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6-2
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
6-4
Telecommunications Processors
MultiplexerAllows a single communications channel to carry
simultaneous data transmissions from many terminals
6-5
Telecommunications Software
Used by servers and other computers to manage network performance
Network Operating SystemsMiddleware
6-6
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
6-7
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
6-9
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
6-10
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
6-12
Internet Telephony
Using an Internet connection to pass voice data using IP
Voice over IP (VoIP)Skips standard long-distance phone charges
6-13
Bandwidth
BandwidthFrequency range of a telecommunications
channelDetermines transmission rateClassified in bits per second (bps)
Transmission Rates:Narrow-band – low-speedBroadband – high-speed
6-15
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
6-16
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
6-17
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
InternetPackets are reassembled at the destination
Minnesota Department of Labor has cut its monthly phone bill in half
6-18
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.
6-19
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?
6-20
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?