There
are three main types of topologies
that
are bus, star and ring topology.
Each topology has
certain characteristics that should be used as a guideline by the network
designers in their selection of a
topology.
The more
expensive the topology the more efficient, fast, reliable and specialized the
topology is to implement.
-
To
have all computers communicate with each other on a network
. These computers include Servers,
Workstations
, PDA’s, Laptops, and printers
-
Local
Area Network
(LAN
) that is a set of computer
connected together through repeaters, hubs, bridges, or switches in one
location.
-
In
bus topology all computers use the same cable
medium
called the backbone
to
communicate to each other.
-
A
coaxial
cable
is
used for the backbone
, which could be one of 2 wires
called Thinnet
(10base2)
or Thicknet
(10base5).
-
Thinnet
(10base2)
cable
is
fairly flexible and is used between the terminals in the network
-
Thicknet
(10base5)
cable
is
rigid and has a lot of shielding
to
allow it to send the data for a longer distance between rooms over the
ceiling.
-
A break in the cable
will allow the signals to
bounce in the cable causing data collision that will stops the operation
of the whole network
.
-
The
second draw back to this topology is that if the network
stops
working it is very difficult to diagnose where the break occurred in the
network.
-
This topology uses an
economical amount of cable
.
-
The
star topology has individual twisted pair
connections
from each computer to a centralized
hub
that
connects all the computers connected to its ports together.
-
The Star topology
is currently by far the most
popular topology because its fairly cheap, reliable, and fast.
-
This
topology comes in two main network
speed
10baseT
and
100baseT
-
10baseT
transmits data at 10Mb/s and
100baseT
transmits data at 100Mb/s.
-
This topology has increased the
networks reliability
because if there is a break in
any cable
, only that computer will lose its network
connection, which will not
effect the operation of the rest of the network.
-
Troubleshooting has been made
easier because the breakage or malfunction is on the port where the
network
connection does not work.
-
Twisted
Pair medium uses pairs of wires twisted as much as possible to transfer
the data.
-
The first wire in the pair has
the data; the second wire has the inverse of the data.
-
External noise is calculated
from the pair of wire and removed.
·
Both wires can be assumed to have been effected by the same
amount of external noise.
·
Two main types Unshielded Twisted Pair (UTP
) that has the pair in a plastic sheath, and Shielded Twisted Pair (STP
), which has extra shielding
in the form of foil, wrapped
around each pair.
-
The
ring topology network
principally
follows a closed loop
backbone
where
all the computers connect to this backbone.
-
Principally if there is a
breakage anywhere in the network
, the whole network will go down.
-
Practically
the backbone
is
within a hub
known
as the Multistation Access Unit (MAU
) that has 8 ports for computer to
connect and access the network
-
MAU
’s provide the ring topology with a certain amount of reliability
because if one port has a
breakage in the network
, the MAU will disconnect that port allowing the rest of the network to
function normally.
-
Sometimes
referred as Token Ring
because
there is a digital token
sent
around the network
which
any computer within the loop
can
pickup, and only the computer with the token can talk.
-
The
token
ensures
that only one computer transmits at any time and there are no packet
collisions
on
the network
-
Fiber optic
cables have a layer of glass
that is surrounded by plastic fibers inside a cladding and transmit data
only in one direction.
-
Fiber optic
cables use two wires for each
connection between the computer and the MAU
because one wire transmits the
data from the MAU to the computer’s network
card and the other transmits
the data from the computer to the MAU.
-
The fiber optic network
card has two ports on it
labeled as ST and SC for transmitting and receiving data.
·
Fiber optics cables can
transmit data packets up to 1Gb/sec.
-
They
can transmit data any distance from 1m to several kilometers without
amplification.
-
Fiber optic
lines are highly secure and
make it almost impossible to eavesdrop on.
-
Fiber optic
lines are very expensive both
in materials and installation
cost because it is very
specialized.
Questions
1) What does
TOPOLOGY mean in a network
?
a) Network design
b) Physical
layout of network
c) Logical layout
of network
d) Access method
of network
2) What are the
different designs of bus topology? (Choose all that apply)
a) 10 base 8
b) 10 base T
c) 10 base 2
d) 10 base 5
e)
10 base 9
3) What are the
different designs of Star topology
? (Choose all that apply)
a) 10 base 8
b) 10 base T
c) 10 base 2
d) 10 base 5
e) 100 base T
4) Thicknet
is the same as?
a) 10 base 8
b) 10 base T
c) 10 base 2
d) 10 base 5
e) 100 base T
5) What does the
2 mean in 10 base 2?
a) 2MB/s
b) 200m
c) 200KB/s
d) 2x10 Mb/s
e) 2Km
6) What cable
is used in a 10 base T network
?
a) Twisted pair
b) Coaxial
c) Fiber optic
d) Twisted
Coaxial
e) Fiber optic
pair
7) What are the
advantages of using the star topology? (Choose all that apply)
a) Easy
troubleshooting
b) If one
computer network
connection fails, the rest of the
network remains unaffected
c) Reasonably
priced
d) Not a lot of
wiring involved
e) Fast network
8) What are the
advantages of using the bus topology? (Choose all that apply)
a) Easy
troubleshooting
b) If one
computer network
connection fails, the rest of the
network remains unaffected
c) Reasonably
priced
d) Not a lot of
wiring involved
e) Fast network
9) What are the
advantages of using the ring topology? (Choose all that apply)
a) Easy
troubleshooting
b) If one
computer network
connection fails, the rest of the
network remains unaffected
c) Reasonably
priced
d) Not a lot of
wiring involved
e) Fast network
10) What is the
category of the wire used 100baseT
?
a) cat 1
b) cat 2
c) cat 3
d) cat 4
e) cat 5
11) What are the
advantages of using a fiber optic medium? (Choose all that apply)
a) Very fast
b) Cheap
c) Very secure
d) Very Reliable
e) Easy to
install
Answers
-
B
-
C,D
-
B,E
-
D
-
B
-
A
-
A,B,C,E
-
C,D
-
A,B,E
-
E
-
A,C,D