Chapter 10 – Networking Types
Aims:
Define the infrastructure of networks.
Outline the differing networking topologies.
Outline the main networking technologies.
Interconnection of networks
BACKBONE2
LAN
LANBB
BACKBONE1
LAN
LANAA
LAN
LANDD
Bridge
Bridgeor
or
router
router
LAN
LANCC
Local network
LAN
LANEE
LAN
LANFF
Local network
Local network
Bridge
Bridgeor
or
router
router
Local network
Local network
BACKBONE3
Network topologies
Central
server
Ring network
Star network
Bus network
Tree topologies
Network backbone
Concentrator
(or hub)
Concentrator
(or hub)
Star topology
Central
server
Star
StarNetwork
Network
Advantages:
Advantages:
Since
Sincethe
thedata
datarate
rateisisrelatively
relativelylow
lowbetween
betweencentral
central
server
and
the
node,
a
low-specification
twisted-pair
server and the node, a low-specification twisted-pair
cable
cable can
can be
be used
used toto connect
connect the
the nodes
nodes toto the
the
server.
server.
AAfault
faulton
onone
oneofofthe
thenodes
nodeswill
willnot
notaffect
affectthe
therest
rest
ofofthe
network.
Typically,
mainframe
computers
use
the network. Typically, mainframe computers use
aacentral
centralserver
serverwith
withterminals
terminalsconnected
connectedtotoit.it.
Disadvantages:
Disadvantages:
Network
Networkisishighly
highlydependent
dependentupon
uponthe
theoperation
operationofof
the
the central
central server.
server. IfIf itit were
were toto slow
slow significantly
significantly
then
the
network
becomes
slow.
In
addition,
then the network becomes slow. In addition, ifif itit
were
weretotobecome
becomeun-operational
un-operationalthen
thenthe
thecomplete
complete
network
would
shut
down.
network would shut down.
Token passing ring network
Electronic token
is passed from
node to node
Nodes can only
transmit data when
they capture
the token
Advantages:
Advantages:
All
Allnodes
nodeson
onthe
thenetwork
networkhave
haveananequal
equalchance
chanceofof
transmitting
data.
transmitting data.
Disadvantages:
Disadvantages:
IfIfone
oneofofthe
thenodes
nodesgoes
goesdown
downthen
thenthe
thewhole
whole
network
may
go
down.
network may go down.
Token
Tokenmay
mayget
getlost,
lost,or
ormany
manytokens
tokensare
aregenerated.
generated.
Difficult
Difficulttotoadd
addand
anddelete
deletenodes
nodesto/from
to/fromthe
thering.
ring.
Token
TokenRing
Ring
Orderly
Orderlyaccess
accesstotoring.
ring.
Single
electronic
token
Single electronic tokenpasses
passesfrom
fromone
onecomputer
computer
totothe
next
around
the
ring.
the next around the ring.
Computer
Computercan
canonly
onlytransmit
transmitdata
datawhen
whenititcaptures
captures
the
token.
the token.
Each
Eachlink
linkbetween
betweennodes
nodesisisaapoint-to-point
point-to-pointlink
link
and
allows
the
usage
of
almost
any
type
of
and allows the usage of almost any type of
transmission
transmissionmedium.
medium.
Typically,
Typically,twisted-pair
twisted-paircables
cablesallow
allowaabit
bitrate
rateofofup
uptoto
16
16Mbps,
Mbps,but
butcoaxial
coaxialand
andfibre-optic
fibre-opticcables
cablesare
are
normally
used
for
extra
reliability
and
higher
normally used for extra reliability and higherdata
data
rates.
rates.
AAtypical
typicalring
ringnetwork
networkisisIBM
IBMToken
TokenRing
Ringand
and
FDDI.
FDDI.
Bus topology
All computers have access to
a common bus at the same time
Common bus
Ethernet hub
Bus
Busnetwork
network
Uses
Usesaamulti-drop
multi-droptransmission
transmissionmedium.
medium.
All
nodes
on
the
network
share
All nodes on the network shareaacommon
commonbus
busand
andallall
share
share communications.
communications. This
This allows
allows only
only one
one device
device toto
communicate
at
a
time.
communicate at a time.
AAdistributed
distributedmedium
mediumaccess
accessprotocol
protocoldetermines
determineswhich
which
station
is
to
transmit.
Data
frames
contain
source
station is to transmit. Data frames contain source and
and
destination
destinationaddresses,
addresses,where
whereeach
eachstation
stationmonitors
monitorsthe
thebus
bus
and
copies
frames
addressed
to
itself.
and copies frames addressed to itself.
Twisted-pair
Twisted-pair cables
cables give
give data
data rates
rates up
up toto 100
100Mbps,
Mbps,
whereas,
whereas,coaxial
coaxialand
andfibre-optic
fibre-opticcables
cablesgive
givehigher
higherbit
bitrates
rates
and
longer
transmission
distances.
Gigabit
Ethernet
is
now
and longer transmission distances. Gigabit Ethernet is now
available
available(1Gbps).
(1Gbps).
AAtypical
typicalbus
busnetwork
networkisisEthernet
Ethernet2.0.
2.0.
Advantages:
Advantages:
Good
Goodcompromise
compromiseover
overthe
theother
othertwo
twotopologies
topologiesasasititallows
allows
relatively
high
data
rates.
relatively high data rates.
IfIfaanode
nodegoes
goesdown,
down,ititdoes
doesnot
notaffect
affectthe
therest
restofofthe
thenetwork.
network.
Disadvantages:
Disadvantages:
Requires
Requiresaanetwork
networkprotocol
protocoltotodetect
detectwhen
whentwo
twonodes
nodesare
are
transmitting
at
the
same
time.
transmitting at the same time.
Does
Doesnot
notcope
copewell
wellwith
withheavy
heavytraffic
trafficrates.
rates.
Token ring data exchange
Control
Token
(a)
A
(b)
Data
Frame
Ack.
D
B
(c)
C
(d)
Control
Token
Ethernet
1
2
3
Two nodes transmit
at the same time
Nodes detect there
has been a collision
Nodes transmit a
jamming signal
CSMA/CD
CSMA/CD
Ethernet
Ethernetuses
usescarrier
carriersense,
sense,multiple
multipleaccess
accesswith
with
collision
collisiondetection
detection(CSMA/CD).
(CSMA/CD).
Nodes
Nodesmonitor
monitorthe
thebus
bus(or
(orEther)
Ether)totodetermine
determineifif
ititisisbusy.
busy.AAnode
nodewishing
wishingtotosend
senddata
datawaits
waitsfor
foranan
idle
condition
then
transmits
its
message.
idle condition then transmits its message.
Collisions
Collisionscan
canoccur
occurwhen
whentwo
twonodes
nodestransmit
transmitatat
the
thesame
sametime,
time,thus
thusnodes
nodesmust
mustmonitor
monitorthe
thecable
cable
when
they
transmit.
when they transmit.
When
When aa collision
collision occurs,
occurs, both
both nodes
nodes stop
stop
transmitting
frames
and
transmit
a
jamming
transmitting frames and transmit a jammingsignal.
signal.
This
This informs
informs allall nodes
nodes on
on the
the network
network that
that aa
collision
has
occurred.
collision has occurred.
Each
Each ofof the
the nodes
nodes involved
involved inin the
the collision
collision then
then
waits
a
random
period
of
time
before
attempting
waits a random period of time before attemptingaa
retransmission.
retransmission.
As
Aseach
eachnode
nodehas
hasaarandom
randomdelay
delaytime
timethen
thenthere
there
can
canbe
beaaprioritization
prioritizationofofthe
thenodes
nodeson
onthe
thenetwork.
network.
All computers have access to
a common bus at the same time
4
Nodes wait a random
period before retransmitting
Common bus
Repeaters, bridges and routers
Network segment (repeater
extends the network segment)
Router only forwards if the
network address is on another
network. It does not forward
broadcasts.
Repeater
Repeater
Bridge
Bridge
Bridge only forwards if the
station (or MAC) address is not
on the connected network
segment that it originated from.
Broadcasts are also passed
over.
Router
Router
Network
segment
bounded by a
router or a
bridge