institute of technology sligo - dept of computing chapter 8 network design and documentation

Institute of Technology Sligo - Dept of Computing

Chapter 8Chapter 8

Network Design Network Design and and

DocumentationDocumentation


In previous chapters you learnedIn 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


GENERAL DESIGN PROCESSGENERAL DESIGN PROCESS

Network design takes into consideration

the following LAN technologies:

• Token-Ring

• FDDI

• Ethernet (focus of the curriculum)


• 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:


Step 1: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-TXLayer 1 design finished with physical & logical topologies designed.


Step 2:Step 2:

•Layer 2 design:

-implementation of switches to reduce collision

domain size.

- VLAN design (sem- 3).

-replacing hubs with switches for existing

devices.


Step 3: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.


Network design issuesNetwork 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


•Second step

- Detailed analysis of gathered data: For example:

* Based on user requirements, numbers of users, and applications types you can determine:

- type of H/W : hubs, switches, type of H/W : hubs, switches, vlans; vlans;

* Based on projected growth, you may determine the scalability of your network:

- number of switches in MDF and/or IDF

- types of horizontal & backbone - types of horizontal & backbone cablingcabling

- bandwidth per user : 10, 100 - bandwidth per user : 10, 100 MBS;MBS;


- 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

- placement of servers:

- bandwidth per each user/group of users.

some applications are accessed by all users (DNS, E-Mail,…..), other applications are specific (financial, video training,…)


•Third step

- identify resources & constraints of the

organization:

- existing computer H/W

- existing S/W resources

- human resources

- organization’s budget


Engineering journal.Engineering journal. Logical topology.Logical topology. Physical topology. Physical topology. Cut sheets.Cut sheets. Problem-solving matrices. Problem-solving matrices. Labeled outlets. Labeled outlets. Labeled cable runs. Labeled cable runs. Summary of outlets and cable runs. Summary of outlets and cable runs. Summary of devices, addresses. Summary of devices, addresses.

- During your network design you will create the following documents:


Planning structured cablingPlanning structured cabling : :

wiring closet specificationswiring closet specifications


Overview of wiring closetOverview of wiring closet

- Selection of wiring closets (MDF/ IDF) according to standards.

One of the early decisions is:One of the early decisions is:

- MDF is where many of networking devices and cables will be installed


Cabling standardsCabling standards


• Services as a central point of a star Services as a central point of a star topology (TIA/EIA 568A standard)topology (TIA/EIA 568A standard)

• Where the horizontal cabling runs Where the horizontal cabling runs must be attachedmust be attached

• Where the patch panels and Where the patch panels and switches/ hubs must be installed.switches/ hubs must be installed.

Wiring closet specificationsWiring closet specifications::

• Must be large enough to accommodate Must be large enough to accommodate equipment and extra space for future equipment and extra space for future growth:growth:


•Each floor must have at least one wiring Each floor must have at least one wiring closetcloset•One wiring closet should be added for One wiring closet should be added for each 1000 each 1000 m2 or the horizontal cable or the horizontal cable distance exceeds 90m.distance exceeds 90m..


Environmental specificationsEnvironmental specifications

Materials for walls, floors, and Materials for walls, floors, and ceilings. ceilings.

Temperature and humidity. Temperature and humidity. Locations and types of lighting. Locations and types of lighting. Power outlets.Power outlets. Room and equipment access. Room and equipment access. Cable access and support. Cable access and support.

Selected room/ closet should satisfy certain requirements for:


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.

Rooms must not have a dropped, or false, ceiling

•Walls , floors and ceiling


- Temperature: 21- Temperature: 21oo..

- - humidity: 30 – 50%.humidity: 30 – 50%.

•VHAC

•Lighting and power outlets:

- No water or steam pipes running through or above the room.

- minimum of two dedicated, non - switched, AC duplex electrical outlets.


- 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.


•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;


Wiring hub and patch Wiring hub and patch panel were mounted to panel were mounted to a wall with a hinged a wall with a hinged wall bracket.wall bracket.

Wiring hub and patch panel were mounted with distribution rack


- 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


Wiring closet identificationWiring closet identification


- You may think of a hub as a central point of a circle which has horizontal cables radiating from it.


• In order to determine the location of wiring In order to determine the location of wiring closet begin by drawing the floor plan;closet begin by drawing the floor plan;

•Add devices that will be connected to network;Add devices that will be connected to network;

• identify secure locations to be used as MDF/IDF;identify secure locations to be used as MDF/IDF;

• MDF should be close to the POP;MDF should be close to the POP;

• determine number of wiring closets;determine number of wiring closets;


• draw circles of radius 50 m from each potential draw circles of radius 50 m from each potential wiring closet (hub location)wiring closet (hub location)

• if there are any potential wiring closets whose if there are any potential wiring closets whose catchments areas substantially overlap, you may catchments areas substantially overlap, you may eliminate one of them.eliminate one of them.

• if the catchment area does not cover all devices, if the catchment area does not cover all devices, repeaters are used (IDF).repeaters are used (IDF).


MDF location in multi-story buildingMDF 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.


MDF location in multi-building campusMDF location in multi-building campus


Backbone cabling consists ofBackbone cabling consists of::

• Backbone cabling runs•Intermediate and main cross-connects.

•Vertical media between wiring closets on different floors.•networking media between MDF and POP.•Networking media used between buildings in multi-building campus.

•Patch cords used for backbone – to –backbone cross – connection:.


Backbone cabling mediaBackbone cabling media

- 100 UTP (four – pair).

•According to TIA/EIA 568 A, four type of networking media can be Used for backbone cabling:

- 150 STP (two – pair).

- multimode optical fiber

- single mode optical fiber.


•IDF can be connected to MDF in two ways:IDF can be connected to MDF in two ways:

1. IDF can be connected directly to MDF


2. 1st IDF connected to 2nd IDF; the 2nd is then connected to MDF;


• No work areas are connected to ICC;• No more than one ICC can be passed through to reach MDF


•Maximum distance for backbone cabling:Maximum distance for backbone cabling:


Electricity and GroundingElectricity and Grounding

Institute of Technology Sligo - Dept of Computing• DC current flows in a constant value Examples: flashlight, car battery, computer motherboard


• AC noise all around us: in walls, ceilings, floors

• AC noise can come from: - from video monitors, H/D drives

•AC noise:AC noise:


•Electrostatic static discharge (ESD) 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.


•Safety ground Safety ground


• 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.


•Multi-ground connectionsMulti-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.


• 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.


• A good way to avoid current pass through the body, and through the heart, is to use one hand rule.

•Avoiding dangerous circuits between buildingsAvoiding 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.


Network power supply issuesNetwork power supply issues


•Power problem classificationPower problem classification


• 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.


•Typical Power line problems: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


- Possible solutions:

-relocate a computer to a different electrical

circuit.

- voltage regulators.

- UPS.


• Total power loss:

- cause: excessive demand on power grid.

-Lighting storms.-Ice on power lines

-Car accidents

- effects: system shutdown.

- Possible solutions:

- UPS.


• Spike:

- instantaneous increase in voltage (microseconds).

-cause: nearby lighting strike, equipment cycle

on or off.

- effect: hardware damage, lockups, data loss.

Solution:

-surge suppressors


• 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.


• Oscillation (harmonics or noise):

-unwanted electrical signal of high frequency

form other equipment (RFI, EMI).


Solution:

-shortening power cable runs.-power line filtration.

- cause: lighting, generators, radio transmitters,

-disrupts the smooth sine wave expected from

utility power.

excessively long electrical wiring run.

- effects: data loss, errors.


• 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.


1. Standby (off-line or switched) ups

Types of UPS:

2. On-line (continuous) UPS.

3. Line-interactive UPS.


Good Luck !

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