1. Local Area Network and IP addressing

2. Primary Function of Local Area Networks
To provide access to hardware and software resources that will allow users to perform one or more of the following activities:
File serving
A large storage disk drive acts as a central storage repository
Print serving
Providing the authorization to access a particular printer, accept and queue print jobs, and providing a user access to the print queue to perform administrative duties
Video transfers
High speed LANs are capable of supporting video image and live video transfers
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3. Primary Function of Local Area Networks (continued)
To provide access to hardware and software resources that will allow users to perform one or more of the following activities (continued):
Manufacturing support
LANs can support manufacturing and industrial environments
Academic support
In classrooms, labs, and wireless
support
Interconnection between multiple systems
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4. Primary Function of Local Area Networks (continued)
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5. Medium Access Control Protocols
How does a workstation get its data onto the LAN medium?
A medium access control protocol is the software that allows workstations to “take turns” at transmitting data
Two basic categories:
Contention-based protocols (statistical)
Round-robin protocols (Deterministic)
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6. Contention-Based Protocols
Essentially first-come, first-served
Most common example is carrier sense multiple access with collision detection (CSMA/CD)
If no one is transmitting, workstation can transmit
If someone else is transmitting, workstation “backs off” and waits
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7. Contention-Based Protocols (continued)
If two workstations transmit at same time, collision occurs
When two workstations hear collision, they stop transmitting immediately
Each workstation backs off a random amount of time and tries again
Hopefully, both workstations do not try again at exact same time
CSMA/CD is an example of a non-deterministic protocol
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8. CSMA/CD flow chart
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9. Round Robin based protocol
Bagaimana cara kerjanya?
Bandingkan mana yang lebih baik:
Dari sisi masa tunggu setiap workstation
Dari kapasitas maksimum
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10. LAN TOPOLOGY

11. The Bus/Tree The original topology
Workstation has a network interface card (NIC) that attaches to the bus (a coaxial cable) via a tap
Data can be transferred using either baseband digital signals or broadband analog signals
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12. Bus/Tree (continued)
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13. The Star-Wired Bus
Logically operates as a bus, but physically looks like a star
Star design is based on hub
All workstations attach to hub
Unshielded twisted pair usually used to connect workstation to hub
Originally, hub takes incoming signal and immediately broadcasts it out all connected links
Hubs can be interconnected to extend size of network
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14. Star-Wired Bus (continued)
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15. Star-Wired Bus (continued)
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16. Star-Wired Bus (continued)
Modular connectors and twisted pair make installation and maintenance of star-wired bus better than standard bus
Hubs can be interconnected with twisted pair, coaxial cable, or fiber-optic cable
Biggest disadvantage = when one station talks, everyone hears it
This is called a shared network
All devices are sharing the network medium
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17. Switch
Switches provide a unique network segment on each port, thereby separating collision domains.
Today, network designers are replacing hubs in their wiring closets with switches to increase their network performance and bandwidth while protecting their existing wiring investments.
Like bridges, switches learn certain information about the data packets that are received from various computers on the network.
Switches use this information to build forwarding tables to determine the destination of data being sent by one computer to another computer on the network.
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18. Switches: Dedicated Access
Hosts have direct connection to switch
Switching: A-to-A’ and B-to-B’ simultaneously, no collisions
Switches can be cascaded to expand the network A C’ B
switch B’ A’
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19. Switches
The hub is a simple device that transmits an incoming frame out all the other ports on the hub
The switch has intelligence and can filter out and forward frames based on their NIC address
A switch maintains internal port table(s) that keep track of which frames arrived on which ports
Switches have eliminated many hubs
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20. SWITCH vs HUB SWITCH HUB
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21. Switches (continued)
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22. Switches (continued)
A switch observes each frame that arrives at a port, extracts the source address from the frame, and places that address in the port’s routing table
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23. Switches (continued)
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24. Switches (continued)
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25. Switches (continued)
Workstations that connect to a hub are on a shared segment
Workstations that connect to a switch are on a switched segment
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26. Switches (continued)
The backplane of a switch is fast enough to support multiple data transfers at one time
A switch that employs cut-through architecture is passing on frame before entire frame has arrived at switch
Multiple workstations connected to a switch use dedicated segments
This is a very efficient way to isolate heavy users from the network
Can allow simultaneous access to multiple servers, or multiple simultaneous connections to a single server
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27. Switches (continued)
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28. Switches (continued)
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29. Providing Multiple Access
Whether shared or dedicated segments are involved, the primary goal of a switch is to isolate a particular pattern of traffic from other patterns of traffic or from the remainder of the network
Switches, because of their backplane, can also allow multiple paths of communications to simultaneously occur
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30. Providing Multiple Access (continued)
Using a pair of routers, it is possible to interconnect two switched segments, essentially creating one large local area network
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31. Providing Multiple Access (continued)
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32. Full-Duplex Switches
Allow for simultaneous transmission and reception of data to and from a workstation
This full-duplex connection helps to eliminate collisions
To support a full-duplex connection to a switch, at least two pairs of wires are necessary
One for the receive operation
One for the transmit operation
Most people install four pairs today, so wiring is not the problem
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33. Full Duplex Switches (continued)
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34. Virtual LANs
Virtual LAN (VLAN) – logical subgroup within a LAN that is created via switches and software rather than by manually moving wiring from one network device to another
Even though employees and their actual computer workstations may be scattered throughout the building, LAN switches and VLAN software can be used to create a “network within a network”
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35. Virtual LANs (continued)
A relatively new standard, IEEE 802.1Q, was designed to allow multiple devices to intercommunicate and work together to create a virtual LAN
Instead of sending technician to a wiring closet to move a workstation cable from one switch to another, an 802.1Q-compliant switch can be remotely configured by a network administrator
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36. Wired and wireless

37. Wired Ethernet Most common form of LAN today
Star-wired bus is most common topology but bus topology still not totally dead yet
Comes in many forms depending upon medium used and transmission speed and technology
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38. Wired Ethernet (continued)
Originally, CSMA/CD was 10 Mbps
Then 100 Mbps was introduced
Most NICs sold today are 10/100 Mbps
Then 1000 Mbps (1 Gbps) was introduced
10 Gbps is now being installed in high-end applications
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39. Wired Ethernet (continued)
1000 Mbps introduces a few interesting wrinkles:
Transmission is full-duplex (separate transmit and receive), thus no collisions
Prioritization is possible using 802.1p protocol
Topology can be star or mesh (for trunks)
Used to separate Delay sensitive traffic from loss sensitive traffic
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40. Wired Ethernet (continued)
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41. Wired Ethernet (continued)
One of the latest features is power over Ethernet (PoE)
What if you have a remote device that has an Ethernet connection?
It will require a power connection
What if you don’t have an electrical outlet nearby?
Use PoE
Power to drive Ethernet NIC is sent over wiring along with usual Ethernet signals
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42. Wireless Ethernet Not really a specific topology
Workstation in a wireless LAN can be anywhere as long as it is within transmitting distance to an access point
Several versions of IEEE standard define various forms of wireless LAN connections
Workstations reside within Basic Service Set, while multiple basic service sets create an Extended Service Set
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43. Wireless Ethernet (continued)
Two basic components necessary:
Client radio
Usually a PC card with an integrated antenna installed in a laptop or workstation
Access point (AP)
An Ethernet port plus a transceiver
AP acts as a bridge between the wired and wireless networks and can perform basic routing functions
Workstations with client radio cards reside within Basic Service Set, while multiple basic service sets create an Extended Service Set
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44. Wireless Ethernet (continued)
IEEE
June 1997
Original wireless standard, capable of transmitting data at 2 Mbps
IEEE b (Wireless Fidelity or WiFi)
Sep 1999
Second wireless standard, capable of transmitting data at 11 Mbps
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45. Wireless Ethernet (continued)
With directional antennae designed for point-to-point transmission (rare), b can transmit for more than 10 miles (16 km)
With an omni-directional antenna on typical AP, range may drop to as little as 100 feet (30 m)
Max transmission distance of b: up to 300 feet (90m) with 2.4 GHz frequency
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46. Wireless Ethernet (continued)
IEEE a, introduced in 2002
One of the faster standards
Capable of transmitting data at 54 Mbps (theoretical) using the 5-GHz frequency range
Max transmission distance of a: up to 90 feet (27m)
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47. Wireless Ethernet (continued)
IEEE g
Another fast standard, introduced in 2002
Also capable of transmitting data at 54 Mbps (theoretical) but using the same frequencies as b (2.4-GHz)
Is backwards compatible with b
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48. Wireless Ethernet (continued)
IEEE n is the latest standard to be approved:
Theoretical max data rate: 600Mbps
Actual data rate: 100 to 145 Mbps
802.11n uses MIMO technology (multiple input multiple output)
Sender and receiver have multiple antennas for optimum reception
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49. Wireless CSMA/CA CA (Collision avoidance) How does CSMA/CA do this?
Protocol does not listen and detect collisions
Instead, tries to avoid collisions before they happen
How does CSMA/CA do this?
All devices, before they transmit, must wait an amount of time called an inter frame space (IFS)
Some applications have a short IFS, while others have a long IFS
If two applications want to transmit at same time, the application with shorter IFS will go first
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50. CSMA/CA algorithm SIFS: Short IFS PIFS: Point coordinated IFS
DIFS: Distributed IFS
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51. Wireless LAN problem: Hidden Terminal
STAC
STAB
STAA
A and C are hidden
from each other. Both might try to send to B
And collide.
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53. Solution (partial) : RTS/CTS
CTS: Clear To Send
RTS
CTS C B A
CTS
STEPS
A sends RTS to B
B replies with CTS
A can send data
should refrain for some time
CTS
Exposed: RTS, no CTS D
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54. RTS CTS Frame Sequence Station AP RTS CTS Data ACK
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55. 2.4GHz band channels
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56. Frequency Planning
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57. Wireless Standard
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58. a, b and g
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59. Ip address and subnetting

60. IP Addresses and subnetting
All devices connected to Internet have either a 32-bit IPv4 address or a 128-bit IPv6 address
Think of the IP address as a logical address (possibly temporary), while the 48-bit address on every NIC is the physical, or permanent address
Computers, networks and routers use the 32-bit (or 128-bit) binary address, but a more readable form is the dotted decimal notation
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61. IP Addresses (continued)
For example, the 32-bit binary address
translates to
in dotted decimal notation
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62. IP Addresses (continued)
When IP addresses were originally created, they were called classfull addresses
That is, each IP address fell into particular class
A particular class address has a unique network address size and a unique host address size
There are basically five types of IP addresses: Classes A, B, C, D and E
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63. IP Addresses (continued)
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64. IP Addresses (continued)
When you examine the first decimal value in the dotted decimal notation:
All Class A addresses are in the range
All Class B addresses are in the range
All Class C addresses are in the range 192 – 223
All Class D addresses are in the range 224 – 239
All Class E addresses are in the range
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65. IP Addresses (continued)
IP subnet masking
Sometimes you have a large number of IP addresses to manage
By using subnet masking, you can break the host ID portion of the address into a subnet ID and host ID
Example – subnet mask applied to a class B address will break the host ID (normally 16 bits) into an 8-bit subnet ID and an 8-bit host ID
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66. IP Addresses (continued)
Today, IP addresses are considered classless addresses
With classless addressing, companies (users) do not apply for particular class of addresses
Instead, company will get its IP addresses from an Internet service provider (ISP)
Most ISPs have already applied for a large number of IP addresses and are willing to lease those addresses to companies
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67. IP Addresses (continued)
Example – instead of applying for two Class C addresses, a company could contact an ISP, which would lease 500 IP addresses to the company
The addresses are not identified by any class – they are simply a contiguous block of IP addresses
Classless addressing has led to a much more efficient allocation of the IP address space
A company can lease only as many addresses as it needs
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68. Subnetting Division of a network into subnets
For example, division of a Class B address into several Class C addresses
Some of the host IDs are used for creating subnet IDs
© N. Ganesan, All rights reserved. 68

69. Need for Subnetting
Classes A and B have a large number of hosts corresponding to each network ID
It may be desirable to subdivide the hosts in Class C subnets
Often, there is a limitation on the number of hosts that could be hosted on a single network segment
The limitation may be imposed by concerns related to the management of hardware
Smaller broadcast domains are more efficient and easy to manage
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70. Subnetting Principle Use parts of the host IDs for subnetting purpose
A subnet mask is used to facilitate the flow of traffic between the different subnets and the outside network (hops)
A hop is the distance a data packet travels form one node to the other
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71. Using Host IDs to Subnet
Subnetted Class B Network
140 15 1
Subnet 1
Full Class B Network
140 15 2
140 15
Subnet 2
140 15 3
Subnet 3
Third octet is borrowed to be used for subnet IDs 71

72. Subnet Configuration ….. Subnet ID (Network Address) 140 15 1 140 15 1
…..
140 15 1 1
140 15 1
254
First Host ID
Last Host ID 72

73. Slash notation
An IP address in slash notation has all the info we need about the block of addresses assigned to a user/company
For example, one address in a block of addresses is /27
27 bits belong to the network ID, and 5 bits belong to the host ID (IPv4 addresses have 32 bits)
The network mask has 27 1s followed by 5 0s. In dotted decimal notation that is
The number of addresses in the block is 25 = 32
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74. First and last address
To find the first address (network address), AND the address ( ) with the network mask ( )
Address:
Mask:
Result:
Which in decimal is /27
The last address (broadcast) is 31 addresses past the first, or /27
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75. Examples(1)
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76. Examples(2)
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77. IPv6 The next version of the Internet Protocol Main features include:
Simpler header
128-bit IP addresses
Priority levels and quality of service parameters
No fragmentation
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78. IPv6 (continued)
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79. Ipv6 Address 79 79

80. IPv6 Address Types 80 80 80 80

81. Thank you