Network Design and Documentation

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Chapter 8 Network Design and Documentation
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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, E-Mail,..), 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
- organizations budget
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- During your network design you will create
the following documents

• 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.

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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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• 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

• 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

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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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• 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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- 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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• 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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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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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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Electricity and Grounding
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• DC current flows in a constant value

Examples flashlight, car battery,
computer motherboard
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• 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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• 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

• dont pose a hazard to you or to
• your computer .

• Common mode problem

• Can go directly to computers
• 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.
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• 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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• 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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• surge

- a short term increase in voltage (a few seconds)
-cause high- powered electrical devices is
switched off.
- effectshardware damage, lockups, data loss
Solution
-surge suppressors.
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• 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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• 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.
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Good Luck !