Transcript Network Topologies / Configurations Presentation

NETWORKS
Network Topologies / Configurations
Learning Objectives
Describe for each type of network topology
the relative strengths and weaknesses.
Network Topologies /
Configurations
Networks can have their computers
connected in a number of different ways.
Each method has its advantages and
disadvantages.
BUS
Workstation
Workstation
terminator
terminator
Workstation Workstation Workstation Workstation Workstation
Advantage:


Simple and cheap to set up.
Out of all the topologies the bus topology uses the least cabling.
Disadvantages:



If there is a break in the main cable, the entire network stops working
and for this reason adding workstations disrupts the entire network
(there needs to be a terminator on both ends of the cable for it to work).
A busy (many workstations or a lot of traffic) bus network will have many
data collisions and so will be VERY slow (slowest network topology).
Data trying to travel simultaneously along the cable in different directions
is called a 'data collision'.
Poor security as messages do not have to go through the server.
Advantage:

If there is a break in the cable,
the network will continue to
operate because the messages
can go in the other direction.
RING
The workstations themselves
now act as terminators.




Simple and cheap to set up as
cabling is minimal (more than Bus
but less than Star).
One direction is chosen for data
transmission (changed only if cable
is broken as explained above) so
data collisions are prevented.
Performs better than any other
topology under heavy network
traffic (load).
Can be used for wide area
networks.
Server
Workstation
Workstation
Disadvantage:


Adding workstations does not
stop the network but messages
have to go the other way so the
network traffic is slowed.
Poor security as messages do
not have to go through the
server.
Workstation
Workstation
Workstation
STAR
Advantage:


Reliable - new stations may be
added / deleted / damaged and
cables between workstations
and the hub broken without
affecting the network at all.
Good data security - no
workstation can interact with
another without going through
the server first.
Workstation
Workstation
Server
Workstation
Workstation
Workstation
Disadvantage:


Complex wiring - lots of cables
required.
Extra hardware required such as
hubs (or switches see right).
Notes:
1. A STAR network dictates that all messages travel
via the server on their way to their destination.
2. If the central point is a ‘switch’ instead of a ‘hub’
then data collisions are prevented as the switch
controls communications (a hub however just
relays all communications so data collisions can
still occur).
3. If the hub breaks down or the cable hub <-> server
breaks then the whole network goes down.
Peripherals
Printers, scanners etc…. are often
known as peripherals and are often
shared by connecting them to the
server, rather than directly to the network
as shown in previous diagrams.
Comparing Topologies
When asked to compare topologies do not
use an advantage or disadvantage if they
also apply to the other/s.
Bus:

Bus
Vs
Ring
Simple and cheap to set up.
Advantage:
Out of all the topologies the bus topology uses the least cabling.

Disadvantages:
If there is a break in the main cable, the entire network stops
working.
A busy (many workstations or a lot of traffic) bus network will have many
data collisions and so will be VERY slow (slowest network topology).
Ring:

Advantage:
Performs better than any other topology under heavy network traffic
(load).
If there is a break in the cable, the network will continue to operate
because the messages can go in the other direction.
One direction is chosen for data transmission (changed only if cable is
broken as explained above) so data collisions are prevented.
Can be used for wide area networks.

Disadvantage:
Slightly more difficult to set up than the BUS topology and if one
workstation is off or a workstation is added, network traffic is slowed
(but not stopped) as messages have to travel in the other direction
(one workstation being switched off in a BUS has no affect at all on the
network).
BUS Vs STAR
Bus:

Advantage:
Simple and cheap to set up.
Out of all the topologies the bus topology uses the least cabling.

Disadvantages:
If there is a break in the main cable, the entire network stops
working and for this reason adding workstations disrupts the entire
network.
A busy (many workstations or a lot of traffic) bus network will have many
data collisions and so will be VERY slow (slowest network topology).
Poor security as messages do not have to go through the server.
Star:

Advantage:
Reliable - new stations may be added / deleted / damaged and
cables between workstations and the hub broken without affecting
the network at all.
Good data security - no workstation can interact with another
without going through the server first.

Disadvantage:
Complex wiring - lots of cables required.
Extra hardware required such as hubs (or switches).
RING Vs STAR
RING:

Advantage:
Performs better than any other topology under heavy network traffic (load).
Simple and cheap to set up.
Less cabling than a STAR network topology.

Disadvantages:
Adding workstations does not stop the network but messages have to go the
other way so network traffic is slowed.
Poor security as messages do not have to go through the server.
Star:

Advantage:
Reliable - new stations may be added / deleted / damaged and cables
between workstations and the hub broken without affecting the network at
all.
Good data security - no workstation can interact with another without going
through the server first.

Disadvantage:
Complex wiring - lots of cables required.
Extra hardware required such as hubs (or switches).
BUS Vs RING Vs STAR
Bus:

Advantage:
Simple and cheap to set up.
Out of all the topologies the bus topology uses the least cabling.

Disadvantages:
If there is a break in the main cable, the entire network stops working and for this reason adding
workstations disrupts the entire network.
A busy (many workstations or a lot of traffic) bus network will have many data collisions and so will be
VERY slow (slowest network topology).
Ring:

Advantage:
Performs better than any other topology under heavy network traffic (load).
Can be used for wide area networks.
Breaks in any cables do not stop the network but network traffic is slowed.


If the hub breaks down or the cable hub <-> server breaks in a STAR then the whole network goes down.
Disadvantage:
Adding workstations does not stop the network but messages have to go the other way so the
network traffic is slowed.
Star:

Advantage:
Reliable - new stations may be added / deleted / damaged and cables between workstations and
the hub broken without affecting the network at all.
Good data security - no workstation can interact with another without going through the server first.

Disadvantage:
Complex wiring - lots of cables required.
Extra hardware required such as hubs (or switches).
Plenary
Describe each type of network topology
and give their relative strengths and
weaknesses.
BUS
Workstation
Workstation
terminator
terminator
Workstation Workstation Workstation Workstation Workstation
Advantage:


Simple and cheap to set up.
Out of all the topologies the bus topology uses the least cabling.
Disadvantages:



If there is a break in the main cable, the entire network stops working
and for this reason adding workstations disrupts the entire network
(there needs to be a terminator on both ends of the cable for it to work).
A busy (many workstations or a lot of traffic) bus network will have many
data collisions and so will be VERY slow (slowest network topology).
Data trying to travel simultaneously along the cable in different directions
is called a 'data collision'.
Poor security as messages do not have to go through the server.
Advantage:

If there is a break in the cable,
the network will continue to
operate because the messages
can go in the other direction.
RING
The workstations themselves
now act as terminators.




Simple and cheap to set up as
cabling is minimal (more than Bus
but less than Star).
One direction is chosen for data
transmission (changed only if cable
is broken as explained above) so
data collisions are prevented.
Performs better than any other
topology under heavy network
traffic (load).
Can be used for wide area
networks.
Server
Workstation
Workstation
Disadvantage:


Adding workstations does not
stop the network but messages
have to go the other way so the
network traffic is slowed.
Poor security as messages do
not have to go through the
server.
Workstation
Workstation
Workstation
STAR
Advantage:


Reliable - new stations may be
added / deleted / damaged and
cables between workstations
and the hub broken without
affecting the network at all.
Good data security - no
workstation can interact with
another without going through
the server first.
Workstation
Workstation
Server
Workstation
Workstation
Workstation
Disadvantage:


Complex wiring - lots of cables
required.
Extra hardware required such as
hubs (or switches see right).
Notes:
1. A STAR network dictates that all messages travel
via the server on their way to their destination.
2. If the central point is a ‘switch’ instead of a ‘hub’
then data collisions are prevented as the switch
controls communications (a hub however just
relays all communications so data collisions can
still occur).
3. If the hub breaks down or the cable hub <-> server
breaks then the whole network goes down.