1. ITEC350 Networks I Lecture 1
Hwajung Lee

2. References
Panko, “Business Data Networks and Telecommunications,” 4th Edition, Prentice Hall, 2003.
Tanenbaum, “Computer Networks,” 4th Edition, Prentice Hall PTR, 2003.
Wells, “Guide to Linux Networking and Securitity,” Course Technology, 2003.
Minasi, “Mastering Windows Server 2003,” SYBEX Inc., 2003.

3. What is Computer Networks?
A collection of autonomous computers interconnected by a single technology
Interconnected via:
Copper wire
Fiber optics
Microwaves
Infrared
Communication satellites, etc.

4. Why Computer Networks? Business Applications [Goal1] Resource Sharing
To connect isolated computer and information to be able to extract and correlate information about the entire company.
To make all programs, equipment (ex: printers, scanners, and CD burners), and especially data available to anyone on the network without regard to the physical location of the resource an the user.

5. [Goal 2] Communication Medium
Electronic mail ( )
Shared resources (ex: shared hard driver)
Videoconferencing, a shared virtual blackboard

6. [Goal 3] Electronic Commerce (e-commerce)
To do business electronically with other companies. (ex: order the parts of a product from a variety of suppliers)
To do business with consumers over the Internet.

7. Home Applications [Goal 1] Access to remote information
Newspapers, Digital library
[Goal 2] Person-to-person communication
, Instant messaging, Chat room, Worldwide newsgroups
Peer-to-peer communication (ex: Napster)
Internet phone, Internet video phone, Internet radio, Telelearning

8. Home Applications (cont.)
[Goal 3] Interactive entertainment
Video on demand, Interactive live television show, Multiperson real-time simulation games – possibly with worldwide shared virtual reality.
[Goal 4] Electronic commerce
Home shopping, Electric flea markets, On-line auctions

9. Mobile Network Users [Goal] To have a portable office
Cellular phone, PDA, Military use, Wireless sensor networks, Mobile-commerce, Wearable wireless computers
Combinations of wireless networks and mobile computing.

10. Network Types Based on Roles
Terminal Connection

11. Network Types Based on Roles
Client-server

12. Network Types Based on Roles
Peer-to-peer
Computers act as both client and server on the network
There is no reliance on a centralized server to provide access to data and other resources
Compared to a centralized client-server model, peer-to-peer is decentralized, meaning any host can communicate with any other host

13. Network Topologies
RING
STAR
MESH
HYBRIDS
OF THESE
BUS

14. Comparison of Basic Topologies
Topology
Bus
Star
Ring
Advantages
Physical Broadcast
Inherent Security, Limited Delay
Reliability, Limited Delay
Disadvantages
Poor
Security – All stations see the data at once
Inefficient – collisions when two or more stations send at once.
Poor Reliability (central controller is single point of failure)
Poor Security – All stations see the data as is travels around the ring

15. Classification of interconnected processors by scale.

16. Personal Area Network (PAN)
A person’s body or desk area

17. Local Area Networks (1) Local Area Network (LAN)
Limited geographical distance: home, office, building, campus, industrial part
Customer premises operation
User firm chooses technology
User firm needs to manage on ongoing basis
Low cost per bit transmitted
Companies can afford high speed
100 Mbps to the desktop is typical

18. Local Area Networks (2)
Two broadcast networks
(a) Bus (b) Ring

19. Architecture of the original Ethernet.
Local Area Networks (3)
Ethernet
Most popular LAN
Architecture of the original Ethernet.

20. Metropolitan Area Networks
Metropolitan Area Network (MAN)
Single urban area (city and its suburbs)
Faster than long-distance WANs
Still slower than LANs

21. Metropolitan Area Networks
A metropolitan area network based on cable TV.

22. Wide Area Network (WAN)
To link sites
Long distances
Requires the use of carriers to provide service
Limited and complex choices but carrier manages
High cost per bit transmitted
Companies cannot afford high speeds
Usually low speed (56 kbps to a few megabits per second)

23. Relation between hosts on LANs and the subnet.
Wide Area Networks (1)
Relation between hosts on LANs and the subnet.

24. A stream of packets from sender to receiver.
Wide Area Networks (2)
A stream of packets from sender to receiver.

25. Wireless Networks Categories of wireless networks:
System interconnection
Wireless LANs
Speed: Upto about 50Mbps
Distance: Tens of meters
Wireless WANs (ex: cellular system)
Speed: below 1Mbps
Distance: Kilometers

26. (a) Bluetooth configuration (b) Wireless LAN
Wireless Networks (2)
(a) Bluetooth configuration (b) Wireless LAN

27. Wireless LANs (a) Wireless networking with a base station.
(b) Ad hoc networking.

28. Standard for Wireless LANs
IEEE network.

29. Wireless WAN Networks
(a) Individual mobile computers
(b) A flying LAN

30. Network Software Protocol Hierarchies Design Issues for the Layers
Connection-Oriented and Connectionless Services
Service Primitives
The Relationship of Services to Protocols

31. Network Software Protocol Hierarchies
Layers, protocols, and interfaces.

32. The philosopher-translator-secretary architecture.
Protocol Hierarchies
The philosopher-translator-secretary architecture.

33. Protocol Hierarchies (3)
Example information flow supporting virtual communication in layer 5.

34. Design Issues for the Layers
Addressing
Error Control
Flow Control
Multiplexing
Routing

35. Connection-Oriented and Connectionless Services
The software used to maintain each protocol is often called a protocol stack
Transport layer protocols can be:
Connectionless, or stateless, which sends each packet without regard to whether any other packet was received by the destination computer (implementation: packet switching, UDP)
Connection oriented, or stateful, which maintains information about which packets have been correctly received by the destination computer (implm.:circuit-switching, TCP)

36. Connection-Oriented and Connectionless Services
Six different types of service.

37. Service Primitives
Five service primitives for implementing a simple connection-oriented service.

38. Service Primitives (2)
Packets sent in a simple client-server interaction on a connection-oriented network.

39. Services to Protocols Relationship
The relationship between a service and a protocol.

40. Why Standard or Reference Model?
Consumer
Easy to select a product which is compatible with other equipments.
Supplier
Minimize risk when it develops new technologies.

41. Reference Models The OSI Reference Model The TCP/IP Reference Model
ISO (International Organization for Standardization)
OSI (Open Systems Interconnection) Model
The TCP/IP Reference Model
TCP (Transmission Control Protocol)
IP (Internet Protocol)
A Critique of the OSI Model and Protocols
A Critique of the TCP/IP Reference Model

42. OSI Reference Model

43. OSI Reference Model

44. The TCP/IP reference model

45. Conceptual Models of Networking (1)

46. Acronyms POP (Post Office Protocol) FTP (File Transfer Protocol)
UDP (User Datagram Protocol)
TCP (Transmission Control Protocol)
SMTP (Simple Mail Transport Protocol)
HTTP (Hypertext Transport Protocol)
DNS (Domain Name Service)
ICMP (Internet Control Message Protocol)
PPP (Point-to-Point Protocol)
SATNET (Satellite Networks)
IRC (Internet Relay Chat)

47. A Critique of the OSI Model and Protocols
Why OSI did not take over the world
Bad timing
Bad implementations
Bad politics

48. Bad Timing
The apocalypse of the two elephants.

49. A Critique of the TCP/IP Reference Model
Problems:
Service, interface, and protocol not distinguished
Not a general model
Host-to-network “layer” not really a layer
No mention of physical and data link layers
Minor protocols deeply entrenched, hard to replace

50. Networking Technologies
Ethernet
Most widely used technology
Three variation of Ethernet based on transmission speed, or bandwidth
Token-ring
Uses a token to identify which computer on the network has the right to transmit data
Not as fast as Ethernet, and may be more expensive

51. Networking Technologies
Fiber Distributed Data Interface (FDDI)
Reliable, but slower and costlier than Ethernet
Arcnet
Reliable, but slower token-passing technology
Asynchronous Transfer Mode (ATM)
high-speed, very reliable and very expensive used for Internet backbones
Wireless LAN (WLAN)
No cables used to connect nodes to the network
Data is transmitted via radio signals of infrared

52. Networking Technologies

53. Network Standardization
Who’s Who in the Telecommunications World
Who’s Who in the International Standards World
Who’s Who in the Internet Standards World

54. ITU (International Telecommunication Union)
Main sectors
Radiocommunications
Telecommunications Standardization
Development
Classes of Members
National governments
Sector members
Associate members
Regulatory agencies

55. IEEE 802 Standards
The 802 working groups. The important ones are marked with *. The ones marked with  are hibernating. The one marked with † gave up.

56. The principal metric prefixes.
Metric Units
The principal metric prefixes.