Chap 8 Design and Documentation Andres, Wen-Yuan Liao Department of Computer Science and Engineering De Lin Institute of Technology andres@dlit.edu.tw http://www.cse.dlit.edu.tw/~andres

Overview Network Design and Documentation Document brainstormed ideas, problem solving matrices Wiring closet specifications Wiring and electrical techniques used in network building

Basic Network Design and Documentation General design process Network design issues General network design process Network design documents

General design process Layer 1 design A logical and a physical topology Layer 2 LAN topology Reduce congestion and collision domain size Layer 3 topology Break up both collision and broadcast domains.

Network design issues Gather information about the organization Make a detailed analysis and assessment of the current and projected requirements Identify the resources and constraints of the organization

Network design 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, MAC addresses, and IP addresses

Wiring Closet Specifications Overview of wiring closet selection Size Environmental specification Walls, floors, and ceilings Temperature and humidity Lighting fixtures and power outlets Room and equipment access Cable access and support

Overview of wiring closet selection MDF:Main Distribution Facility/Facilities IDF:Intermediate Distribution Facilities

Size The horizontal cabling runs must be attached to a central point in a star topology The central point is the wiring closet Where the patch panel and the hub must be installed

Size TIA/EIA-569 A minimum of one wiring closet Additional wiring closets for each 1,000 m2

Environmental specification Power supply and heating/ventilation/air conditioning (HVAC) issues Be secure from unauthorized access Meet all applicable building and safety codes

Walls, floors, and ceilings Bear the load MDF: 4.8 kPA (100 lb/ft²) IDF: 2.4 kPA (50 lb/ft²) Raised floor Accommodate incoming horizontal cables Floor coverings should be tile

Temperature and humidity Maintain a room temperature of approximately 21° C No water or steam pipes running through or above the room, with the exception of a sprinkler system Relative humidity should be maintained at a level between 30%-50%

Lighting fixtures & power outlets A minimum of two dedicated, non-switched, AC duplex electrical outlet receptacles, each on separate circuits Florescent lighting should be avoided for cable pathways because of the outside interference that it generates

Room and equipment access The door of a wiring closet should be at least .9 m wide, and should swing open out of the room, thus ensuring an easy exit for workers The lock should be located on the outside

Room and equipment access Allow 48 cm for the panel to swing out from the wall A distribution rack, then it must have a minimum 15.2 cm of wall clearance for the equipment, plus another 30.5-45.5 cm for physical access by workmen and repairmen

Cable access and support If a wiring closet serves as an MDF, all cable running from it should be protected by 10.2 cm conduit or sleeved core All horizontal cabling that runs from work areas to a wiring closet should be run under a raised floor

Cable access and support Any wall/ceiling openings that provide access for the conduit, or sleeved core, must be sealed with smoke and flame-retardant materials

Identifying Potential Wiring Closets Topology as floor plan Selecting potential locations Determining number of wiring closets Identification practice

In order to determine the location of a wiring closet Topology as floor plan In order to determine the location of a wiring closet Drawing a floor plan of the building Adding to it all of the devices that will be connected to the network Computers, printers and file servers

Selecting potential locations Identify secure locations that are close to the POP The POP is where telecommunications services, provided by the telephone company, connect to the building's communication facilities

Determining number of wiring closets Use your compass to draw circles: a radius of 50 m from potential hub locations If overlap, eliminate one of the hub locations To see if one of them is closer to the POP than the other(s)

Horizontal and Backbone Cabling Catchment area problems MDF location in a multi-story building Example of where you would use multiple wiring closets Cabling for MDF and IDF connections Backbone cabling media TIA/EIA-568-A requirements for backbone cabling Maximum distances for backbone cabling

Catchment area problems If the 100 m catchment area cannot provide enough coverage, it can be extended by using repeaters 100 Ohm UTP (four pair) 150 Ohm STP-A (two pair) 2 fiber (duplex) 62.5/125 µm optical fiber Multimode optical fiber

MDF location in a multi-story building The MDF is usually located on one of the middle floors of the building The POP might be located on the first floor, or in the basement

Cabling for MDF and IDF connections Backbone cabling: vertical cabling Connect wiring closets to each other

Backbone cabling media TIA/EIA-568-A 100 Ω UTP (four-pair) 150 Ω STP-A (two-pair) 62.5/125 µm multimode optical fiber Single-mode optical fiber The IDF is sometimes referred to as the horizontal cross-connect (HCC) The MDF is sometimes referred to as the main cross-connect (MCC)

Only one

Electricity and Grounding Differences between AC and DC AC line noise Electrostatic discharge Grounding electrical current in computer equipment Purpose of grounding computer equipment Safety ground connections Safety ground connection problems

Differences between AC & DC DC flows at a constant value when circuits are turned on AC rises and falls in current values

AC line noise Coming from a nearby video monitor, or hard disk drive It does this by adding unwanted voltages to the desired signals Prevent a computer's logic gates from detecting the leading and trailing edges of the square signal waves

Electrostatic discharge ESDs can destroy semiconductors and data, in a random fashion, as they shoot through a computer A solution that can help solve problems that arise from ESD is good grounding

Grounding electrical current in computer equipment The safety ground wire is connected to any exposed metal part of the equipment The motherboards and computing circuits in computing equipment are electrically connected to the chassis This also connects them to the safety grounding wire, which is used to dissipate static electricity.

Grounding Prevent such metal parts from becoming energized with a hazardous voltage Circuit breakers and Ground Fault Circuit Interrupters (GFCIs) Surge suppressors and Uninterrupted Power Supplies (UPS) Be required to protect computing and networking equipment

Safety ground connection problems The earth ground between buildings is almost never the same

Cabling and Grounding Causes of ground potential problems Networking devices and dangerous circuits Faulty ground wiring problems Avoiding potentially dangerous circuits between buildings How fiber optic cable can prevent electrical shocks Reasons for using UTP for backbone cabling between buildings

Causes of ground potential problems When devices with different ground potentials are linked in a circuit, they can produce hazardous shocks

Networking devices and dangerous circuits The closed circuit produced by the use of UTP cable would then allow electrical current to flow from the negative source to the positive source One hand rule You should not use more than one hand at a time to touch any electrical device The second hand should remain in your pocket

Avoiding potentially dangerous circuits between buildings Use fiber-optic cable as the backbone Because glass is an insulator rather than a conductor, electricity does not travel over fiber-optic cables

Reasons for using UTP for backbone cabling between buildings Whenever copper is used for backbone cabling, it can provide a pathway for lighting strikes to enter a building

Network Power Supply Issues: Power Line Problems Power problem classifications Normal mode and common mode Typical power line problems Sources of surges and spikes Surge and spike damage Surge and spike solutions Sag and brownout solutions Oscillation solution

Power problem classifications Normal mode problem Exists between the hot and neutral wire Do not, ordinarily, pose a hazard to you or to your computer Be intercepted by a computer's power supply, an uninterruptible power supply or an AC power line filter

Power problem classifications Common mode problem If a situation involves either the hot, or neutral wire, and the safety ground wire Go directly to a computer's chassis without an intervening filter.

Typical power line problems Power disturbance Unwanted voltage that is sent to electrical equipment Include voltage surges, sags, spikes, and oscillations Another situation that can cause power problems is a total power loss

Surge A voltage increase above 110% of the normal voltage carried by a power line A few seconds Hardware damage Most computer power supplies that run at 120 V are not built to handle 260 V for any length of time

Sag/Brownout A brownout that lasts less than a second Voltage on the power line falls below 80% of the normal voltage Caused by overloaded circuits

Spike An impulse that produces a voltage overload on the power line Spikes last between .5 and 100 microseconds In simple terms, when a spike occurs it means that your power line has momentarily been struck with a powerful hit of at least 240 V

Oscillations and Noise Oscillations are also sometimes referred to as harmonics, or noise A common cause of oscillation is an excessively long electrical wiring run, which creates an antenna effect.

Sources of surges and spikes Probably the most common one is a nearby lightning strike Utility switching operations performed by the local power company can also trigger electrical surges and spikes

Sources of surges and spikes Inside your school, office, or building Elevators, photocopiers, and air conditioners, cycle on and off, they create momentary dips and surges in power

Surge and spike solutions Surge suppressors When surges or spikes come in, surge suppressors divert them to ground A good rule of thumb to follow is to protect all networking devices with surge suppressors

Surge and spike solutions If you protect one networking device with a surge suppressor, then you should protect all devices, including the telephone line, in the same way

Sag and brownout solutions Every network should have some type of uninterruptable power supply

Oscillation solution The best way to address the problem of oscillation is to rewire

Surge Suppressors and UPS Functions Surge suppressors: networking device locations Surge suppressors: for power panel locations UPS: for certain LAN devices UPS: for certain electrical problems UPS: components UPS: differences in UPS features UPS: description and operation

Surge suppressors: networking device locations Surge suppressors are usually mounted on a wall power socket, to which a networking device is connected A device called a metal oxide varistor (MOV) is most often used as this type of surge suppressor

Surge suppressors: networking device locations This type of surge suppressor has a limited lifetime, dependent, in part, on heat and usage

Surge suppressors: for power panel locations By placing a commercial grade surge suppressor near the power panel, the impact on the network, of voltage surges and spikes diverted to ground, can be reduced

UPS: for certain electrical problems An UPS is designed to handle only short-duration power outages If a LAN requires uninterrupted power, even during power outages that could last several hours, then a generator would be needed to supplement the backup provided by a UPS

UPS: components Inverter battery charger Convert low-level DC voltage of the batteries into the AC voltage, normally supplied by the power line, to networking devices battery charger Designed to keep the batteries in peak condition during periods when the power line system is functioning normally

UPS: components Batteries Generally, the bigger the batteries in a UPS, the longer a period of time it will be able to support networking devices during power outages

UPS: description and operation A good UPS should be designed to communicate with the file server Shut down files when the UPS battery power nears its end A good UPS reports instances when the server starts to run on battery power

Summary Document what you have done A wiring closet Backbone cabling Surge suppressors