1. DCN286 INTRODUCTION TO DATA COMMUNICATION TECHNOLOGY
Network Physical Layer
Connection

2. Purpose of Physical Layer
The role of the OSI physical layer is to encode the binary digits that represent data link layer frames into signals and to transmit and receive these signals across the physical media---- cooper wires, optical fiber, and wireless that connect network devices.

3. Network Access Layer
The network access layer is concerned with all of the issues that an IP packet requires to actually make a physical link to the network media.
It includes the LAN and WAN technology details, and all the details contained in the OSI physical and data link layers.

4. Popular Copper Media Standards
TIA (Telecommunications Industry Association) and EIA (Electronic Industries Alliance) work together to publish commercial building telecommunications cabling standards TIA/EIA-568-B which defines how to use the pins on the connectors on the ends of the cables.
IEEE (Institute of Electrical and Electronic Engineers) publishes LAN standards such as IEEE802.3 which will define cable requirement.
Cabling standards are from TIA/EIA. But, the predefined cable would be selected in various Ethernet environments. For instance, coaxial calb ewould be used in 10BASE2 and 10BASE5. UTP (Unshielded Twisted Pair) cable would be used in 10BASE-T, 100BASE-T and 1000BASE-T.

5. Coaxial cable Gradually outdated from LAN
Can run for longer distances than either STP or UTP
Less expensive than fiber-optic cable though it is expensive than STP or UTP
Still popular for TV and home internet service
10BASE2 (Thinnet)
10BASE5 (Thicknet)

6. STP (Shielded Twisted Pair) cable
Shielding provides better electrical signals by reducing noise and attenuation.
Shielding makes the cable more expensive, heavier and hard to bend.
In general, the STP connector could be RJ45. But, it can be others. I would not test you other connector name in this class. So, you are correct to say that the STP connector is RJ45.

7. UTP (Unshielded Twisted Pair)
Flexible and easy install
Offer the same data speeds
Inexpensive
RJ45 connector (RJ11 is for phone cable).
It can be used to offer speed, 10Mbps, 100Mbps, 1000Mbps (1Gbps), and 10Gbps. It is possible to use RJ45 for phone line connection. The only thing you need to remember is to connect the right wire pair to the connector.

8. UTP Implementation

9. UTP Implementation Straight-through Cable Cross-over Cable
Switch to Router
Switch to PC or Server
Hub to PC or Server
Cross-over Cable
Switch to Switch; Switch to Hub; Hub to Hub
Router to Router; PC to PC; Router to PC
Roll-over Cable (Configuration Purposes)
PC to Router; PC to Switch

10. UTP Implementation Straight-Through cable
A cable that maintains the pin connection all the way through the cable.
Cat 5 and Cat5e: Only wires 1, 2, 3, and 6 are used
Gigabit Ethernet uses all the wires
To connect devices such as PC or routers to other devices as hub or switches.

11. UTP Implementation Cross-over cable
A cable that crosses the critical pair to properly align, transmit, and receive signals on the device with line connections
Pin 1 at one end and Pin 3 at the other end
Pin 2 at one end and Pin 6 at the other end
Used to connect similar devices:
Switch to switch
Hub to hub

12. TIA/EIA568-A and B pin outs
Function
568A wire color
568 B wire color 1
TD+
White/Green
White/Orange 2
TD-
Green
Orange 3
RD+ 4
Unused
Blue 5
White/Blue 6
RD- 7
White/Brown 8
Brown
It is good to practice making Ethernet cables. In general, you should always test the hand-made cables and try not to use them if commercial cables are available.

13. Straight through cable
Can be used to connect PC and other network equipments to LAN hub/switch
Wire 1 and 2 are used to transmit data
Wire 3 and 6 are used to receive data
If you look at wires in the connector on both ends, the sequence must be same. That is the way to identify if the cable is straight through, cross-over and roll-over.
If wire 1 and 2 are orange/white and orange, what would your wire 3 and 6 color?
On another end of the straight-through cable, what would be wire 1 and 2 color?

14. Cross-over cable
It is used to connect two same equipments such as PC-to-PC.
Both ends need to send data on pin 1 and 2; receive data on pin 3 and 6.
In 568B, one end has white/orange and orange on pin 1 and 2; another has white/orange and orange on pin 3 and 6.
In 568B, one end has white/green and green on pin 3 and 6; another end has them on pin 1 and 2.
Cable tester can easily tell. If you are unable to check the color, to use the cable connecting one laptop to another desktop can identify if it is straight through or cross-over.
If wire 1 and 2 are green/white and green, what would your wire 3 and 6 color?
On another end of the cross-over cable, what would be wire 1 and 2 color?

15. Rollover cable Usually used as console cable.
Change the sequence on another end.
If wire 1 and 2 are orange/white and orange, what would your wire 3 and 6 color?
On another end of the roll-over cable, what would be wire 1 and 2 color?

16. Rollover or Console Cable
The cable used between a terminal and a console port is a rollover cable with RJ-45 connectors.
Rollover cable (or Console cable) has a different pinout than the straight-through or crossover cable.
The pinout for a rollover cable is:
1 to 8, 2 to 7, 3 to 6, 4 to 5, 5 to 4, 6 to 3, 7 to 2, and 8 to 1.

17. Connector and Adapter
The 8 Position 8 Contact (8P8C) (often called RJ45) connector
Cross over adapter
The 8 Position 8 Contact (8P8C) (often called RJ45) connector is used on both end of ethernet cables.

18. Optic media
Fiber-optic cable has the strongest ability to resist EMI (electromagnetic interference), RFI (Radio Frequency Interference)
Fiber’s bandwidth is much higher than any other media.
Fiber is highly secure and it is easy to detect intrusion.
Fiber uses light signal transmission and its attenuation is much less than electrical signals. Its length could be very long
An optical fiber (or fibre) is a glass or plastic fiber that carries light along its length.
No any electricity in the optic cable!!!

19. Optical fiber cable components
Core: usually made by silicon dioxide (from sand)
Cladding: coated on the core to reflect light and seal it inside
Buffer: physical protect cladding and core
Jacket: prevent damage from abrasion, solvents and other contaminants
Strengthening material was introduced in the text book. But, it is often used in multimode cables.

20. Optical Fiber Connector (Optional)
LC/PC connector and SC/PC connectors have caps covering the ferrules
Other connectors are ST, SC, MT, MT-RJ, MU, etc, etc

21. Multimode fiber
Fiber with large (greater than 10 μm) core diameter may allow light coming in with different angles. (It must be in limit of acceptance cone)
Optical fiber cable main transmitter types are LED and laser. LED is usually for short-distance light transmission.

22. Single mode fiber
Fiber with a core diameter less than about ten times the wavelength of the propagating light and it can only allow light coming in from one direction.

23. LAN Connectivity Devices
Repeaters
Hubs
Switches
Bridges
Routers

24. Repeaters
A repeater can be used to increase the length of your network by eliminating the effect of attenuation on the signal.
It connects two segments of the same network, overcoming the distance limitations of the transmission media.
Some repeaters also serve as transmission media adapters, connecting two different types of media.

25. Repeaters
Repeaters can connect segments that have the same access method. (CSMA/CD, Token Passing, Polling, etc.)
Disadvantages
Repeaters do not filter data
Its use is inappropriate when there is a heavy network traffic.

26. Repeater 10base5 – 500meter cable length limit;
10BaseT - 100meter cable length limit;
Repeater is to amplify signal and extend the cabling distance.
Working in layer 1 (Physical) of TCP/IP model
The repeater regenerates the signal.

27. Repeaters
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Figure11-6

28. Hub Central connection of Ethernet LAN.
Physically Star topology and could be logically RING, Bus and/or Star
May have built-in repeater
Working in layer 1 (Physical) of TCP/IP model
Hub is an outdated device already. It is replaced by switch already.

29. Hubs
A hub is used as a central point of connection among media segments.
Cables from network devices plug in to the ports on the hub.
Hubs are referred as Concentrators or multi-port repeater
Hubs receive signals from connected devices and transmit them to the other connected devices

30. Hubs Regenerate and repeat signals
Propagate signals through the network
Can not filter network traffic
Can not determine the best path
Are used as network concentration points.

31. Hubs

32. Types of Hubs
Passive Hubs
Active Hubs
Intelligent Hubs (Switches)

33. Passive Hub It functions only as a connection point for the signals
The signal pass through a passive hub without regeneration or amplification.

34. Active Hub
It regenerates or amplifies the signal before they are retransmitted.
Drawback:
The noise is also regenerated

35. Switch
Think switch as a hub with bridge functioning on each port (interface):
Switch will offer central connection to all hosts.
Switch will only forward frame according to destination MAC address on per-port base.
Will regenerate signals (repeater function)
Most switches are working in layer 2 (Data Link) of TCP/IP model.
There are different switches. Modern high end switch could be network manageable and IT technician can remote control/configure/monitor the switch.

36. Switches

37. Forwarding Frame based on Destination MAC Address
The switch maintain table, called a MAC table, that maps destination MAC addresses with ports used to connect to each node. For each incoming frame, the destination MAC address in the frame header is compared to the list of addresses in the MAC table. If a match is found, the port number in the table that is paired with MAC address is used as exit port for the frame.
The MAC table can be referred to by many different name. It also called Switch table or Bridge table.

38. Switch Operation
To accomplish Frame Forwarding, Ethernet LAN switches use five basic operations: Learning: The Mac table must be populated with MAC addresses and their corresponding ports. The learning process allows these mappings to be dynamically acquired during normal operation. Aging: The entries in the MAC table acquired by the learning process are time stamped. This time stamp is used as a means for removing old

39. Continues Slide-37
entries in the MAC table. After it is made in the MAC table, a procedure begins count down, once it reaches count 0, the entry is aged out and remove from the table. Flooding: If a switch does not have a MAC address entry in its MAC table that matches the destination MAC address of received frame, the switch will flood the frame. Flooding involves sending a frame to all ports except the port on which the frame arrived.

40. Switch Continues
Selective Forwarding: Selective forwarding is the process of examining the destination MAC address of a frame and forwarding it out to the appropriate port. Filtering: In some cases, a frame is not forwarded. This process is called frame filtering e.g. a switch does not forward a frame to the same port on which it arrived. A switch will also drop a corrupt frame. If a frame fails a CRC check, the frame is dropped.

41. Ethernet Bridge
Intelligent device to forward frame according to destination Media Access Control (MAC) address
Forwarding: If the destination MAC address has a port different to the originate port, the frame will be sent.
Filtering: If the destination MAC address is reachable with the same interface when it arrived, the frame will be discarded.
Working in layer 2 (Data Link) of TCP/IP model
The source and destination MAC address could be a part of header info of Ethernet Frame.

42. Layer 2 Bridging

43. Bridges

44. Router
Redirect packets according to destination logical address (IP address).
Can build routing path between different network segments (subnets)
Can act as firewall
Can work as VPN (server) connection
Working in layer 3 (Network) of TCP/IP model
You can search internet to find certain router manufacturer information. Cisco, 3com, Juniper, HP, LinkSys and Dlink, etc, etc.

45. Routers
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Figure 11-7

47. Wireless tech introduction
Infrared
Bluetooth
Microwave
Radio
Wi-Fi
In general, wireless network is secondary because of two concerns: speed and security. But, it does offer mobility and convenience.
Many samples could be found in your life: cell phone, satellite TV, Bluetooth head-set, wireless mouse and keyboard, car remote access, remote control toy such as racing cars, wireless scanner, etc, etc.
Wireless operations permits services, such as long range communications, that are impossible or impractical to implement with the use of wires. The term is commonly used in the telecommunications industry to refer to telecommunications systems (e.g., radio transmitters and receivers, remote controls, computer networks, network terminals, etc.) which use some form of energy (e.g. radio frequency (RF), infrared light, laser light, visible light, acoustic energy, etc.) to transfer information without the use of wires.
-- from

48. Wireless Networking Media
Radio frequency (RF)
Laser
Infrared (IR)
Satellite/Microwaves
Wireless transmission techniques to carry wireless signals
Wireless signals are electromagnetic waves that travel through the air.

49. Wireless Networking Media
Infrared
Line of sight
Short distances
No obstacles between transmitter and receiver
Radiofrequency
Allows devices to be in different room or even buildings
Limited radio
Can be single or multiple (Spread spectrum) frequencies

50. Single Frequency
Is subject to outside interference and geographic obstructions
Insecure (Easily monitored by others)

51. Spread Spectrum
Multiple frequencies
More secure

52. Security in the Wireless Environment
The first level of security in a wireless LAN consists of protecting the radio frequency waveform itself.

53. Security in the Wireless Environment
Wireless Access Points
Wireless Bridges
Encryption
WEP – Wireless Equivalence Privacy
EAP – Extensible Authentication Protocol (IEEE 802.1X)

54. Wireless LAN Topology

55. Wireless Bridges

56. Wireless Security
If you think someone might eavesdrop on your LAN radio links…..
Encryption is the key

57. Wireless Security Approaches
WEP – Wired Equivalency Privacy
IEEE 802.1X or Extensible Authentication Protocol (EAP)

58. Wireless Equivalent Privacy
WEP
It is a security mechanism defined with the IEEE standard.
Designed to protect over the over-the-air transmissions between wireless LAN access points and NICs.
IEEE b requires 40-bit encryption keys
Cisco supports the optional 128-bit standard.

59. WEP Goals
Deny access to the network by unauthorized users who do not possess the appropriate WEP key.
Prevent the decoding of captured WLAN traffic hat is WEP-encrypted without the possession of the WEP key.
Should be supplemented with additional higher-level security mechanisms such as VPNs or Firewalls.

60. 802.1X/EAP Extensible Authentication Protocol
It is an alternative WLAN security approach to WEP
802.1X/EAP focuses on providing:
Centralized authentication
Dynamic key distribution
It is a standard for port-based network access control

61. Cabling the WAN Wide Area Network (WAN) Services
To connect one network to a remote network
Provide different connection methods
Different cabling standards from those of LANs

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