Staffsite STMIK PPKIA Pradnya Paramita 5f0c8 modul 02

Module 2:
Understanding Local
1.5 Understand network topologies and access
methods
Area Networks

Agenda
1

Network Topologies

2

Ethernet Standards

3

Peer to Peer vs. Client/Server
Models

Network

Topologies

What is a network topology?
A network topology defines the physical connections of
hosts in a network
• There are multiple types of topologies, including:


• Bus
• Star
• Ring
• Mesh

Bus Topology
All devices are connected via
copper cable in a line

Star Topology



Each host is connected to a
central connecting device
with twisted-pair cabling
• The central connecting device can be a

hub, a switch, or a SOHO router

This is the most commonly
used topology
• NOTE: two star topologies
can be connected via their
central connecting devices to
form a star-bus topology


Ring Topology
Each device is connected to the
LAN using a closed loop
• NOTE: Each device is connected to two


other devices

Mesh Topology
Each computer connects to
every other computer in a
LAN
• No central connecting device
• Setup is fault-tolerant


• allows data to be sent via multiple

pathways if one path fails

Ethernet
Standards

What is Ethernet?
A standard that defines how data is sent and received between
devices

• Most widely used standard on the Internet today


• Token Ring and FDDI are used when Ethernet is not



Standardized by the Institute of Electrical and Electronics
Engineers (IEEE) as 802.3

What are frames?
Devices on Ethernet networks
transmit frames
• Sequence of bits containing a detectable

beginning and end of a packet in the
stream of bits
• Include physical address information that
helps switches determine where to send
data

beginning

address
info

dat
a

end

IEEE 802.3
802.3 Version

Data Transfer Rate

Cable Standard

Cabling Used

802.3


10 Mbps

10BASE5

Thick coaxial

802.3a

10 Mbps

10BASE2

Thin coaxial

802.3i

10 Mbps

10BASE-T


Twisted pair (TP)

802.3j

10 Mbps

10BASE-F

Fiber optic

802.3u

100 Mbps

10BASE-TX
100BASE-T4
100BASE-FX

TP using 2 pairs

TP using 4 pairs
Fiber optic

802.3ab

1000 Mbps or
1 Gbps

1000BASE-T

Twisted pair

802.3z

1000 Mbps or
1 Gbps

1000BASE-X

Fiber optic


802.3ae

10 Gbps

10GBASE-SR, 10GBASE-LR,
10GBASE-ER, and so on

Fiber optic

802.3an

10 Gbps

10GBASE-T

Twisted pair

IEEE 802.3



Defines carrier sense multiple access with collision
detection (CSMA/CD)
• Devices share a connection
• If they send data at the same time, collisions occur
• So, only one computer can transmit at a time



CSMA/CD allows devices to send/receive data by limiting
collisions

CSMA/CD Process
1. Assemble a frame
2. Check if the medium is free
a.
b.

If free, transmit a bit of the frame
If not, don’t transmit and repeat step 2


3. Check if a collision was detected
a.
b.

If so, implement the collision detected procedure
If not, transmit the remaining bits in the frame

What is the collision detected
procedure?
If a collision is detected, then a network adapter will perform the
following steps:
1. Send out a jam signal to stop all communication on the
medium
2. Wait based on the number of collisions detected
3. Starts sending the remaining bits of the frame

Peer to Peer vs.
Client/Server
Models

The Client/Server Model
Servers are computers
dedicated to providing
specific types of services or
data
• A client (a computer) uses
software to ask a server for
data or services
• The server provides the data
or service to the client


Hey! Can you
please send
me an HTML
file?

Client
Server

Types of Servers
SERVER TYPE

FUNCTION(S)

File server

Store files, software, or data for access by
computers on a network.

Print server

Allows computers that are connected to a network
to control printers on the network.

Database
server

Houses a relational database made up of multiple
files.

Network
controller

Controls accounts that are domain, as well as the
devices that belong to a network.

Messaging
server

Provide services related to email, fax, instant
messaging and collaboration.

Web server

Provides access to HTML documents for
computers on a network.

CTI-based
server

Responsible for Computer Telephony Integration,
which integrates a network’s telephone and
computer systems.

Client and Server Operating Systems
To ensure functionality of both clients and servers, operating
systems are used
Client Operating Systems

Server Operating Systems

Windows 7

Windows Server 2008

Windows Vista
Windows XP

Windows Server 2003

Windows 2000 Professional

Windows 2000 Server

Windows NT 4.0 Workstation Windows NT 4.0 Server
Windows ME/98/95

The Peer-to-Peer Model
Peer

Peers are clients that have equal
capabilities and responsibilities in
this model
• Ability to serve and request data
• No server in this model

Examples of file sharing networks
• Napster
• Gnutella
• G2

Other technologies also take
advantage of P2P file sharing:
• Skype
• VoIP

Peer

Peer

Summary
1

Network Topologies

2

Ethernet Standards

3

Peer to Peer vs. Client/Server
Models

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