NETWORKINGDEPARTMENT OF INFORMATION SYSTEMSCOLLEGE OF COMPUTER STUDIESXAVIER UNIVERSITY – ATENEO DE CAGAYAN

Data Communications and Networking

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What is a Network?• Defined as two or more computing devices connected

together in such a way that they can share resources• Resources:• files• folders• printers• disk drives• etc.

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What is a Network?• A collection of computers or other hardware devices that are

connected together, either physically or logically, using special hardware and software, to allow them to exchange information and cooperate

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What is Networking?• Term that describes the process involved in designing,

implementing, upgrading, managing, and otherwise working with networks and network technologies

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Advantages of Networking• Connectivity and Communication

• Data Sharing

• Hardware Sharing

• Internet Access

• Internet Access Sharing

• Data Security and Management

• Performance Enhancement and Balancing

• Entertainment

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Disadvantages of Networking• Cost of setup

• Management and administration costs

• Undesirable sharing

• Illegal or undesirable behavior

• Data security concerns

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Basic Components of a Network• Server

• core component of the network• provides link to the resources necessary to perform any task

• Client• requests and receives information over the network client• depends primarily on central server for processing activities

• Circuit• cables, ports and other devices that connect the server and the client

computers

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Network Interface Card (NIC)• Circuit board that fits in one of the computer’s internal expansion

slots

• Contains circuitry that handles sending, receiving, and error checking of transmitted data

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Key Points in Networking• Important characteristics that influence transmission technologies

and communication protocols• size• shape

• Networks are classified according to area over which they extend

• Size and extension depend on number of nodes that need to communicate, and where these nodes are in relation to each other

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Network Classifications• PAN (personal area

network)• refer to the

interconnection of personal digital devices or consumer electronics w/n the range of 30ft (10m) and without the use of wires or cables

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Network Classifications• LAN (local area network)

• data communications network the connects personal computers within a very limited geographical area

• school computer labs• home networks

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Network Classifications• MAN (metropolitan

area network)• public high-speed

network capable of voice and data transmission within the range of 50mi (80km)

• ISPs• small cable TV

companies• local telephone

companies

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Network Classifications• WAN (wide area

network)• covers large

geographical area and usually consists of smaller networks

• nationwide banks• large cable TV

companies• multi-location

superstores• internet

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Network Topologies• Architectural “drawings” to show the overall physical configuration

for a given communications system

• Indicates the access methods and governs the rules that are used to design and implement the communication system

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Network Topologies• Bus topology

• Single electrical circuit to which all devices in network are connected

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Network Topologies• Star topology

• individual computers are connected to a central device such as a hub or a switch

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Network Topologies• Ring topology

• a collection of separate point-to-point links arranged to make a ring

• each nodes NIC has one input and one output connection

• so each node has two links

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Communications Model

Source

Transmitter Receiver

Destination

Source System

Destination System

Transmission System

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Communications Model

Personal Computer

ModemBroadband Connection

Modem

Server

NETWORK TOPOLOGY CASE STUDY:

This will serve as your ACTIVITY 2.

SEARCH FOR ONE (1) CASE STUDY IN EITHER OF THE FOLLOWING TOPOLOGY ARE PRESENT:

* BUS TOPOLOGY * STAR TOPOLOGY * RING TOPOLOGY

Take note what are the advantages and disadvantages of your chosen topology based on your case study. Put it in Word, then save as “<Lastname>_Activity2”

Be ready! I will call some students to present their research

Network Building BlocksCOLLEGE OF COMPUTER STUDIESXAVIER UNIVERSITY – ATENEO DE CAGAYAN

Network Devices• Sometimes referred to as a network appliance

• Any electronic device that broadcasts network data, boosts signals, or routes data to its destination

Network Devices• Node

• Each connection point on a network• Usually contains:

• Computer• Networked peripheral• Network device

• Workstation• Personal computer connected to a network

Network Devices• Network Interface Card (NIC)

• Circuitry to connect to LAN• Sometimes built-in in some personal computers• Can be added to an expansion slot or USB port

• Networked peripheral• Any device that contains network circuitry to directly connect to a network• Examples: printers, scanners, storage devices

Network Devices• Router

• Central distribution point for getting data to its destination

Network Devices• Hubs

• Extends a wired network by adding additional ports

Network Devices• Switches

• Intelligently facilitates communication among multiple devices on a network

Network Devices• Gateways

• Joins two different types of networks, such as your home network and the Internet

Network Devices• Bridges

• Connects two similar networks

Network Devices• Wireless access points

• Allows wireless devices to connect to a wired network

Network Devices• Repeaters

• Extends the range of a network by restoring signals to maximum strength and retransmitting them

Sample LAN Setup

Network Links• Links

• Communications channel• Physical path or a frequency for signal transmissions

• Wired – cables• Cat 5 or Cat 6 (max length of 100m)• RJ45 connector

Network Links• Bandwidth

• Transmission capacity of communications channel• High-bandwidth (broadband) can carry more data than low-bandwidth

(narrowband)• Digital bandwidth is measured in bits per second (bps)• Analog bandwidth is measured in hertz (Hz)

Communications Protocol• Protocol

• Set of rules for interacting and negotiating

• Communications protocol• Set of rules for efficiently transmitting data from one network node to

another

• TCP/IP• Transmission Control Protocol/Internet Protocol• Internet data support and standards for LANs

Communications Protocol• Aspects of network communications that communications protocol

handles• Dividing messages into packets• Affixing addresses to packets• Initiating transmission• Regulating flow of data• Checking for transmissions errors• Acknowledging receipt of transmitted data

Communications Protocol• Packets

• A parcel of data that is sent across a computer network• Contains:

• Address of sender• Destination address• Sequence number• Some data

Communications Protocol• Data are broken down into packets and reassembled in the destination

according to sequence number

Communications Protocol• Circuit switching

• Used by some technologies like telephone system• Dedicated private link between one telephone to another telephone for the

duration of the call• Inefficient

Communications Protocol• Packet switching

• Divides message into several packets that can be routed independently to their destination

• Messages divided into equal-size packets are easier to handle than an assortment of small, medium, large, and huge files

• Packets are shipped over the circuit on a first-come, first-served basis

Communications Protocol

Communications Protocol

Communications Protocol• Routing of packets

• Each packet contains the address of the destination device• Communications protocol specify the proper format of addresses• Two commonly used addresses:

• MAC address• IP address

Communications Protocol• MAC address

• Media Access Control address• Unique number assigned to a network interface card when it is

manufactured• Used in low-level network functions and can also be employed to establish

network security

Communications Protocol• IP address

• Internet Protocol address• Series of numbers used to identify a network device (computers, servers,

peripherals, and devices)• Originally used in the internet but used in LANs• Example: 204.127.129.1

• Four groups of numbers separated by period• Octet (eight bits in binary)

Communications Protocol• IP address

• Assigned by ISPs or system managers• Sometimes assigned by DHCP

• Dynamic Host Configuration Protocol• Automatically distributes IP addresses• Computers send a query to the network device acting as the DHCP server• IP address is good for that session only