This was the overview for the basics of the OSI model and the concepts around networking for an NIU course I taught on networking. Another instructor also named Steve taught the course previously, and much of the presentation was based on his work but I can't remember what was modified. It was meant for educators without a deep technical background. .

1. LAN FundamentalsLAN Fundamentals
ETT 592
LAN Administration

2. Network ModelsNetwork Models
• Shared Processing
• Distributed Processing
– Peer to Peer
– Client Server

3. Shared ProcessingShared Processing
• Mainframe/Unix/Windows Terminal
Server environment
• All users share the same processor
• Users connect via “terminal emulation”

4. Peer to PeerPeer to Peer
• EASY!!!!
• CHEAP!!!!!
• Allows File and
Peripheral Sharing
• No centralized
control
• Generally insecure
• Unreliable

5. Client ServerClient Server
• Centralized
Management
• High Security
• Reduced client
management
• Easy backup
• Scalability
• Higher hardware
cost (dedicated
server)
• Server is failure
point
• More difficult to
manage

6. LAN ComponentsLAN Components
• File Server
• Application Software
• Workstations / Client OS
• NICs
• Shared Peripherals
• Data Files
• NOS

7. File ServerFile Server
• Central system
• Controls authentication
• Provides management of resources and
peripherals
• Often multi-processor
• Significant HD capacity
• BIG Box
• Becomes the weakest link

8. Application SoftwareApplication Software
• Programs that perform tasks
– Office Suites
– Database applications

9. WorkstationWorkstation
• Provide connection to network
• May or may not have HD
• May or may not be “dumb terminals”
• Can be running a variety of OS’s
depending on network capabilities

10. Workstation OSWorkstation OS
• Singletasking vs. Multitasking
– Cooperative (like kids sharing)
– Preemptive (like kids sharing with
supervision)
• Single User vs. Multi User
• Network protocol support

11. NICsNICs
• Network Interface Cards
• Allow physical connection between
network and the computer
• Manufactured by MANY companies.
– Buy from a major vendor
– Try to standardize

12. Data FilesData Files
• The most significant reason we network
today
• Provides shared, controlled access to
resources
• Provides centralized backup of
resources

13. Server StorageServer Storage
• HD capacity
• MTBF
• RAID 0, 1, 5

14. So What is RAID ???So What is RAID ???
• Redundant Array of Inexpensive Disks
• Can be done through OS or using
special SCSI controller cards

15. RAID 0RAID 0
• Disk Striping w/o parity
• Data written to multiple disks
• No increase in security
• Great Increase in I/O

16. RAID 1RAID 1
• Disk Mirroring / Duplexing
• Mirroring
– Two drives, single controller
– Redundancy, no I/O benefit
• Duplexing
– Two drives, two controllers
– Redundancy, I/O read benefit
• Storage capacity ½ of drive space

17. RAID 5RAID 5
• Disk Striping with Parity
• Data and parity blocks spread across all
drives
• Writes may be a bit slower
• Reads are faster
• Get redundancy
• Storage capacity is #drives-1

18. Shared PeripheralsShared Peripherals
• Printers
• Fax Servers

19. NOSNOS
• Network Operating Systems
• Windows NT
• Windows 2000
• Windows XP
• Unix / Linux
• Mac OS X

20. Hot SwapHot Swap
• Ability to replace parts while system is
running
– Power supplies
– HD

21. The weakest linkThe weakest link
• Server failure or downtime leads to
productivity loss
– Clustering prevents this
• Server failure leads to inability to authenticate
– PDC and BDC
• File retrieval is often slower
– Data files compared to application software
• Security Problems

22. The weakest link (cont)The weakest link (cont)
• Power Problems
– Redundant power supplies
– UPS
– Generators

23. How are networks builtHow are networks built
• Several components that must first be
considered.

24. Network TopologiesNetwork Topologies
• Bus
• Star
• Ring
• Mesh

25. Access TypesAccess Types
• Contention Based
– CSMA/CD
• Deterministic
– Token Passing

26. Cable TypesCable Types
• Coax
– RG58
• UTP
– CAT3
– CAT5
– CAT6e
• Fiber Optic

27. Network TypesNetwork Types
• Ethernet
– 10Base-2
– 10Base-T
– 100Base-T
• Token Ring
– Standard Token Ring
– FDDI

28. 10Base-210Base-2
• Bus Configuration
• RG58 wire with 50ohm terminator

29. 10Base-210Base-2
• Maximum Segment Distance 185m
(607 ft)
• Maximum network length 925m(3,035
ft)

30. 10Base-T/ 10Base-10010Base-T/ 10Base-100
• Ethernet / Star configuration
• Category 3 UTP=10mbs
• Category 5 UTP=100mbs

31. 10Base-T/ 10Base-10010Base-T/ 10Base-100
• Number of stations set by concentrator
• 1,024 stations per network
• 100 m to concentrator (328 ft)

32. Token RingToken Ring
• Token Passing Scheme
• Systems are connected to MAU
• Operate at 4 or 16mb
• Now use “Early Token Release”
• Tend to handle network load better

33. FDDI (Fiber DistributedFDDI (Fiber Distributed
Data Interface)Data Interface)
• Token passing scheme
• Dual counter rotating rings
• Fiber optic cable
• Class A connections are fault tolerant
• Class B connections are not fault
tolerant

34. How do the parts workHow do the parts work
togethertogether
• OSI Model is the theoretical basis
• No one adheres exactly to the model,
but everyone understands what it
means.

35. OSI ModelOSI Model
http://webopedia.internet.com/quick_ref/OSI_Layers.html

36. Physical LayerPhysical Layer
• Cabling, Topology
• Electrical Communications Stuff
• Cable and how it connects to the card

37. Data LinkData Link
• Organizes frames into structured data
packets
• 802.3 (CSMA/CD Ethernet)
• 802.5 (Token Ring)
• 802.11 (Wireless)

38. Network LayerNetwork Layer
• Responsible for routing data in
subnetted network
– If a transport protocol doesn’t support this
layer it is unroutable
• IP address converted to/from MAC
Address

39. Transport LayerTransport Layer
• Makes sure data gets from one point to
another
• Error Detection and recovery

40. Session LayerSession Layer
• Logical connection between network
devices

41. Presentation LayerPresentation Layer
• Translates data from application layer
to transmission format
• Encoding/Decoding
• ASCII, .DOC, .MPG, .JPG

42. Application LayerApplication Layer
• End User Software
• Email, File Transfer, Word,

43. How to rememberHow to remember
• Application
• Presentation
• Session
• Transport
• Network
• Data Link
• Physical
Please Do Not Throw Sausage Pizza Away

44. Network GearNetwork Gear
• Hubs ( a splitter )
– OSI layer 1 (Physical)
• Switches ( an intelligent splitter )
– OSI layer 2 (Data Link)
• MAUs ( a hub for a token ring network )
– OSI layer 1 (Physical)
• Routers (moves data between networks and
subnets )
– OSI layer 3 (Network)

45. IP AddressingIP Addressing
• Address Classifications
• Subnetting

46. IP Address ClassesIP Address Classes
Class Range # Networks Hosts/
Network
A 1-126 126 16,777,214
B 128-191.255 16,384 65,534
C 192.0.0-
225.255.255
2,097,152 254

47. So you want an addressSo you want an address
• Class A addresses are all gone
• Class B addresses are basically gone
• Class C addresses are available

48. Reserved AddressesReserved Addresses
• Class A 10.0.0.0-10.255.255.255
• Class B 172.16.0.0 – 172.31.255.255
• Class C 192.168.0.0 – 192.168.255.255
• Loop Back 127.0.0.1
• Reserved addresses are NEVER routed

49. What’s a subnet?What’s a subnet?
• Logical organization of computers
• A way to reduce network traffic
• A way to efficiently use assigned
addresses

50. Getting an IP addressGetting an IP address
• Hard Coding
– Manual Entry of
• DNS Servers (Domain Name Services)
• Gateways (Routers)
• IP Address
• DHCP
– Dynamic Host Control Protocol

51. IP ConfigurationIP Configuration
ExampleExample