1. ITNW 1325, Chapter III, Part II
Network Cables
ITNW 1325, Chapter III, Part II

2. Coaxial Cable

3. Coaxial Cable Overview:
Was the foundation of Ethernet networks in 1970s – replaced by newer twisted pair and fiber cable
Has a single or multiple copper strands at its center – protected by PVC or Teflon insulation
Protected and grounded via metallic shield (“braiding”)
Protected from physical damage by a layer of dielectric insulator (“sheath”) on the outside
Allows relatively long segments and highly resistant to noise – more expensive and less convenient to handle

4. Coaxial Cable
Overview (continued):

5. Coaxial Cable Overview (continued):
Defined by Radio Guide (RG) specifications – with few most common types in use
Classify the cores according to American Wire Gauge (AWG) numbers – the smaller is the diameter, the larger is the AWG number
Differ by materials used for the core and for shielding, the core’s diameter, impedance, attenuation, data rates, and terminators used

6. Coaxial Cable
RG-6:
Contains an 18 AWG conducting copper core with an impedance of 75 ohms – thick and not flexible
Used for delivering cable TV and Internet service over long distances to residential areas – not used for LANs

7. Coaxial Cable
RG-6 (continued):

8. Coaxial Cable RG-8 (“Thicknet”, “10Base5”):
Contains an 10 AWG conducting copper core with an impedance of 50 ohms – very thick and inconvenient
Allowed throughput up 10 Mbps with a maximum segment length of 500 m
Used within first baseband (Ethernet) data networks

9. Coaxial Cable
RG-8 (continued):

10. Coaxial Cable RG-58 (“Thinnet”, “10Base2 Cable”):
Contains a 24 AWG conducting copper core with an impedance of 50 ohms – thin and quite flexible
Allowed throughput up 10 Mbps with a maximum segment length of 185 m
Entirely replaced the 10Base5 cable within baseband data networks – popular in mid-80s and 90s

11. Coaxial Cable
RG-58 (continued):

12. Coaxial Cable
RG-59:
Contains a 20 or 22 AWG conducting copper core with an impedance of 75 ohms – thin and quite flexible
Allowed throughput up 10 Mbps with a maximum segment length of 185 m
Used for delivering video signals for short distances
Less expensive than RG-6 but suffers from attenuation

13. Coaxial Cable
RG-59 (continued):

14. Coaxial Cable Termination

15. Coaxial Cable Termination
Overview:
Necessary to avoid bouncing of the signal off the cable’s ends – accomplished by using connectors or special terminators with the same impedance as the cable used
Two common types – F-type and BNC
F-Connector:
Suitable for cables with a solid metal core – becomes the pin in the center of the connector (used in RG-6)
Mounted on a cable by crimping or compression – both male and female connectors are threaded and screw together like a nut and bolt assembly

16. Coaxial Cable Termination
F-Connector (continued):
Male Female

17. Coaxial Cable Termination
Bayonet Neill-Concelman (BNC) Connector:
Mounted on a cable by crimping, compression, or twisting – connects to another BNC connector via a turning and locking mechanism (“bayonet coupling”)
Male connector uses its own conducting pin – not the core of the cable like F-type ones
Commonly used with RG-59 cable

18. Coaxial Cable Termination
BNC Connector (continued):
Male Female

19. Coaxial Cable Termination
BNC Connector (continued):

20. Twisted Pair (TP) Cable

21. Twisted Pair Cable Overview:
Carries color-coded pairs of insulated copper wires
Wires in each pair are twisted around each other – from 1 to 4200 pairs depending on the cable type
Inexpensive, flexible, easy to install
Twist ratio – the number of twists per meter – measures resistance to crosstalk
Higher twist ratio leads to lesser crosstalk but requires more cable – increases attenuation and raises the cost

22. Twisted Pair Cable Overview (continued):
Uses a variety of twist ratios, pair numbers, copper grades, shielding types, etc.
The TIA/EIA 568 standard defines categories – CAT5, CAT6, or CAT7 TP cable is needed for modern LANs
Comes in two types – shielded and unshielded

23. Twisted Pair Cable Shielded (STP):
Shielding prevents external EM forces from distorting the signal traveling in the wires
Each pair in individually insulated and surrounded by metallic shielding
Grounded shielding enhances its protective effects
Noise, shielding material, quality, and symmetry, and grounding affect the protection provided

24. Twisted Pair Cable Unshielded (UTP):
Employs no shielding – contains insulated wire pairs encased in a plastic sheath only
Provides acceptable resistance to and less expensive than STP – widely used on computer networks

25. Twisted Pair Cable STP vs. UTP:
Provide same levels of throughput – from 10 Mbps to 10Gbps – depending on quality and type
STP is more expensive since uses more materials, is less common, and required more expensive installation due to grounding
High-grade UTP is priced similarly to mid-grade STP

26. TIA/EIA Twisted Pair Categories

27. TIA/EIA Twisted Pair Categories
Contains four wire pairs
Provides 10 Mbps throughput and 16 MHz bandwidth
Limits segment length to 100 m (330 ft)
Widely used in VoIP networks
CAT4:
Provides 10 Mbps throughput and 20 MHz bandwidth
Carries better interference protection than CAT3
Both are replaced by newer UTP categories

28. TIA/EIA Twisted Pair Categories
CAT4 (continued):

29. TIA/EIA Twisted Pair Categories
Contains four wire pairs
Provides 100 Mbps throughput and 100 MHz bandwidth
Limits the length of each segment to 100 m (330 ft)
Connects to a NIC via an RJ-45 connector
Uses 118 twists per meter (3 per inch) on average
Was produced in large quantities – still widely available
Inexpensive, effective, popular

30. TIA/EIA Twisted Pair Categories
CAT5 (continued):

31. TIA/EIA Twisted Pair Categories
A version of CAT 5 cable with high-quality copper
Contains four wire pairs
Has higher twist ratios
Incorporates better cross-talk reduction methods
Provides 350 MHz bandwidth
Allows 350/100 m segments at 100/1000 Mbps
Inexpensive – widely used within 1 Gbps networks

32. TIA/EIA Twisted Pair Categories
CAT5e (continued):

33. TIA/EIA Twisted Pair Categories
Contains four wire pairs, each wrapped in foil insulation
Additional insulation covers the bundle of four pairs
Carries fire-resistant plastic sheath on the outside
Resistant to crosstalk
250 MHz bandwidth provides up to 10 Gbps throughput
Allows 100 m (300 ft) long or 37 m (120 ft) long segments (for up to 1 Gbps or 10 Gbps, respectively)
Uses newer GG-45 connectors
Widely used in modern 1 Gbps networks

34. TIA/EIA Twisted Pair Categories
CAT6 (continued):

35. TIA/EIA Twisted Pair Categories
CAT6 (continued):

36. TIA/EIA Twisted Pair Categories
A higher-grade version of CAT6 cable
Further reduces attenuation and crosstalk
Allows longer segment lengths – up to 100 m at 10 Gbps
Provides 550 MHz bandwidth
Requires GG-45 connectors
De Facto standard on modern networks

37. TIA/EIA Twisted Pair Categories
CAT6e (continued):

38. TIA/EIA Twisted Pair Categories
Contains increased amount of shielding
Larger, heavier, less flexible
Has 600 MHz bandwidth
Provides 10 Gbps throughput on up to 100 m (330 ft) segment length, with large margin
Requires GG-45 connectors
De Facto standard on modern backbone networks
CAT7a:
In theory – 1 GHz, 40/100 Gbps at up to 50/15 m
Currently under development

39. TIA/EIA Twisted Pair Categories
CAT7 (continued):

40. TIA/EIA Twisted Pair Categories
Cost:
PCI Express NIC, single RJ-45 connector: $30–40
CAT6 50 ft patch cable: $10–12
Troubleshooting implies replacing cable

41. Twisted Pair Termination

42. Twisted Pair Termination
Overview:
Proper termination is required on both ends
Poor termination leads to a data loss or a noise
TP cable is automatically terminated when RJ-45 and GG-45 jacks are crimped onto it
Two TIA/EIA standards exist for inserting the cable into jacks – 568A and 568B
Any of the two standard can be used – the same one should be used on the entire network
TP patch cable – sold in stores as premade, terminated, tested, and packaged cable

43. Twisted Pair Termination
Termination (overview):
Green Pair #3 – Transmit Orange Pair #2 – Transmit
Orange Pair #2 – Receive Green Pair #3 – Receive

44. Twisted Pair Termination
Straight-Through:
Implies same TIA/EIA standard used on both ends
Wires aren’t twisted end-to-end
Used for connecting a PC to a hub or a switch
Crossover:
Implies using TIA/EIA 568A standard on one end and TIA/EIA 568B standard on another end
Used for connecting two workstations or two network devices directly

45. Twisted Pair Termination
Crossover (continued):

46. Making Twisted Pair Cables

47. Making Twisted Pair Cables
Tools Needed:
A wire cutter
A wire stripper (removes the sheath)
A crimping tool (fixes wires inside the connector)
May come within same device
Steps:
Make a clean cut at both ends of wire using wire cutter
Remove one inch of the sheath off of one end or wire
Make sure to not to damage insulation

48. Making Twisted Pair Cables
Steps (continued):
Separate the pairs and unwind each pair for up to ½ inch
Align the wires on a flat surface according to colors and positions
Pull steadily across the unwound section of each wire (“groom” wires)
Slide wires into their positions in the RJ-45 plug
Place the RJ-45 plug in the crimping tool and press firmly avoiding any rotation
Use tester to verify transmission over the wire made

49. Fiber Optic Cable

50. Fiber Optic Cable Layered Structure:
Inner core – glass or plastic fibers at the center that carry laser pulses or an LED light used for data transmission
Cladding – a layer of plastic or glass around the fibers that reflects the light back to the core
Plastic buffer – an opaque layer that protects the cladding and the core and absorbs any light that escapes
Strands of Kevlar – a polymeric fiber that surrounds the plastic buffer and prevents stretching and damaging
Plastic sheath – providing the overall cable protection

51. Fiber Optic Cable
Layered Structure (continued):

52. Fiber Optic Cable Single-Mode Fiber (SMF):
Uses narrow core – less than 10 microns in diameter
Propagates light without reflections – causes no dispersion and no significant energy loss
Provides the highest bandwidth of all media and allows the longest distance without requiring repeaters
Allows 60 km (37 mi) long segments at 10 Gbps
Good for connecting large networks together
The most expensive networking medium
Suitable for WANs

53. Fiber Optic Cable
Single-Mode Fiber (continued):

54. Fiber Optic Cable Multi-Mode Fiber (MMF):
Uses wider core – from 50 to 115 microns in diameter, with 62.5 microns being most common size
Multiple laser or LED pulses are sent over the fiber at different angles
Allows 300 m (910 ft) long segments at 10 Gbps, 550 m (1670 ft) at 1 Gbps, and 2 km (6060 ft) at 100 Mbps
Used for connecting network devices to a backbone
Suitable for both LANs and WANs

55. Fiber Optic Cable
SMF vs. MMF:

56. Fiber Optic Cable MMF vs. Copper, Advantages:
Allows longest distances without requiring repeaters
Much more resistant to noise
Very secure – tapping into light transmissions isn’t easy
MMF vs. Copper, Disadvantages:
Installation and field repairs are much more complex for MMF (requires special equipment)
Much more expensive
MMF is used to provide much higher throughput – not anymore (CAT7 TP cable – up to 10 Gbps)

57. Fiber Optic Cable Characteristics:
Highest throughput – no resistance allows achieving 100 Gbps per channel and reduces errors
Highest cost – most expensive medium, NICs, and hubs, plus the highest installation costs – not practical for small networks
Best EMI and noise immunity – no current used
Size and scalability – segment length is limited by degradation of the signal (“optical loss”), with typical values from 150 to 40,000 meters (455 to 121,200 ft)
Imperfections at connection points affect segment length

58. Fiber Optic Cable Connectors:
Ten different types exist, with four being being most common – Straight Tip (ST), Standard Connector (SC), Local Connector (LC), and Mechanical Transfer Registered Jack (MT-RJ)
All can be used for both SMF and MMF
ST and SC are used on older networks
LC and MT-RJ are smaller in size – allow higher density at termination points, used in newer networks
MT-RJ connector contains two strands of fiber in a short protective tube (“ferrule”), allowing full-duplex mode

59. Fiber Optic Cable
Connectors (continued):
ST connector SC connector

60. Fiber Optic Cable
Connectors (continued):
LC connector MT-RJ connector

61. Fiber Optic Cable
Connectors (continued):

62. Fiber Optic Cable Cost: PCI Express NIC, single LC connector: $500–600
MMF 50 ft cable, LC connecter: $50 – 60
Troubleshooting implies using professional services
Installation time and labor costs are much higher than for TP cable

63. Homework
Read the chapter and the summary section, then review the key terms learned
Answer the review questions and verify your answers with the chapter or lecture slides
Complete the case projects 3-1 and 3-3