Sem 1v2 Chapter 8: Design and Documentation

1. Sem 1v2 Chapter 8: Design and Documentation

2. Your network design could take into consideration many technologies (e.g. token-ring, FDDI, and Ethernet), • Once you have settled on Ethernet, you must develop a Layer 1 LAN topology. • You must determine the type of cable, and the physical (wiring) topology that you will use. • The most common choice is CAT 5 UTP as the media, and an extended star topology as the physical (wiring) topology. • Then you must decide on which one, of the several types of Ethernet topologies, you need to use. Two common types of Ethernet are 10Base-T and 100Base-TX (Fast Ethernet). • You might use hubs, repeaters, and transceivers in your design, along with other Layer 1 components such as plugs, cable, jacks, and patch panels. • To finish Layer 1 design, you must generate both a logical and a physical topology.

3. The next step is to develop a Layer 2 LAN topology. • You could add switches to reduce congestion and collision domain size. In the future, you may be able to afford to replace hubs with switches, and more less intelligent Layer 1 devices with more intelligent Layer 2 devices. • The next step, then, is to develop a Layer 3 topology; • You could use routers to build scalable internetworks (larger LANs, WANs, networks of networks), or to impose logical structure on the network you are designing, or use them for segmentation Your network design should also consider the placement of such things as file servers, databases, and other shared resources, as well as the LAN's link to WANs and to the Internet. • Finally, you should document your network design's physical and logical topologies.

4. There are three key aspects to the "Dartmouth method” design process. First, there is the problem solving cycle, which consists of: Original problem statement. Redefine problem. Develop general specifications. Brainstorm alternatives. Select most viable alternative. Check problem definition. Redefine and add specifications. Brainstorm again if necessary. Reiterate until problem is appropriate. The second key aspect to their approach is the problem-solving matrix. This is a graphical organizer; Simply list alternatives (choices) down the horizontal rows; list specifications across the vertical columns. A third key aspect of design is brainstorming by brainstorming we mean a special 2 to 10 minute session which follows these rules: 1. quantity of ideas 2. no censorship of ideas 3. building upon others ideas 4. wildest ideas possible

5. Explain how to start designing a network. • For a LAN to be effective and serve the needs of its users, it should be implemented according to a planned series of systematic steps. • Your first step in the process is to gather information about the organization. This information should include: • organization's history and current status • projected growth • operating policies and management • procedures • office systems and procedures • viewpoints of the people who will be using the LAN

6. The second step is to make a detailed analysis and assessment of the current and projected requirements of those people who will be using the network. • The third step is to identify the resources and constraints of the organization. Organization resources that can affect the implementation of a new LAN system fall into two main categories - computer hardware and software resources, and human resources. • The questions you ask should include: • What financial resources does the organization have available? • How are these resources currently linked and shared? • How many people will be using the network? • What are the computer skill levels of the network users? • What are their attitudes toward computers and computer applications? • Following these steps, and documenting the information, will help you estimate costs and develop a budget for the implementation of a LAN. • The final step is to document the information in the framework of a formal report.

7. Explain a general network design process. • In technical fields the design process includes: • designer - person doing the design • client - person who has requested, and is probably paying forthe design • user(s) - person(s) who will be using the product • brainstorming - generation of creative ideas for the design • specifications development - usually numbers which will measure how well the design works • building and testing - to meets client objectives and satisfies certain standards

8. Describe the documents that are required for a network design. • The following list includes some of the documentation that you should create as you design a network: • 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

9. Give an overview of wiring closet selection, MDF/IDF selection, and power supply issues. There are standards governing MDFs and IDFs, and you will learn some of these standards while learning how to select the network wiring closet(s) Finally, there are issues regarding how the AC power from the electric power company can have negative effects on our network.

10. Describe the proper size for a wiring closet. EIA/TIA 568-A specifies that, in an Ethernet LAN, the horizontal cabling runs must be attached to a central point in a star topology. The central point is the wiring closet. The size of the closet will vary with the size of the LAN, and the types of equipment required to operate it. the size of the closet will vary with the size of the LAN, and the types of equipment required to operate it.

11. Describe the environmental specifications for a wiring closet. • Any location that is selected for a wiring closet must satisfy certain environmental requirements, which include power supply and HVAC (heating/ventilation/air conditioning) issues. • The location must be secure from unauthorized access, and must meet all applicable building and safety codes. • materials for walls, floors, and ceilings • temperature and humidity • locations and types of lighting • power outlets • room and equipment access • cable access and support.

12. Describe the specifications that apply to walls, floors, and ceilings. All interior walls, or at least those on which equipment is mounted, should be covered with ¾" plywood that is raised a minimum of 1 ¾" from the underlying wall. The main distribution facility for the building, then the telephone point of presence (POP), may also be located inside the room. Minimum of 15' of wall space provided for the terminations and related equipment. Fire retardant paint must be used on the walls. Rooms selected for wiring closets must not have a dropped, or false, ceiling. The MDF required equipment, with a minimum capability of 250 lbs. per sq. foot. Where the wiring closet serves as an intermediate distribution facility (IDF), the floor must be able to bear a minimum load of 100 lb. per sq. foot. The room should have a raised floor. Floor coverings should be tile, or some other type of finished surface.

13. 8.2.1.4. Describe the specified standards for temperature and humidity levels. There should be no water or steam pipes running through or above the room, with the exception of a sprinkler system, which may be required by local fire codes. Relative humidity should be maintained at a level between 30% and 50%. The wiring closet should include sufficient HVAC to maintain a room temperature of approximately 70 ° Fahrenheit.

14. 8.2.1.5. Describe the requirements for lighting fixtures and power outlets. A wall switch should be placed immediately inside the door. Fluorescent lighting should be avoided because of the outside interference that it generates. If there is only one wiring closet in a building, or if the closet serves as the main distribution facility, there should be at least one duplex power outlet positioned every 10’ along each wall of the room. If the wiring closet serves as an IDF, then there should be at least two duplex power outlets located along each wall.

15. 8.2.1.6. Describe the requirements for room and equipment access. The door of a wiring closet should be at least 3' wide, and should swing open out of the room, The lock should be located on the outside of the door, but allow anyone who is on the inside to exit at any time. A wiring hub and patch panel may be mounted to a wall with a hinged wall bracket, or with a distribution rack. If the choice is a distribution rack, then it must have a minimum 6" of wall clearance for the equipment, plus another 12"-18" for physical access by workmen and repairmen. A 22" floor plate, used to mount the distribution rack, Full equipment cabinet, they require at least 30" of clearance in front, in order for the door to swing open. Typically, such equipment cabinets are 72" high, 29" wide, and 26" deep.

16. Design and Documentation 8.2.1.7. Describe the specifications for cable access and support. If a wiring closet serves as a MDF or IDF, all cable running to it or from should be protected by 4" conduit or sleeved core. A minimum of two excess sleeved cores or conduits should be kept in each wiring closet. All conduit and sleeved core should be kept to within 6" of the walls. All horizontal cabling that runs should be run under a raised floor. The cabling should be run through 4" sleeves that are placed above door level. In order to ensure proper support, the cable should run from the sleeve directly onto a 12" ladder rack in the room. Conduit, or sleeved core, must be sealed with smoke and flame retardant materials that meet all applicable codes.

17. Describe the first step in locating a wiring closet for an Ethernet star topology. The first step in locating a wiring closet is to obtain, or create, to-scale floor-plans of the area the network will service.Locating all the deices that will be connected to the network.

18. 8.2.2.2. Describe how to select potential locations for wiring closets. A good place for a potential wiring closet location is to identify secure locations that are close to the POP, that can serve as the main distribution facility. The POP is where telecommunications facilities, provided by the telephone company connect to the building's communication facilities, it is essential that the hub be located near it in order to facilitate wide area networking and connection to the Internet.

19. 8.2.2.3. Describe how to determine the necessary number of wiring closets. LANS that cover a large geographic area may need more than one wiring closet. When this occurs, one wiring closet must be designated as the main distribution facility (MDF). Any additional wiring closets are referred to as intermediate distribution facilities (IDFs). After you have drawn in all of the devices that are to be connected to your network, on a floor plan, The next step is to determine how many wiring closets you will need to serve the area covered by the network. You will use your site map to do this. Use your compass to draw circles that represent a radius of 50 m. Each of the network devices you depicted on your floor plan should fall within one such circle. Overlap of circles may remove a catchment area. Are there any potential hub locations whose catchment areas can contain all of the devices that are to be connected to the network

20. 8.2.2.4. Perform potential wiring closet identification: Describe your task. Answer the following questions: 1. Do any of the circles overlap? 2. Can any of the potential wiring closet locations be eliminated? 3. Do any of the circles provide coverage for all of the devices that will be connected to the network? 4. Which of the potential wiring closet locations seems to be the best? 5. Are there any circles where only a few of the devices fall outside the catchment area? 6. Which potential wiring closet is closest to the POP? 7. Based on your findings, list the three best possible locations for wiring closets. 8. Based on your findings, how many wiring closets do you believe will be required for this network?

21. 8.2.3.1. Describe the building in which you will install the LAN. The building in which you will install the LAN will provide work stations for 71 workers, and will include seven printers. The description of the building is as follows: The building occupies 7,200 sq. ft. of office space, all on a single floor. The building is 60' wide x 120' long. The ceiling height in all rooms, unless otherwise specified, is 12'. All ceilings are dropped ceilings, unless otherwise specified. All floors are poured concrete covered with industrial carpet, unless otherwise specified. All heating and cooling in the building is supplied by a forced air system..

22. 8.2.3.2. Describe the potential of wiring closet "A". 8.2.3.3. Describe the potential of wiring closet "B". 8.2.3.4. Describe the potential of wiring closet "C". 8.2.3.5. Describe the potential of wiring closet "D". 8.2.3.6. Describe the potential of wiring closet "E". 8.2.3.7. Describe the potential of wiring closet "F". 8.2.3.8. Describe the potential of wiring closet "G" 8.2.3.9. Describe the potential of wiring closet "H" 8.2.3.10. Describe the potential of wiring closet "I". 8.2.3.11. Describe the potential of wiring closet "J".

23. 8.3.1.1. Describe what happens when the catchment area of a wiring closet is not large enough. Unlike the prior example for choosing a wiring closet, many buildings will require cable runs greater that 100 meters. This necessitates the use of repeaters, or multi-port repeaters called hubs, and the use of IDFs. Emphasize to the students that these requirements are a matter of both technology (the network will not work properly if the rules are violated) and standards (networks must be built according to various standards). EIA/TIA-568 specifies the use of CAT 5 UTP for all horizontal cabling, when an Ethernet LAN uses a simple star topology.

24. 8.3.1.2. Describe the location of the MDF in a multi-story building. Typically, the main hub, of an extended star topology Ethernet LAN, is centrally located. So important is this central location, that in a high rise building, the MDF is usually located on one of the middle floors of the building, even though the POP might be located on the first floor, or in the basement. Backbone cabling (red lines) connects the POP to the MDF. Backbone cabling is also used to connect the MDF to the IDFs Horizontal cabling runs (blue lines) radiate out from the IDFs on each floor,

25. 8.3.1.3. Name another example of where you would use multiple wiring closets. Another example of a LAN, that would probably require more than one wiring closet, would a multi-building campus.

26. 8.3.1.4. Describe the type of cabling that connects the IDFs to the MDF. The IDF to MDF connections are called "backbone" cabling. There are specific EIA/TIA-568 standards The type of cabling that EIA/TIA-568 specifies for connecting wiring closets to each other is called backbone cabling. Sometimes you may see backbone cabling referrred to as vertical cabling. Backbone cabling consists of the following: backbone cabling runs intermediate and main cross-connects mechanical terminations patch cords used for backbone-to-backbone cross-connection vertical networking media between wiring closets on different floors networking media between the MDF and the POP networking media used between buildings in a multi-building campus

27. Describe the type of networking media that you would use for backbone cabling. Acceptable choices for backbone cabling are UTP or optical fiber. Most backbones installed today use optical fiber, for its immunity to EMI/RFI, lack of grounding problems, extremely long cable runs, and extremely high bandwidth. EIA/TIA-568 specifies four types of networking media that can be used for backbone cabling. These include: 100 Ohm UTP 150 Ohm UTP 62.5/125 µ optical fiber single-mode optical fiber Although EIA/TIA-568 recognizes 50 W coaxial cable, generally, it is not recommended for new installations. Most installations today use the 62.5/125 µ fiber-optic cable, as a matter of course, for backbone cabling.

28. Explain how EIA/TIA-568 requirements for backbone cabling impact the topology. Three more acronyms --are introduced in the context of the EIA/TIA-568 standards. MCC (Main Cross Connect) ICC (Intermediate Cross Connect) HCC (horizontal cross connect) The topology that is used is the extended star topology. Because more complex equipment is located at the most central point in an extended star topology, sometimes it is referred to as a hierarchical star topology.

29. There are two ways in which an intermediate distribution facility can be connected to the main distribution facility. In the first, each intermediate distribution facility can be connected directly to the main distribution facility. In this case, because the IDF is where the horizontal cabling connects to a patch panel in the wiring closet, whose backbone cabling then connects to the hub in the main distribution facility, the IDF is sometimes referred to as the horizontal cross-connect (HCC). The main distribution facility is sometimes referred to as the main cross-connect (MCC), because it connects the backbone cabling of the LAN to the Internet.

30. A second method of connecting an IDF to the central hub uses a "first" IDF interconnected to a "second" IDF. The "second" IDF is then connected to the MDF. In such instances, the IDF that connects to the work areas is called the horizontal cross-connect, and the IDF which connects the horizontal cross-connect to the MDF is called the intermediate cross-connect (ICC). Note that no work areas or horizontal wiring connects to the intermediate cross-connect when this type of hierarchical star topology is used. EIA/TIA-568 specifies that no more than one intermediate cross-connect can be passed through to reach the main cross-connect.

31. Describe the EIA/TIA-568 specifications for maximum distances of backbone cabling. The maximum backbone lengths for single-mode optical fiber (3000m), multimode optical fiber (2500m), and UTP (90m) are presented. Note the 3km distance of optical fiber allows it to be used in a area greater than many high school and junior college campuses.

32. 8.3.2.1. Explain the difference between AC and DC. The rise and fall of the current values in AC. The current value remains constant in DC.

33. 8.3.2.2. Describe how AC line noise creates a problem. One of the ways AC power line noise creates problems is by coupling into the media and distorting digital signals. Other forms of noise also cause problems on the networking medium. You will discover as you work with networks, that AC line noise, coming from a nearby video monitor, or hard disk drive, can be enough to create errors in a computer system. It does this by burying the desired signals and preventing a computer's logic gates from detecting the leading and trailing edges of the square signal waves. This problem can be further compounded when a computer has a poor ground connection.

34. 8.3.2.3. Explain how electrostatic discharge can create problems. If students are to be installing NICs or RAM they should be particularly aware of the potential problem of ESD (ElectroStatic Discharge). You know from experience, that such ESDs can sting momentarily, but in the case of a computer such shocks can be disastrous. ESDs can destroy semiconductors, and data, in a random fashion, as they shoot through a computer. One solution to prevent electrostatic discharge, is good grounding.

35. 8.3.2.4. Describe how to ground electrical current in computer equipment. For both alternating (AC) and direct current (DC) electrical systems, the flow of electrons is always from a negatively charged source to a positively charged source. Conductors Insulators. The safety ground wire is always connected to any exposed metal parts of the equipment. In computer equipment, motherboards and computing circuits are electrically connected to the chassis, and therefore to the safety grounding wire. This ground is used to dissipate static electricity.

36. 8.3.2.5. Explain the purpose of grounding computer equipment. The purpose of connecting the safety ground to the exposed metal parts of the computing equipment is to prevent such metal parts from becoming energized with a hazardous voltage that may occur as a result of a wiring fault inside the device. 8.3.2.6. Describe, and explain the function of, the safety ground connection. What should be emphasized here is that electricity presents a hazard to a person should that person become part of an electrical circuit. Human beings conduct electricity, and if they should accidentally become part of a live electrical circuit, they can be harmed. The purpose of safety ground connections is to hopefully form a different circuit, of less resistance the unfortunate human, so that electron take the path of least resistance (to ground) and not through the human's body.

37. 8.3.2.7. Describe the types of situations in which a safetyground connection would not be sufficient. The interesting situation of multiple grounds is introduced. Although the complete theory of how this occurs is beyond the scope of the class, there are a few key features to note. Ground is our reference voltage, that which we call zero volts. All voltages are measurements from one point relative to another; typically relative to ground since that is our chosen reference point. But what happens when there is a voltage between two physically distinct areas (two buildings or two floors in a building) that we are calling ground? Well nothing would occur if no circuits where formed involving these two different grounds. However, recall we are often running long conducting copper cables around the floors of the building or between buildings to build our network. These provide ways to form complex circuits involving the different grounds and conducting human beings or conducting electronic devices.

38. 8.3.3.2. Explain how network devices, placed in separate buildings could create a dangerous circuit. The way that Cat 5 UTP (or any copper-based conductor) causes different earth grounds to be a problem is illustrated. A good way to avoid having current pass through the body, and through the heart, is to use the "one-hand" rule. Simply put, this rule says that you should not use more than one hand at a time to touch any electrical device. The second hand should remain in your pocket.

39. 8.3.3.3. Describe the problems that could arise because of faulty ground wiring. The scenario where a difference in voltage exists between the network cabling and the chassis of an electronic device is described. Again, the problem is a human becoming part of an unintended circuit. When everything works correctly, according to IEEE standards, there should be no voltage difference between the networking media and the chassis of a networking device.

40. Explain how to avoid creating potentially dangerous circuits between buildings. The use of optical fiber -- which is electrically insulating (non-conducting) -- is proposed as a way to avoid creating potentially dangerous circuits between building. Since inter-building cabling is typically backbone cabling anyway, and since today most installations choose optical fiber as their backbone medium, this requirement does not present much of a problem. 8.3.3.6. Explain other types of problems that can be facilitated by the use of UTP for backbone cabling between buildings. As if the earth ground issue wasn't enough reason to discourage the use of copper-based media between buildings, another reason is presented. Lightning strikes can more efficiently couple into buildings, their networks, and their power systems if there is a copper conductor between buildings. The lesson is to just use fiber between buildings!

41. 8.3.4.1. Describe your task for design practice. Provide a plan to network the computing devices, in all three buildings, in an Ethernet extended star topology. As you develop your networking plan, assume that two computing devices are located in each numbered room. Your plan should show each of the following: 1.location of the MDF 2.location and number of IDFs 3.identity of IDFs used as horizontal cross-connects 4.identity of IDFs used as intermediate cross-connects 5.location of all backbone cabling runs between MDF and IDFs 6.location of any backbone cabling runs between IDFs 7.location of all horizontal cabling runs from IDFs to work areas

42. 8.3.5.1. Describe the building. In order to learn how multiple earth grounds can impact a LANs wiring scheme, assume that you have been asked to prepare a wiring plan for a twenty story building. Three companies occupy the building: Company A occupies the first fifteen floors. Company B occupies the sixteenth, seventeenth, and eighteenth floors. Company C occupies the nineteenth and twentieth floors.

43. 8.4.1.1. Explain the classifications of power problems. The definitions of normal mode and common mode electrical problems are introduced. Remember that all voltages (electrical potential differences) are measured between two points, so you must define what those two points are when discussing potential voltage problems. If a situation exists between the hot and neutral wire, this is referred to as a normal mode problem. If a situation involves either the hot, or neutral wire, and the safety ground wire, it is referred to as a common mode problem.

44. 8.4.1.2. Explain which is the greater hazard to safety and data, normal mode or common mode. Common mode problems are identified as the more serious of the two types of power connection problems because they go directly to the computer chassis.

45. 8.4.1.3. Describe some typical power line problems. Surge A surge is a voltage increase above 110% of the normal voltage carried by a power line. Sag A sag is a brownout that lasts less than a second. These incidents occur when voltage on the power line falls below 80% of the normal voltage. Spike A spike is an impulse that produces a voltage overload on the power line that last between .5 and 100 microseconds. When a spike occurs it means that your power line has momentarily been struck with a powerful hit of at least 240 V. Oscillation Oscillations are also sometimes referred to as harmonics, or noise. A common cause of oscillation is an excessively long electrical wiring run

46. 8.4.1.4. Describe the sources or surges and spikes. There are numerous sources of electrical 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. Equipment such as elevators, photocopiers, and air conditioners,, cycle on and off, they create momentary dips and surges in power

47. 8.3.2.5. Explain the purpose of grounding computer equipment. The purpose of connecting the safety ground to the exposed metal parts of the computing equipment is to prevent such metal parts from becoming energized with a hazardous voltage that may occur as a result of a wiring fault inside the device.

48. 8.4.1.5. Describe the damage that can occur because of surges and spikes. A spike or a surge can wreak havoc on any type of sensitive electronic equipment. including networking devices. Consequences of electrical surges and spikes can be severe. Possibilities include lockups, loss of memory, problems in retrieving data, altered data and garbling. Some of the damage that can occur because of surges and spikes is introduced. One thing that wasn’t mentioned is actual destruction of the electronic equipment.

49. 8.4.1.6. Describe the solution(s) for the problems of surges and spikes. Surge suppressors for all devices connected to the LAN (PCs, hubs, switches, routers) are recommended as a defense against surges and spikes. As a general rule therefore, consider the telephone line to be part of the network. If one networking device is protected by a surge suppressor, then all devices, including the telephone line, should be protected in the same way.

50. 8.4.1.7. Describe the solution(s) for the problems of sags and brownouts. Uninterruptible power supplies (UPS) are presented as the solution to sags and brownouts (where the power company sine wave has too low an amplitude). A drop in AC power may cause only the faintest flicker of your electric lights, however, the same drop in power can be devastating to your data.