1. Networking Fundamentals
CMPSC 255
Fall 2004

2. Aims By the end of this Module you should be able to:
Briefly outline the history of networking.
Identify devices used in networking.
Understand the role of protocols in networking.
Define LAN, WAN, MAN, and SAN.
Explain VPNs and their advantages.
Describe the differences between intranets and extranets.
Explain bandwidth in networking as units of measurement.
Explain the difference between bandwidth and throughput.
Calculate data transfer rates.
Describe the OSI Model in relation to Layers, Functions, Protocols and Devices
Identify the four layers of the TCP/IP model and describe the similarities and differences between the two models.

3. Network Evolution Sneakernet Used when few computers were available
Stand alone computers
Files transferred by copying to disk and physically delivering it to destination
Makes it difficult to track current file version
Wastes time

4. Network Evolution Local Area Networks
Connected computers on a shared medium
Enabled users to share files electronically
More efficient
Standards developed to allow equipment from different vendors to interoperate

5. Network Evolution Wide Area Networks
As corporations grew wider communication was needed
Each branch of a corporation became isolated
Files sent by post or courier
Solution
WAN standards developed
Companies were able to communicate with other networks globally

6. Network Terminology
Network Devices

7. Topologies Network Topologies Describe Structure of the network
Physical Layout of Cabling (Physical Topology)
How the media is accessed by communicating hosts (Logical Topology)
Common Physical Topologies

8. Bus Topology
Uses a single backbone cable that is terminated at both ends.
All the hosts connect directly to this backbone
Bandwidth is shared between the number of hosts on Network
Can be Logical or Physical

9. Star Topology
A star topology connects all cables to a central point of concentration
Can be a Logical Bus or Ring
Concentrator can be a
Hub
Switch
MSAU

10. Ring Topology
Connects one host to the next and the last host to the first
This creates a physical ring of cable
Can be Logical or Physical

11. Extended Star Topology
Links individual star wired network segments together
Uses hubs and/or switches
This topology can extend the scope and coverage of the network

12. Hierarchical Topology
Similar to an extended star
Instead of linking the hubs and/or switches together, the system is linked to a computer that controls the traffic on the topology

13. Mesh Topology
Implemented to provide as much protection as possible from interruption of service
The use of a mesh topology in the networked control systems of a nuclear power plant would be an excellent example
Each host has its own connections to all other hosts.
Internet has multiple paths to any one location but it does not adopt the full mesh topology.

14. Logical Topologies Defines how the hosts communicate across the medium
The two most common types of logical topologies are:
Broadcast topology
means that each host sends its data to all other hosts on the network medium. There is no order that the stations must follow to use the network.
It is first come, first serve. Ethernet works this way as will be explained later in the course.
Token passing
controls network access by passing an electronic token sequentially to each host.
When a host receives the token, that host can send data on the network. If the host has no data to send, it passes the token to the next host and the process repeats itself.
Two examples of networks that use token passing are Token Ring and Fiber Distributed Data Interface (FDDI).
A variation of Token Ring and FDDI is Arcnet. Arcnet is token passing on a bus topology.

15. Network Protocols
Protocol suites are collections of protocols that enable network communication from one host through the network to another host.
A protocol is a formal description of a set of rules and conventions that govern a particular aspect of how devices on a network communicate.
Protocols determine the format, timing, sequencing, and error control in data communication.
Protocols control data communication, which include the following:
How the physical network is built
How computers connect to the network
How the data is formatted for transmission
How that data is sent
How to deal with errors

16. Network Protocols
Protocols are created and maintained by organizations and committees such as:
Institute of Electrical and Electronic Engineers (IEEE)
American National Standards Institute (ANSI)
Telecommunications Industry Association (TIA)
Electronic Industries Alliance (EIA)
International Telecommunications Union (ITU)

17. Local Area Networks (LANs)
LANs consist of the following components:
Computers
Network interface cards
Peripheral devices
Networking media
Network devices

18. LAN Components LANs are designed to:
Operate in a limited geographical area
Allow multiple access to high-bandwidth media
Control the network privately under local administrative control
Provide full time connectivity to local services
Connect physically adjacent devices

19. WAN Components WANs are designed to:
Operate over a large geographical area
Allow access over serial interfaces at lower speeds
Provide full and part time connectivity
Connect devices separated over wide, even global areas

20. LAN and WAN Technologies
Common LAN technologies are:
Ethernet
Token Ring
FDDI
Common WAN technologies are:
Modems
Integrated Services Digital Network (ISDN)
Digital Subscriber Line (DSL)
Frame Relay
US (T) and Europe (E) Carrier Series – T1, E1, T3, E3
Synchronous Optical Network (SONET)

21. Metropolitan Area Network
A network that spans a metropolitan area such as a city or suburban area.
Usually consists of two or more LANs in a common geographic area.
A service provider is used to connect two or more LAN sites
Can also be created using wireless technology

22. Storage Area Network
A dedicated, high-performance network used to move data between servers and storage resources.
SAN technology allows high-speed server-to-storage,
Offers the following features:
Availability
Scalability

23. Virtual Private Networks
A private network that is constructed within a public network infrastructure such as the Internet
Uses a secure tunnel through the Internet between the telecommuter’s PC and a VPN router in the headquarters

24. Intranet and Extranet VPNs

25. Bandwidth Why Bandwidth is important
Bandwidth is limited by Physics and Technology
Regardless of the media used to build the network there are limits on the capacity of that network to carry information.
Bandwidth is limited by the laws of physics and by the technologies used to place information on the media.
Bandwidth is not free
WAN connectivity must be purchased from a service provider
Bandwidth requirements are growing at a rapid rate
More and more companies are using WAN services which require more and more bandwidth
Bandwidth is critical to network performance
The higher the bandwidth the more information can be transferred in a shorter time

26. Bandwidth
Bandwidth Analogy 1

27. Bandwidth
Bandwidth Analogy 2

28. Bandwidth Units of Bandwidth
Bandwidth is the measure of how much information, or bits, can flow from one place to another in a given amount of time
Although bandwidth can be described in bits per second, usually some multiple of bits per second is used.

29. Limitations Bandwidth is limited by a number of factors Media
Network devices
Physics
Each have their own limiting factors
Actual bandwidth of a network is determined by a combination of the physical media and the technologies chosen for signaling and detecting network signals

30. Media bandwidth and limitations
Max Length
Max Bandwidth
50 Ohm Coaxial Cable
(10Base2) Thin Ethernet
185m
10Mbps
(10Base5) Thick Ethernet
500m
Category 5 Unshielded Twisted Pair (UTP)
(10BaseT) Ethernet
100m
(100BaseTX) Ethernet
100Mbps
(1000BaseTX) Ethernet
1000Mbps
Multimode Optical Fibre
62.5/125mm 100BaseFX Ethernet
2000m
62.5/125mm 1000BaseSX Ethernet
220m
50/125mm 1000BaseSX Ethernet
550m
Single mode Optical Fibre
9/125mm 1000BaseLX Ethernet
5000m

31. Throughput Throughput refers to actual measured bandwidth at:
a specific time of day
using specific Internet routes
and while a specific set of data is transmitted on the network.
Is determines by the following factors
Internetworking devices
Type of data being transferred
Network topology
Number of users on the network
User computer
Server computer
Power conditions

32. Transfer Time Calculation
Data Transfer Calculation
Best Download: T=S/BW
Typical Bandwidth: T=S/P
Where
T = Transfer time in seconds
S = Size of file in Bits
BW = Maximum theoretical bandwidth (slowest link between source and destination devices
P = Actual throughput at moment of transfer in Bps

33. Layered models Using a layered model
Breaks network communication into smaller, more manageable parts.
Standardizes network components to allow multiple vendor development and support.
Allows different types of network hardware and software to communicate with each other.
Prevents changes in one layer from affecting other layers.
Divides network communication into smaller parts to make learning it easier to understand.

34. OSI Model Open Standards Interconnection Model (OSI Model)
Released by International Standards Organisation (ISO) in 1984
Standardised communications between different vendor hardware and software
Consists of 7 Layers
Each layer described a specific aspect of network communication

35. Layer 1
The physical layer is concerned with transmitting raw bits over a medium
Wires
Connectors
Voltages
Data rates

36. Layer 2 Controls the direct link to the media How media is accessed
Physical addressing
Network topology
Flow control
Error Notification

37. Layer 3 Logical Addressing Best Path Determination
“Best Effort” delivery of data between networks

38. Layer 4 End-to-end Connections
Concerned with transportation issues between hosts
Reliable delivery of data
Establishes, maintains and terminates virtual circuits
Error recovery and data flow

39. Layer 5 Host to host communication
Establishes, manages and terminates sessions between applications

40. Layer 6 Data representation
Ensure data is readable with receiving system
Data format
Data Structure
Negotiates data transfer syntax for application layer

41. Layer 7 Provides network services for applications
, file transfer, terminal emulation

42. Peer to Peer Communication
Host 1
Host 2

43. TCP/IP Model Developed by the US DoD Designed as an open standard
Is robust enough to survive any conditions (even nuclear war)
Is the standard used for communication on the Internet

44. TCP/IP Vs OSI
TCT/IP
OSI

45. Labs Lab 2.3.6 OSI Model and TCP/IP Model Lab 2.3.7
OSI Model Characteristics and Devices

46. TCP/IP Protocols

47. Protocols and TCP/IP

48. Data Encapsulation

49. Analog Vs Digital
Is measured by how much of the electromagnetic spectrum is occupied by each signal
The basic unit of analog bandwidth is hertz (Hz)
Units of measurement that are commonly seen are
kilohertz (KHz)
megahertz (MHz)
gigahertz (GHz).
These are the units used to describe the bandwidths of cordless telephones
Operate at either 900 MHz or 2.4 GHz.
These are also the units used to describe the bandwidths of IEEE a and b wireless networks
operate at 5 GHz and 2.4 GHz.