Download Physical Topologies (cont.)

Chapter 4
Network Topology
and Design
1
Contents
ÆPhysical Topologies
ÆNetwork Architecture
ÆMedia
ÆPerformance Considerations
ÆLAN Design Model
ÆReview Questions
2
Physical Topologies
„The three most common
topologies are the bus,
star, and ring.
3
Physical Topologies (cont.)
„Bus
5 A bus
topology
connects all stations in
a linear fashion, which
accounts for the name
“linear bus.” Fig. 4-1
illustrates this concept.
4
Physical Topologies (cont.)
„Bus (cont.)
5The merits of bus topology
XIt is inexpensive.
YIt is easy to design and
implement because the
stations are simply daisychained together.
5
Physical Topologies (cont.)
„Bus (cont.)
5The drawbacks of bus topology
XIt is difficult to troubleshoot.
YIt requires termination.
6
Physical Topologies (cont.)
„Star
5 The star
network
configuration
which
shown in Fig. 4-2 is the
most popular physical
topology.
7
Physical Topologies (cont.)
„Star (cont.)
5The merits of star topology
XA break in one cable does
not affect all other stations.
YIt is easy to troubleshoot.
p It does not
termination.
require
8
Physical Topologies (cont.)
„Star (cont.)
5The drawbacks of star topology
X Hubs are more expensive
than bus connectors.
YA failure at the hub can
affect
the
entire
configuration.
pStar topologies use more
cable than bus topologies.
9
Physical Topologies (cont.)
„Ring
5
Ring
network
configurations are most
seen in Token Ring and
FDDI
(Fiber
Data
Distributed Interface).
10
Physical Topologies (cont.)
Toekn Ring
11
Physical Topologies (cont.)
FDDI
12
Physical Topologies (cont.)
„Ring (cont.)
5The merits of ring topology
X It
prevents
collisions.
network
oEach station functions as
a repeater, so it does not
require additional network
hardware, such as hubs.
13
Physical Topologies (cont.)
5The drawbacks of ring topology
XTo add a station, you must
shut down the network
temporarily.
YA failure at one point can
bring down the network.
pMaintenance on a ring is
more difficult than on a
Star topology.
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Physical Topologies (cont.)
„Influence of the 5-4-3 Rule
on Topologies
5 The IEEE identifies a
maximum
number
of
repeaters,
segments,
and
populated segments that can
be used on any 10 Mbps
Ethernet network. (see Fig. 4-3)
15
Physical Topologies (cont.)
5In Fig. 4-4, one violation of
the 5-4-3 rule exists: the
separation between St. 3 and
Server 1 and Host 2 because
six segments and five
repeaters
exist
between
these stations.
16
Physical Topologies (cont.)
5 Either the hub and
segment of Station 3
must be removed, or the
hub and segments of
Server 1 and Host 2 must
be removed.
17
Contents
ÆPhysical Topologies
ÆNetwork Architecture
ÆMedia
ÆPerformance Considerations
ÆLAN Design Model
ÆReview Questions
18
Network Architecture
„IEEE 802
5 The IEEE 802 covers
issues concerning all
types of networks- LAN,
MAN, WAN, wireless.
19
Network Architecture (cont.)
„IEEE 802 (cont.)
5This section covers the
following specifications:
n802.2: LLC
o802.3: CSMA/ CD
p802.5: Token Ring
q802.11: WLAN
20
Network Architecture (cont.)
„IEEE 802 (cont.)
5 Please
study
the
contents from pages 121
to 125 by yourself.
21
Contents
ÆPhysical Topologies
ÆNetwork Architecture
ÆMedia
ÆPerformance Considerations
ÆLAN Design Model
ÆReview Questions
22
Media
„ Three types of media
commonly
used
in
network:
nTwisted-pair Cable
oCoaxial Cable
pFiber-Optic Cable
23
Media (cont.)
„
Please study the
contents from pages 126
to 134 by yourself.
24
Horizontal Cabling Standards
„
Please study the
subsection: Horizontal
Cabling Standards from
pages 134 to 138 by
yourself.
25
Contents
ÆPhysical Topologies
ÆNetwork Architecture
ÆMedia
ÆPerformance Considerations
ÆLAN Design Model
ÆReview Questions
26
Performance Considerations
„
When designing a
network, you must keep
in mind the network
performance needs of
the customer.
27
Performance Considerations (cont.)
„
Items you should
consider include:
nConnection speed
oUtilization and broadcast
traffic
pCollisions and contention
qResource placement
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Performance Considerations (cont.)
5 Transmission time
6
For
example,
the
transmission time for a file
size 300 MB transmitted
under the speed of 56
Kbps is
2,400,000 / 56,00 = 42,857 s
(or 11 hrs, 54 mins, and 17 secs)
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Performance Considerations (cont.)
5 Throughput
6 For example, it takes six
minutes for a file size 4 GB
completely
transmitted.
The
throughput
is
calculated by
32,000,000,000 / 360 = 88,888,889 bps
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Performance Considerations (cont.)
5 Collisions and contention
6 When you are considering
upgrading an existing network,
you can check the rate of
collisions on the network
using a protocol analyzer or
other network performancemonitoring tools.
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Performance Considerations (cont.)
5 Resource placement
6 Network users should be
on the same network
segment as the resources
they need to access. (see
Fig. 4-14)
32
Testing Cable
33
Testing Cable (cont.)
34
Contents
ÆPhysical Topologies
ÆNetwork Architecture
ÆMedia
ÆPerformance Considerations
ÆLAN Design Models
ÆReview Questions
35
LAN Design Models
„ There are two basic
design strategies that are
typically followed:
5Mesh design
5Hierarchical design
36
LAN Design Models (cont.)
„ In a mesh design, there is
no clear definition of where
certain
network function
are performed.
„ In Fig. 4-24, the mesh is a
flat structure in which
expansion of the network is
done laterally.
37
LAN Design Models (cont.)
„ Hierarchical design, on
the other hand, are more
structure and defined.
„ These types of designs
separate
different
equipment and network
media
by
their
connectivity functions.
38
LAN Design Models (cont.)
„ Compared with a mesh
design, a hierarchical design:
5Is easier to manage
5Is easier to troubleshoot
5Has improved scalability
5Allow easier analysis
39
LAN Design Models (cont.)
„
Three hierarchical
network models: the
three-layer model, the
two-layer model, and
one-layer
model
are
described
in
this
subsection.
40
LAN Design Models (cont.)
„ Three-layer Network Model
5 The three-layer network
model
is
the
most
complex of the three
models. It contains a core
layer, a distribution layer,
and an access layer.
41
LAN Design Models (cont.)
„ Three-layer Network Model (cont.)
5 Core layer: Provides
WAN
connectivity
between sites located in
different geographical
areas.
42
LAN Design Models (cont.)
„ Three-layer Network Model (cont.)
5
Distribution layer:
Used to interconnect
building with separate
LANs on a campus
network.
43
LAN Design Models (cont.)
„ Three-layer Network Model (cont.)
5 Access layer: Identifies
a LAN or a group of
LANs that provides
users with access to
network services.
44
LAN Design Models (cont.)
„ Three-layer Network Model (cont.)
5 Fig. 4-25 illustrates
how each layer would
be categorized in a large
network.
45
LAN Design Models (cont.)
„ Two-layer Network Model
5 Network administrators
use WAN connections
to
interconnect
separate
LANs,
as
shown in Fig. 4-26.
46
LAN Design Models (cont.)
„ One-layer Network Model
5
Smaller networks can
employ a
one-layer
network model strategy.
5
Servers
may
be
distributed across the LAN
or placed in one central
location. (see Fig. 4-27)
47
Network Management Tools
„ SNMP
5 The Simple Network
Management Protocol
(SNMP) is a
TCP/IP
standard
protocol
included in all major
TCP/IP protocol suit.
48
Network Management Tools
„ SNMP (cont.)
5
SNMP
is
a
connectionless protocol
that operates at layer 7 of
OSI model and port
number 161.
49
Network Management Tools (cont.)
„ SNMP (cont.)
50
Contents
ÆPhysical Topologies
ÆNetwork Architecture
ÆMedia
ÆPerformance Considerations
ÆLAN Design Model
ÆReview Questions
51
Review Questions
‹ Which of the following UTP
cable types are not rated for
at
least
100
Mbps
transmission? (choose 2)
A. Cat. 3
B. Cat. 4
C. Cat. 5
D. Cat. 6
Ans: C, D
52
Review Questions (cont.)
‹ Which of the following are
benefits to installing fiberoptic cable? (choose all that
apply)
A. Impervious to EMI
B. Small diameter
C. Easy to install
D. Low cost
Ans: A, B
53
Review Questions (cont.)
‹Which of the following is the
correct
specification
for
wireless technologies?
A. 802.3
B. 802.5
C. 802.11
D. 802.4
E. None of the above
Ans: C
54
Review Questions (cont.)
‹ Which of the following
specification
defines
Token Ring?
A. 802.3
B. 802.5
C. 802.11
D. 802.4
E. None of the above
Ans: B
55
Review Questions (cont.)
‹Which of the following is an
advantage to using the bus
topology?
A. Centralized connection point
B. Low implementation cost
C. Easy of troubleshooting
D. Fault tolerate
Ans: B
56
Review Questions (cont.)
‹Which type of connector is
used with twisted-pair
cabling?
A. BNC
B. SC
C. T-connectors
D. RJ-45
E. None of the above
Ans: D
57
Review Questions (cont.)
‹ Which of the following
cables have shielding that
protect them from EMI?
(choose all that apply)
A. Fiber-optic
B. RG-58
C. STP
D. UTP
Ans: A, B, C
58
Review Questions (cont.)
‹ Which wireless technology
requires line-of-sight between
the transmitter and receiver?
A. Spread spectrum
B. Direct sequencing
C. Frequency hopping
D. Infrared
E. None of the above
Ans: D
59
Review Questions (cont.)
‹The usable distance of the
UTP cable between MDF
and IDF is ____ meters.
Ans: 100
60
Review Questions (cont.)
‹If single-mode fiber-optic
cable is used between
MDF and IDF, what is the
maximum usable distance.
Ans: 3,000 meters
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