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Comparing modem and other technologies

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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

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Communications Processors

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Telecommunications Processors

MultiplexerAllows a single communications channel to carry

simultaneous data transmissions from many terminals

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Telecommunications Software

Used by servers and other computers to manage network performance

Network Operating SystemsMiddleware

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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

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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

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Network Topologies

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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

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OSI & TCP/IP Models

Open Systems Interconnection (OSI) ModelA seven-layer model that serves as a standard

model for network architecturesModel for how messages should be transmitted

between two points in a networkEach layer adds functions

Transmission Control Protocol / Internet Protocol (TCP/IP)A five layer telecommunications protocol used

by the Internet

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OSI & TCP/IP Models

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Internet Telephony

Using an Internet connection to pass voice data using IP

Voice over IP (VoIP)Skips standard long-distance phone charges

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Bandwidth

BandwidthFrequency range of a telecommunications

channelDetermines transmission rateClassified in bits per second (bps)

Transmission Rates:Narrow-band – low-speedBroadband – high-speed

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Transmission Speeds

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Switching Alternatives

Circuit Switching Switch opens a circuit to establish a link

between a sender and receiverit remains open until the communication session

is completedPacket Switching

Break messages into groups called packetsTransmit packets separately

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Network Interoperability

Ensure that anyone anywhere on one networkCan communicateWith anyone anywhere on another network

Telecommunications as discussed in this chapter wouldn’t be possible without interoperability

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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

InternetPackets are reassembled at the destination

Minnesota Department of Labor has cut its monthly phone bill in half

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Case Study Questions

1. What are the main benefits that can be gained by companies that switch to VoIP systems?

2. What are some of the major cost factors that may limit a positive rate of return from investments in VoIP projects?

3. 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.

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Real World Internet Activity

1. 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?

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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?