1. 1 Design and Documentation Honolulu Community College Cisco Academy Training Center Semester 1 Version 2.1.1

2. 2 Overview n Design of physical and logical topologies. n Documentation. n Wiring closet specifications. n Wiring and electrical techniques.

3. 3 General Design Process n 1. Select the technology (Ethernet). n 2. Develop Layer 1 LAN topology. u type of cable. u physical (wiring) topology (extended star). u Type of Ethernet. u Logical topology. n 3. Develop Layer 2 LAN topology. u Segmentation - reduce congestion & collision domain size.

4. 4 General Design Process n 4. Develop Layer 3 topology. u Implement routing to build scalable internetworks. u logical structure. u segmentation - minimize broadcast domain. n Other concerns: u Placement of servers. u LANs link to WANs and to the Internet. u document your physical and logical topologies.

5. 5 Network Design Issues n First step: gather information about the organization. u 1.organization's history and current status u 2.projected growth u 3.operating policies and management procedures u 4.office systems and procedures u 5.viewpoints of people who will be using LAN n Purpose is to identify and define any issues or problems that need to be addressed.

6. 6 Network Design Issues (cont.) n Second step: make a detailed assessment of current and projected requirements. n Third step: identify resources and constraints of the organization. u document existing computer hardware and software. u identify and define projected hardware and software needs. n Purpose: determine how much training will be required, and how many people will be needed to support the LAN.

7. 7 Network Design Issues (cont.) n These steps will allow you to estimate costs and develop a budget for the implementation of a LAN.

8. 8 Wiring Closet Selection n Most important decision is selection of MDF. u Secure location, close to POP. u POP is where telecommunications services connect to the building's communication facilities. n TIA/EIA-568-A specifies that in an Ethernet star topology, every device must be connected to the hub (in wiring closet) by horizontal cabling. n To find location(s) of wiring closet(s), begin with a floor plan of the building, indicating all devices that will be connected to the network.

9. 9 Wiring Closet Selection (cont.) n Next identify potential locations for wiring closets.

10. 10 Determing Number of Wiring Closets n Draw circles of radius 50 m from each potential wiring closet locations. n Number of wiring closets is determined by what is needed to cover the building.

11. 11 Extended Star Topology n MDF of an extended star topology Ethernet LAN is usually centrally located. n In high rise building, MDF usually located on a middle floor, even if POP is on the first floor.

12. 12 MDF - multi-building campus n MDF: a central location, close to the POP,. n IDFs are located in each building. n Note: main building also requires an IDF.

13. 13 Backbone Cabling n Cabling between wiring closets is backbone or vertical cabling. n Backbone cabling include: u MCC (main cross-connects), u ICC (intermediate cross-connects), u mechanical terminations u backbone cable runs. u Cabling between MDF and POP n Recommended backbone is 62.5/125 µm fiber- optic cable.

14. 14 Backbone Cabling (cont.) n TIA/EIA 568A specifies four types of networking media for backbone cabling:  100  UTP, 150  STP, 62.5/125 µm fiber optic, and single-mode fiber optic cable. TIA/EIA 568A recognizes 50  coaxial cable, but it is not recommended for new installations. n Recommended backbone is 62.5/125 µm fiber- optic cable (multi-mode fiber).

15. 15 MDF to IDF Cabling n MCC (main cross connect) is in MDF. u connects backbone cabling to the Internet. n HCC (horizontal cross connect) is in IDF.

16. 16 MDF to IDF - another method n ICC (intermediate cross connect) in an IDF. n No work areas or horizontal wiring connects to ICC. n HCC (horizontal cross connect) in another IDF.

17. 17 n No more than one ICC between MCC and HCC.

18. 18 Backbone Cabling Lengths n TIA/EIA 568A also specifies max lengths when ICC is used.

19. 19 Specs for Backbone Cabling n TIA/EIA 568A specifies max lengths for backbone cabling.

20. 20 Electrical Concern - Noise n AC line noise, can create errors: u adding unwanted voltages to signals. u preventing detection of leading and trailing edges of square wave signals. n Problems can be compounded with poor ground connections.

21. 21 Electrical Concern - ESD n Charges can be separated by friction, e.g. by shuffling you feet across a carpet. n Very high voltages (thousands of volts) can be generated, referred to as static electricity. n When you reach for a metal object, a spark occurs - this is current flow, as the high voltage pushes the free electrons to the metal object. n This is ESD or electro-static discharge. u can randomly damage computer chips and/or data.

22. 22 Grounding Network Equipment n AC power is supplied though a 3 prong plug. n Top 2 connectors are the power. n Other connector is safety ground (earth ground). n Any exposed metal is connected to safety ground. n Computer motherboard’s ground plane is connected to the chassis and safety ground. n Ground helps dissipate static electricity.

23. 23 Safety Ground n Purpose - to prevent exposed metal parts from becoming energized with high voltage should a wiring fault occur. n A wiring fault will cause current through the ground connection, and activate protective devices such as circuit breakers to disconnect the power.

24. 24 Safety Ground Connection Problems n Using copper media, such as UTP to connect grounds in different buildings or from different power panels can present an electrical shock hazard. n Different ground voltages can also severely damage delicate computer memory chips. n Minimize danger by using “one-hand rule”. n “One-hand Rule” - touch electrical equipment with only one hand (current will not pass across your body through your heart).

25. 25 Safety Ground Connection Problems (cont.) n TIA/EIA 568A specifications permit the use of fiber-optic cable for backbone cabling. n Fiber does not conduct electricity, eliminating the shock hazard. n Fiber-optic cable is recommended for the backbone cabling between buildings, and also for linking wiring closets on different floors. n Fiber also beneficial in areas with lightning; it will not conduct lightning strike into the building.

26. 26 Classifying Power Problems n Three connections on AC power: u Hot, neutral, and safety ground. u Power problems classified by which wires are affected. n Normal mode problems - between hot and neutral. n Common mode problems - between safety ground and either hot or neutral. n Common mode problems are more serious. n Normal mode problems are intercepted by the computer’s power supply, UPS, or AC line filter.

27. 27 Typical Power Line Problems n Power disturbance is unwanted excess energy that is sent to electrical equipment. n Typical power disturbances include: u surges u sags u spikes u oscillations.

28. 28 Typical Power Disturbances n Surge - 10% voltage increase for few secs. u Causes most hardware damage in devices, particularly hubs (sensitive low voltage lines). Spike - a momentary >100% increase in voltage for 0.5 to 100  secs (very short duration). n Sag - voltage drops below 80% of normal voltage for less than 1 sec. n Brownout - voltage below 80% of normal for greater than 1 sec. n Oscillations - AC voltage harmonics or noise, caused by excessively long wires.

29. 29 Surges and Spikes n Causes: u Lightning. u Utility company switching operations. u Cycling equipment like HVAC, elevators, copy machines. n Problems: u Altered or loss data, lockups, damage to electrical devices or electronic chips. n Addressed with surge suppressors.

30. 30 Sags and Brownouts n >20% decrease in line voltage (below 80% of normal). u Sags - short duration (<1sec). u Brownouts - longer duration (>1sec). n Can cause system crashes, and loss of data. n Solved by using an UPS (uninterruptible power supply).

31. 31 Oscillations n Can cause excessive noise and erroneous data. n Solved by rewiring, to ensure clean and direct power and ground connections.

32. 32 Effectiveness of Surge Suppressors n Individual surge suppressors - placed at wall outlet, close to networking device. n Most use a MOV, metal oxide varistor. u Capable of absorbing very large currents without damage (diverts currents to ground). n May not be very effective! n Diverting surges to ground avoids equipment damage, but can cause garbled data by changing ground voltage. n MOVs have limited lifetime; are not the best choice for network protection.

33. 33 Best Surge Suppressor n Use large commercial grade surge suppressor at the power panel. n By diverting surges to ground at the power panel you minimize effect of changing ground potentials at your networking devices.

34. 34 UPS - for problem of sags & brownouts n What devices should be supported by UPS? u Factors to consider: cost, importance of service, quality of ac line power. u Every network file server should have power backup. u Any critical devices (hubs, bridges, switches, routers) should be backed up. n UPS - for outages of short duration. n For extended periods of time, a generator is needed.

35. 35 UPS Components n Batteries - storage of electrical energy (DC). u Larger batteries (greater storage capacity); UPS can supply backup power longer. n Battery Charger - keeps batteries fully charged when ac line power is available. n Power Inverter - converts DC voltage from batteries into AC line voltage.

36. 36 UPS Operation n Basic UPS: u Monitors power line. u When line power is interrupted, UPS switches to inverter powered by batteries. u Transfer time - time UPS takes to switch over to inverter power (typically few milli-secs). n More expensive on-line UPS: u operates continuously on-line, supplying AC power from inverter. Batteries are charged from AC line voltage. u Transfer time is zero.

37. 37 Basic UPS Block Diagram n S1 & S2 normally closed, S3 & S4 normally open. n When AC voltage is lost, the inverter switches on, S1 & S2 open, and S3 & S4 close.

38. 38 On-line UPS Block Diagram n Operates continuously on-line. n Transfer time is zero.

39. 39 Intelligent UPS n Has data communications capability. n Communicates with file server, informing it when battery power is running low. n Informs workstations when a power outage has occurred.

40. 40 Summary n General design process. u Select technology (Ethernet, Token Ring, etc) u Layer 1 topology. u Layer 2 topology. u Layer 3 topology. n Network Design Issues u 1.Gather information. u 2.Analyze requirements. u 3.Identify resources and constraints. n Wiring closet specs - TIA/EIA 569. n Selecting wiring closets u MDF - secure, central location, close to POP.

41. 41 Summary (cont.) n Horizontal and Backbone Cabling. u Cat 5 UTP for horizontal cabling. u Multi-mode fiber for backbone. n Electrical concerns: u AC line noise. u ESD. u Ground problems. n Power Line Problems. u Normal mode and common mode. u Surges, spikes, sags, brownouts, oscillations. u Surges & spikes addressed with surge supressors.

42. 42 Summary (cont.) u MOV, metal-oxide varistor, found in individual surge suppressors. u Commercial grade surge suppressor, installed at the power panel, is best. n UPS u Basic and on-line. n Troubleshooting u work up through the OSI model. The End