that was published in 1985. The protocol deals with the problem of collision, which is defined as a state were two stations transmit at the same time. In order to avoid the situation of collision there was a need to control the access to the network. This kind of control is possible by the use of a control (permission) called token. The token is passed from one station to another according to a set of rules.

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Token Ring continued…………..

Only the station in possession of the token is allowed to transmit data. Each station repeats the data, checks for errors, and copies the data if appropriate. When the data is returned to the sending station, it removes it from the ring. The token Ring protocol supports priorities in transmission.

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Token Ring continued…………..

2 ways to implement: Star or Ring

Source http://www2.rad.com/networks/1996/toknring/toknring.htm#Topology

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Ethernet

Ethernet is communication over a single cable shared by all devices on the network. Once a device attached to this cable, it had the ability to communicate with any other attached device. This allows the network to expand to accommodate new devices without requiring any modification to those devices already on the network.

Source http://computer.howstuffworks.com/ethernet2.htm

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FDDI

Fiber Distributed Data Interface

Used to connect two or more LANs over long distances ( i.e. transcontential).

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MID LEVEL PROTOCOLS

Initiate communications, send and receive data, can terminate communications.NetBIOS, TCP/IP

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High Level Protocols

Client /ServerUnix / Linux LANSTCP/IPtelnetftprlogin, rcp,rsh, pingNFS - Network Files System

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Software used for networks

Novell, Windows NT Advanced Server

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The Seven layers of the OSI

7 Application 6 Presentation5 Session4 Transport3 Network 2 Data link layer (sub layers Logical Link and MAC)

1 Physical (hardware layer)

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Misc Info

How the data is sent: Frames and Packets!

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THE INTERNET

IP address 32 bit host address of a computer on the networkClass A - high bit 0, 7-bit network number, 24-bit host number. n1.a.a.a 0 <= n1 <= 127

Class B - high 2 bits 10, 14-bit network number, 16-bit host number. n1.n2.a.a 128 <= n1 <= 191

Class C - high 3 bits 110, 21-bit network number, 8-bit host number. n1.n2.n3.a 192 <= n1 <= 223

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IP Addresses

Dynamic or static IP Address

IP Address

network host subnet

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More Misc Info ……

Domain name or fully qualified domain name is a way for all the computer in the world to have a unique name on the internet. ( STARTED by DARPA)

Different domains: *.com *.edu, *.gov, *.net , *.org , *.mil, *.info , *.biz , *.int

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How to be connected:

DIAL UP via phone and modemDSL - Digital Subscriber LineDSS - Direct Satellite ServiceWirelessBroad band - covers frequencies from audio to video

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Standards to Know of: IEEE 802.11

IEEE 802.11 has many subsections:802.11 a is for radio-based LAN protocol which speaks OFDM at 5GHz, one of the two wi-fi protocols. 802.11b is wireless local area networks (WLAN) standard protocol which speaks DSSS at 2.4GHz. 802.11b is one of the two wi-fi protocols. It operates at 11 megabits per second (Mbps).

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802.11 Continued ……

An IEEE wireless local area network (WLAN) standard protocol, expected to be approved in June 2003. 802.11g offers wireless transmission over relatively short distances at up to 54 megabits per second (Mbps).