COMPUTER NETWORKING By: Dr. Noor Dayana Abd Halim
COMPUTER
NETWORKING
By: Dr. Noor Dayana Abd Halim
Defining Computer Network
Computer network is a collection of computers and
other hardware devices so that network users can
share hardware, software, data and they can
communicate with each other electronically.
Defining Computer Network
Computer networking is connecting a computer with
other computers or other devices to enable them to
communicate with each other, between
– computer devices/equipments
– transmission media to send/control data/signals
– communication devices to transmit/send data from
sources to destinations
– softwares
Type of Network
Many types of network depending on the
geographical area.
Type of Network
Type of Network : Local Area Network, LAN
Covers relatively small geographical area. Eg.
Home, schools, office building
Client/ server network is example of LAN
Allows file exchange, emails, printer sharing or
accessing the internet
Type of Network : Metropolitan Area Network, MAN
Network designed to service a metropolitan area, a
city or a county
Owned or provided by a city or network provider
For local people‟s access to internet
Example in Malaysia? 3 network of LAN for Mid
Valley City
Type of Network : Wide Area Network, WAN
network that covers large / broad geographical area
Ex: telecommunications network that links across
metropolitan, regional, or national boundaries) using
private or public network transports.
In essence, this mode of telecommunication allows a
business to effectively carry out its daily function
regardless of location.
Internet: world‟s largest WAN
Type of Network : Wide Area Network, WAN
Network Component
What you need to set up a network?
1. Hots / End Nodes
2. Transmission Media
3. Network Electronics Devices
4. Software / Application
5 Network Architecture Standards & Protocols
Network Component : 1. Hots /End Nodes
Refers to the data source and the data destination.
Examples:
– Personal computers
– Terminals
– Workstations
– Automatic Teller Machine
Network Component : 2. Transmission Media
For transmitting data and control signals
Responsible for sending electric or signal through
spesific media. It can be bounded (wired) or
unbounded (wireless) media
Network Component : 3. Network Electronic Device
Responsible to control data from source to destination
Provide interface between different media transmitter or for different protocol
• To connect multiple network together or to connect computer or network to the internet
•Examples:
– Bridges
– Routers
– Multiplexers
– Switches
– Hubs
– Gateways
– Front End Processors
Network Component : 3. Network Electronic Device
Network Component : 4. Applications/ Software
The applications at the end nodes (what is end
node?) normally involves technique and protocols
The protocol determines the rules and procedure to
send data, terminate data, interpret data, present
data and control mistakes
Software in the network functions to ensure data is
delivered at respective destination
to control data transmission
Network Component : 5. Network Architecture
Standard & Protocol
NAS: The blueprint of standards that define:
– How device in a network typically connect
– How the device can communicate
To ensure interoperability between various devices
and equipment made by different vendors.
To enable devices made by different companies to
work or communicate with each other.
Network Component : 5. Network Architecture
Standard & Protocol
Example : TCP/IP, Ethernet (802.3), Wi-Fi (802.11),
WiMAX etc
Networking Architecture
Network architecture is the way they are design to
communicate
2 types :
1. Client/Server Networks
2. Peer to Peer Networks
Networking Architecture : 1. Client/Server
Networks
1) Client/ server:
Client = computers that request or utilize network
resources
Server = processing the request by client
What is network server? Provide access to software,
files etc being shared in the network
Retrieves file from server: download
Transfer from client to server : upload
Networking Architecture : 2. Peer to Peer
Networks
2) Peer to peer
No central server
Have direct access to other devices attached to the
network
As long as they are declared as „shared devices‟
Internet peer to peer: eg. iTunes, Bluetooth between
handphone
Network Topology
Network topology is the study of the arrangement
or mapping of the elements (links, nodes, etc.) of a
network, especially the physical (real) and logical
(virtual) interconnections between nodes
How the hardware/ devices are placed and
arranged
2 types
1. Physical
2. Logical
Network Topology: 1. Physical
1. Physical topology :
• The physical layout of devices on a network. or the way that the devices on a network are arranged and how they communicate with each other
• The way that the workstations are connected to the network through the actual cables that transmit data
• 5 Types :
1. Linear Bus
2. Ring / Star-wired
3. Star
4. Tree / Hybrid
5. Mesh
Physical Network Topology: 1. Linear Bus
1. Linear Bus
consists of central cable to which all devices are connected with a terminator at each end. ƒ
All nodes (file server, workstations, and peripherals) are connected to the linear cable.
Data transmitted through the bus line from one device to the other.
Network cannot function when the bus line fails.
Ethernet and LocalTalk networks use a linear bus topology.
The message is transmitted along the cable and is visible to all computers connected to that cable.
Physical Network Topology: 1. Linear Bus
Physical Network Topology: 2. Ring
2. Ring
• Each of the systems is connected to its respective neighbor forming a ring.
• Sometimes called “star-wired network”
• The main difference between the bus and ring is that the ring topology does not require termination. Because the systems are connected all together in a loop, there is no beginning and end point as there is with the bus topology.
• No terminator and no bounce back signal.
Physical Network Topology: 2. Ring
Physical Network Topology: 3. Star
3. Star
• All networked devices are connected directly to the central
device (hub) / concentrator
• From central device, all network transmissions are sent
• Data on a star network passes through the hub or concentrator
before continuing to it destination. The hub or concentrator
manages and controls all functions of the network. It also acts
as a repeater for the data flow.
Physical Network Topology: 3. Star
Physical Network Topology: 4. Tree / Hybrid
4. A tree (hybrid)
• Can incorporate structures such as ring, star and bus network in
one large network
• It consists of groups of star-configured workstations connected
to a linear bus backbone cable.
• Allow for the expansion of an existing network, and enable
schools to configure a network to meet their needs.
Physical Network Topology: 4. Tree / Hybrid
Physical Network Topology: 5. Mesh
5. Mesh
• Computers have redundant physical connections to one
another
• When the mesh network is a WAN (such as the
Internet), or a LAN that is divided into multiple
subnets, routers make decisions about which of the
multiple available paths will be taken.
• Decide based on which one is the most „effective‟
Network Topology: 2. Logical
2. Logical topology :
• how the systems communicate across the physical topologies
• the way that the signals act on the network media, or the way that the data passes through the network from one device to the next without regard to the physical interconnection of the devices.
• 2 types:
1. shared media topology
2. token-based topology
Logical Network Topology: 1. Shared Media
1. Shared media
• In a shared media topology, all the systems have the ability to access the physical layout whenever they need it.
• Advantage : the systems have unrestricted access to the physical media.
• Disadvantage : Collisions - If two systems send information out on the wire at the same time, the packets collide and kill both packets. If add more systems to the network, there is a greater opportunity for collisions.
• To help reduce the number of collisions, many networks are broken up into several smaller networks with the use of switches or hubs, and each network is then referred to as its own collision
•Example: Ethernet
Logical Network Topology: 2. Token Based
2. Token-Based
• Have a token that travels around the network.
• When a system needs to send out packets, it grabs the token off of the wire, attaches it to the packets that are sent, and sends it back out on the wire.
• As the token travels around the network, each system examines the token.
• When the packets arrive at the destination systems, those systems copy the information off of the wire and the token continues its journey until it gets back to the sender.
• When the sender receives the token back, it pulls the token off of the wire and sends out a new empty token to be used by the next machine.
Logical Network Topology: 2. Token Based
Advantage : Do not have the same collision problems that Ethernet-based networks do because of the need to have possession of the token to communicate.
• Disadvantage : Latency – Because each machine has to wait until it can use the token, there is often a delay in when communications actually occur.
• Token-based network are typically configured in physical ring topology because the token needs to be delivered back to the originating machine for it to release.
• The ring topology best facilitates this requirement.
Thank You!