Analysis: Guide To Networks

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Network+ Guide to Networks
6th Edition

Voice and Video Over IP

• Use terminology specific to converged networks
• Explain VoIP (Voice over IP) services, PBXs, and their user interfaces
• Explain video-over-IP services and their user interfaces Network+ Guide to Networks, 6th Edition


• IP telephony (VoIP)
– Any network carrying voice signals using TCP/IP
• Public or private

– Runs over any packet-switched network

• Data connection types carrying VoIP signals
– T-carriers, ISDN, DSL, broadband cable, satellite connections, WiFi, WiMAX, HSPA+, LTE, cellular telephone networks

Network+ Guide to Networks, 6th Edition


Terminology (cont’d.)
• Internet telephony
– VoIP calls carried over Internet
– Advantages: breadth, low cost

• Private lines

Carry VoIP calls
Effective and economical
Network congestion control capabilities
Better sound quality

Network+ Guide to Networks, 6th Edition


Terminology (cont’d.)
• Nondata applications on converged networks
– IPTV (IP television)
– Videoconferencing
• Multiple participants communicate and collaborate via audiovisual means

– Streaming video
• Compressed video delivered in continuous stream

– Webcasts
• Streaming videos supplied via the Web

Network+ Guide to Networks, 6th Edition


Terminology (cont’d.)
• Multicasting
– One node transmits same content to every client in group • Video over IP
– IPTV, videoconferencing, streaming video, IP multicasting • Unified communications (unified messaging) service
– Several communication forms available from single user interface

Network+ Guide to Networks, 6th Edition


VoIP Applications and Interfaces
• Reasons for implementing VoIP
– Lower voice call cost
– New, enhanced features and applications
– Centralize voice and data network management

• Voice and data configurations
– Traditional telephone (sends, receives analog signals)
– Telephone specially designed for TCP/IP transmission
– Computer with microphone, speaker, VoIP client software – Mixture of these types
Network+ Guide to Networks, 6th Edition


Analog Telephones
• Traditional telephone used for VoIP
– Signals converted to digital form

• Codec
– Method of compressing, encoding, analog signals

• ATA (analog telephone adapter)

Card within computer workstation
Externally attached device
Telephone line connects to RJ-11 adapter port
Converts analog voice signals to IP packets

Network+ Guide to Networks, 6th Edition


Figure 12-1 ATA (analog telephone adapter)
Courtesy of Grandstream Networks, Inc.

Network+ Guide to Networks, 6th Edition


Analog Telephones (cont’d.)
• Alternate analog-to-digital conversion method
– Connect analog telephone line to switch, router, or gateway – Convert analog voice signals into packet
– Issue packet to data network
– Vice versa

Network+ Guide to Networks, 6th Edition


Figure 12-2 VoIP router
Photo of SmartNode™4520 Analog VoIP router from Patton Electronics , Co.

Network+ Guide to Networks, 6th Edition


Analog Telephones (cont’d.)
• Digital PBX (private branch exchange)
– More commonly called IP-PBX
– Telephone switch connecting and managing calls within private organization
– Accepts, interprets analog and digital voice signals
– Connects with traditional PSTN lines, data networks
– Transmits, receives IP-based voice signals to and from other network connectivity devices
– Packaged with sophisticated software

Network+ Guide to Networks, 6th Edition


Figure 12-3 IP-PBX
Courtesy of Epygi Technologies, Ltd.

Network+ Guide to Networks, 6th Edition


Analog Telephones (cont’d.)
• Traditional telephone connects to analog PBX
– Then connects to voice-data gateway

• Gateway connects traditional telephone circuits with
TCP/IP network
– Internet or private WAN

• Gateway actions

Digitizes incoming analog voice signal
Compresses data
Assembles data into packets
Issues packets to packet-switched network

Network+ Guide to Networks, 6th Edition