Transcript Semester 1 Chapter 8 - Institute of Technology Sligo

Institute of Technology Sligo - Dept of Computing
Chapter 8
Network Design and
Documentation
Institute of Technology Sligo - Dept of Computing
In previous chapters you learned :
•OSI model and data encapsulation
process .
•Different LAN technologies.
•Layers 1 & 2 concepts and technologies.
In this chapter you will start learning
network design and documentation
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GENERAL DESIGN PROCESS
 Network design takes into consideration
the following LAN technologies:
• Token-Ring
• FDDI
• Ethernet (focus of the curriculum)
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• Ethernet
has
- logical bus topology which leads to:
Collision domains;
- Your responsibility is to minimize them by:
segmentation
•Once you have chosen Ethernet technology
you must develop:
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 Step 1:
•Layer 1 topology:
- Type of cable (most common is CAT 5)
- Physical topology (extended star)
- You may need to use hubs, repeaters,
transceivers and other layer 1 components
- Which type of Ethernet to be used:
10Base-T or 100Base-TX
Layer 1 design finished with physical & logical
topologies designed.
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 Step 2:
•Layer 2 design:
-implementation of switches to reduce collision
domain size.
- VLAN design (sem- 3).
-replacing hubs with switches for existing
devices.
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 Step 3:
•Layer 3 design:
- layer three devices (routers) to access
WAN services & internet.
- or you may need routers to segment
broadcast domains & to add more security
between different network segments.
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Network design issues
•First step in the design process is
- to gather information about the organization:
- Users requirements
- types of applications
- projected growth
- operating policies & procedures
- people who will be using the network
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•Second step
- Detailed analysis of gathered data:
For example:
* Based
on user requirements, numbers of users,
and applications types you can determine:
- bandwidth per user : 10, 100 MBS;
- type of H/W : hubs, switches, vlans;
- types of horizontal & backbone cabling
* Based
on projected growth, you may determine
the scalability of your network:
- number of switches in MDF and/or IDF
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- Number and speed of ports per switch / hub
- number and speed of ports to be used for backbone
interconnections
* Based on type of applications you may determine:
- to divide users into groups in order to implement VLANs
- bandwidth per each user/group of users.
- placement of servers:
some applications are accessed by all users (DNS, EMail,…..), other applications are specific (financial, video
training,…)
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•Third step
- identify resources & constraints of the
organization:
- existing computer H/W
- existing S/W resources
- human resources
- organization’s budget
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- During your network design you will create
the following documents:
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Engineering journal.
Logical topology.
Physical topology.
Cut sheets.
Problem-solving matrices.
Labeled outlets.
Labeled cable runs.
Summary of outlets and cable runs.
Summary of devices, addresses.
Institute of Technology Sligo - Dept of Computing
Institute of Technology Sligo - Dept of Computing
Institute of Technology Sligo - Dept of Computing
Institute of Technology Sligo - Dept of Computing
Institute of Technology Sligo - Dept of Computing
Institute of Technology Sligo - Dept of Computing
Institute of Technology Sligo - Dept of Computing
Planning structured cabling:
wiring closet specifications
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Overview of wiring closet
One of the early decisions is:
- Selection of wiring closets (MDF/
IDF) according to standards.
- MDF is where many of networking
devices and cables will be installed
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Cabling standards
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Wiring closet specifications:
• Services as a central point of a star
topology (TIA/EIA 568A standard)
• Where the horizontal cabling runs
must be attached
• Where the patch panels and
switches/ hubs must be installed.
• Must be large enough to accommodate
equipment and extra space for future
growth:
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Institute of Technology Sligo - Dept of Computing
•Each floor must have at least one wiring
closet
•One wiring closet should be added for
each 1000 m2 or the horizontal cable
distance exceeds 90m..
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Environmental specifications
Selected room/ closet should satisfy certain
requirements for:
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Materials for walls, floors, and ceilings.
Temperature and humidity.
Locations and types of lighting.
Power outlets.
Room and equipment access.
Cable access and support.
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•Walls , floors and ceiling
Rooms must
not have a
dropped, or
false, ceiling
20mm
plywood
that is at
least
2.4m
Minimum load capacity.
Raised floor or Ladder Rack Support.
Tiled, or some other type of finished surface.
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•VHAC
- Temperature: 21o.
- humidity: 30 – 50%.
- No water or steam pipes running
through or above the room.
•Lighting and power outlets:
- minimum of two dedicated, non switched, AC duplex electrical outlets.
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- At least one duplex power outlet
positioned every 1.8 m along each wall..
- power outlet should be positioned 150
mm above the floor.
- main lighting control switch should
be placed immediately inside the door
- florescent lighting should be avoided
for cable pathways.
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•Room and equipment access:
- door should be at least 0.9 m wide;
- door should open out of the room;
- switches/ hubs and patch panel may be
mounted:
- to wall using hinged wall bracket;
- with distribution rack;
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Institute of Technology Sligo - Dept of Computing
Wiring hub and patch
panel were mounted to
a wall with a hinged
wall bracket.
Wiring hub and patch panel
were mounted with distribution
rack
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Institute of Technology Sligo - Dept of Computing
- All horizontal cabling that runs from work areas to a
wiring closet should be run under a raised floor;
- When this is not possible, the cabling should be run
through 10.2 cm sleeves that are placed above door level.
- any wall/ ceiling openings should be sealed with a smoke
and flame-retardant materials
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Wiring closet identification
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- You may think of a hub as a central point of a circle which has
horizontal cables radiating from it.
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• In order to determine the location of wiring closet
begin by drawing the floor plan;
•Add devices that will be connected to network;
• identify secure locations to be used as MDF/IDF;
• MDF should be close to the POP;
• determine number of wiring closets;
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Institute of Technology Sligo - Dept of Computing
• draw circles of radius 50 m from each potential
wiring closet (hub location)
• if there are any potential wiring closets whose
catchments areas substantially overlap, you may
eliminate one of them.
• if the catchment area does not cover all devices,
repeaters are used (IDF).
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Institute of Technology Sligo - Dept of Computing
Institute of Technology Sligo - Dept of Computing
MDF location in multi-story building
MDF is located on
one of the middle
floors, even though
the POP might be
located on the first
floor.
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MDF location in multi-building campus
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Backbone cabling consists of:
• Backbone cabling runs
•Intermediate and main cross-connects.
•Patch cords used for backbone – to
–backbone cross – connection:.
•Vertical media between wiring
closets on different floors.
•networking media between MDF
and POP.
•Networking media used between
buildings in multi-building campus.
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Institute of Technology Sligo - Dept of Computing
Backbone cabling media
•According to TIA/EIA 568 A, four
type of networking media can be
Used for backbone cabling:
- 100  UTP (four – pair).
- 150  STP (two – pair).
- multimode optical fiber
- single mode optical fiber.
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•IDF can be connected to MDF in two ways:
1. IDF can be connected directly to MDF
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2. 1st IDF connected to 2nd IDF; the 2nd is
then connected to MDF;
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• No work areas are connected to ICC;
• No more than one ICC can be passed
through to reach MDF
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•Maximum distance for backbone cabling:
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Institute of Technology Sligo - Dept of Computing
Institute of Technology Sligo - Dept of Computing
Electricity and Grounding
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• DC current flows in a constant value
Examples: flashlight, car battery,
computer motherboard
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Institute of Technology Sligo - Dept of Computing
•AC noise:
• AC noise all around us:
in walls, ceilings, floors
• AC noise can come from:
- from video monitors, H/D drives
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•Electrostatic static discharge (ESD)
• Static electricity: stationary electrons.
• Most damaging and uncontrollable
Form of electricity.
• ESD destroy semiconductors and data.
• A solution that can help solve ESD
problem: good grounding.
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•Safety ground
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• Safety ground wire is connecting to
any exposed metal of the equipment
• Motherboards and computing circuits
in computers are connected to chassis
this connects them to safety ground.
• Safety ground prevents metal parts
from becoming energized.
• It serves as a low resistance path to
the earth when a faulty connection
between a hot line and chassis occurs.
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•Multi-ground connections
• Large buildings frequently require
more than one earth ground.
• Separate earth grounds also required
in multi-building campus.
• Earth grounds between buildings is
almost never the same. Also separate
earth grounds for the same building
may vary.
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• When separate ground wires have
different potential (voltage) to the
common and hot wires they can
present a serious problem
• If a circuit is established between
devices in two buildings, then a current
Would flow from negative to positive
Source
• Such circuit could cause a nasty shock,
and it may damage memory chips.
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Institute of Technology Sligo - Dept of Computing
• A good way to avoid current pass
through the body, and through the
heart, is to use one hand rule.
•Avoiding dangerous circuits between buildings
• TIA/EIA-568- standards recommends
the use of optical fiber for backbone
connections (between buildings, and
between different floors within the
same building.
• Optical fiber is a good insulator:
Electricity does not travel over fiber.
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Network power supply issues
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•Power problem classification
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• Normal mode problem:
- don’t pose a hazard to you or to
your computer .
• Common mode problem:
- Can go directly to computer’s
chassis, they can damage data
signals.
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•Typical Power line problems:
• Sag (brownout):
- short term decrease in voltage level
- duration : less than a second
- cause: equipment startup (motors, elevators)
-effects: lost or corrupted data, shrinking
screen, equipment shutdown
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- Possible solutions:
-relocate a computer to a different electrical
circuit.
- voltage regulators.
- UPS.
Institute of Technology Sligo - Dept of Computing
Institute of Technology Sligo - Dept of Computing
• Total power loss:
- cause: excessive demand on power grid.
-Lighting storms.
-Ice on power lines
-Car accidents
- effects: system shutdown.
- Possible solutions:
- UPS.
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Institute of Technology Sligo - Dept of Computing
• Spike:
- instantaneous increase in voltage (microseconds).
-cause: nearby lighting strike, equipment cycle
on or off.
- effect: hardware damage, lockups, data loss.
Solution:
-surge suppressors
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Institute of Technology Sligo - Dept of Computing
• surge:
- a short term increase in voltage (a few seconds)
-cause: high- powered electrical devices is
switched off.
- effects:hardware damage, lockups, data loss
Solution:
-surge suppressors.
Institute of Technology Sligo - Dept of Computing
Institute of Technology Sligo - Dept of Computing
• Oscillation (harmonics or noise):
-unwanted electrical signal of high frequency
form other equipment (RFI, EMI).
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-disrupts the smooth sine wave expected from
utility power.
- cause: lighting, generators, radio transmitters,
excessively long electrical wiring run.
- effects: data loss, errors.
Solution:
-shortening power cable runs.
-power line filtration.
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Institute of Technology Sligo - Dept of Computing
• UPS
- sag and brownout problems best
addressed by UPS.
- At minimum, every network file server
should have a UPS.
- Where possible a power backup should
be provided for all work areas.
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Types of UPS:
1. Standby (off-line or switched) ups
2. On-line (continuous) UPS.
3. Line-interactive UPS.
Institute of Technology Sligo - Dept of Computing
Institute of Technology Sligo - Dept of Computing
Good Luck !