1. Comparing modem and other technologies

2. Internetwork Processors
Switch – makes connections between telecommunications circuits in a network
Router – intelligent communications processor that interconnects networks based on different protocols
Hub – a port switching communications processor
Gateway – connects networks using different communications architectures

3. Communications Processors
Corporate LAN in upper left hand corner uses a hub to connect its multiple workstations to the network switch. The switch sends the signals to a series of switches and routers to get the data to its destination.

4. Telecommunications Processors
Multiplexer
Allows a single communications channel to carry simultaneous data transmissions from many terminals

5. Telecommunications Software
Used by servers and other computers to manage network performance
Network Operating Systems
Middleware

6. Network management functions
Traffic Management – manage network resources and traffic to avoid congestion and optimize service levels to users
Security – provide authentication, encryption, firewall, auditing and enforcement
Network Monitoring – troubleshoot and watch over the network, informing network administrators of potential problems before they occur
Capacity Planning – survey network resources and traffic patterns and users’ needs to determine how best to accommodate the needs of the network as it grows and changes

7. Network Topologies Topology: structure of a network
Star: ties end user computers to a central computer
Ring: ties local computer processors together in a ring on a relatively equal basis
Bus: local processors share the same communications channel

8. Network Topologies

9. Network Architectures & Protocols
Protocol: standard set of rules and procedures for the control of communications in a network
Network Architecture:
Master plan of standard protocols, hardware, software and interfaces between end users and computer systems
Goal of promoting an open, simple, flexible, and efficient telecommunications environment

10. OSI & TCP/IP Models Open Systems Interconnection (OSI) Model
A seven-layer model that serves as a standard model for network architectures
Model for how messages should be transmitted between two points in a network
Each layer adds functions
Transmission Control Protocol / Internet Protocol (TCP/IP)
A five layer telecommunications protocol used by the Internet

11. OSI & TCP/IP Models Two groups of layers.
Upper four layers are used whenever a message passes from or to a user.
Lower three layers are used when message passes through the host computer. If message is being sent to another host, it skips these layers.
TCP/IP analogous to postal system.
TCP: analogous to postal system and processes and protocols to use the mail.
IP: analogous to zip code and address.

12. Internet Telephony
Using an Internet connection to pass voice data using IP
Voice over IP (VoIP)
Skips standard long-distance phone charges

13. Bandwidth Bandwidth Transmission Rates:
Frequency range of a telecommunications channel
Determines transmission rate
Classified in bits per second (bps)
Transmission Rates:
Narrow-band – low-speed
Broadband – high-speed
Bandwidth is sometimes called baud rate.
Think of channel as a pipe with water in it. The wider the pipe, the more water that can flow through it.
Narrow-band – unshielded twisted-pair
Broadband – microwave, fiber optic or satellite

14. Transmission Speeds

15. Switching Alternatives
Circuit Switching
Switch opens a circuit to establish a link between a sender and receiver
it remains open until the communication session is completed
Packet Switching
Break messages into groups called packets
Transmit packets separately
Circuit switching: telephone service
Packet switching: Internet, x.25 protocols, ATM

16. Network Interoperability
Ensure that anyone anywhere on one network
Can communicate
With anyone anywhere on another network
Telecommunications as discussed in this chapter wouldn’t be possible without interoperability

17. Case 3: Voice Over IP is the Real Thing
VoIP works by
Digitizing a voice signal,
Chopping it into packets, and
Sending them over a company’s network or the Internet
Packets are reassembled at the destination
Minnesota Department of Labor has cut its monthly phone bill in half

18. Case Study Questions
What are the main benefits that can be gained by companies that switch to VoIP systems?
What are some of the major cost factors that may limit a positive rate of return from investments in VoIP projects?
Should more companies switch to VoIP systems? Visit the websites of Avaya and Cisco Systems to view their VoIP news, products, and services to help you answer.

19. Real World Internet Activity
VoIP is becoming a highly competitive marketplace for the delivery of services and the development of software to support the process. Using the Internet,
See if you can identify who the major players are in this market.
Where do you see the next significant development for VoIP?
Do you think the concept will eventually replace conventional telephone technologies? Why or why not?

20. Real World Group Activity
The original concept for the Internet never included many of the uses we have found for it and consider commonplace today. While Internet2 is on the horizon, we need to think about what uses we may want from the Internet in the future. In small groups,
Brainstorm how we might use the Internet in the future.
Do we run the risk of overloading the Internet or relying on it too much?