WANs and Remote Connectivity Describe the wireless spectrum. Describe how interf
ID: 3675463 • Letter: W
Question
WANs and Remote Connectivity
Describe the wireless spectrum. Describe how interference can distort and weaken a wireless signal. Describe the Frequency-Hopping Spread Spectrum (FHSS) and Direct-Sequence Spread Spectrum (DSSS) spread spectrum technologies. Define and explain the multiple-input and multiple-output (MIMO) innovation in the 802.11n standard. Explain the advantages it provides. Describe what an administrator can do if during a wireless router configuration, something goes awry. Explain how residential Worldwide Interoperability for Microwave Access (WiMAX) is installed. Explain how the satellite Internet access service known as a satellite return arrangement works.
How does implementing VoIP assist in centralizing voice and data network management? Describe five features unique to Internet protocols (IP) telephones.
Explain the issue regarding the need for electric current that IP telephones face. Besides being extremely mobile, describe another advantage to softphones. Describe six functions performed by signaling protocols. Explain why media gateway controllers (MGCs) are especially advantageous on large VoIP networks.
Explain how gateways on a converged network exchange and translate signaling and control information with each other so that voice and video packets are properly routed through the network.
Explain why user datagram protocol (UDP) is preferred over Transmission Control Protocol (TCP) for real-time applications such as telephone conversations and Video conferences. Describe the RTP, defined in Request for Comments (RFC) 3550 by the Internet Engineering Task Force (IETF).
Explanation / Answer
Frequency-Hopping Spread Spectrum (FHSS) and Direct-Sequence Spread Spectrum (DSSS)
One specific implementation of spread spectrum is FHSS (frequency hopping spread spectrum). In FHSS transmission, a signal jumps between several different frequencies within a band in a synchronization pattern known only to the channel’s receiver and transmitter. Another type of spread- spectrum signaling is called DSSS (direct-sequence spread spectrum). In DSSS, a signal’s bits are distributed over an entire frequency band at once. Each bit is coded so that the receiver can reassemble the original signal upon receiving the bits.
In 2001, IEEE standardized a new wireless technology under its 802.16 (wireless MAN) committee. Since that time, IEEE has released several versions of the 802.16 standard. Collectively, the 802.16 standards are known as WiMAX, which stands for Worldwide Interoperability for Microwave Access, the name of a group of manufacturers, including Intel and Nokia, who banded together to promote and develop 802.16 products and services. WiMAX was envisioned as a wireless alternative to DSL and T-carrier services for homes and businesses. It achieves much faster throughput than T-carriers at a lower cost for end users.
VoIP assist in centralizing voice and data network management
Video-over-IP signaling and transport protocols, including SIP, H.323, and RTP Understand QoS (quality of service) assurance methods
critical to converged networks, including RSVP and DiffServ Terminology IP Telephony IP telephony (VoIP)
• Any network carrying voice signals using TCP/IP Public or private
• Runs over any packet-switched network VoATM (voice over ATM) VoDSL (voice over DSL) Data connection types carrying VoIP signals
• T-carriers, ISDN, broadband cable, satellite connections, WiFi, WiMAX, cellular telephone networks IP Telephony Internet telephony
• VoIP relies on Internet
• Advantage: breadth and low cost Private lines can also carry VoIP calls
• Effective and economical
• Network congestion control capabilities Better sound quality Non-Data Applications Other non-data applications on converged networks
• FoIP (Fax over IP)
• IPTV (IP television)
• Videoconferencing Multiple participants communicate and collaborate via audiovisual means
• Streaming video Compressed video delivered in continuous stream Hulu.com for free Internet TV shows
• Webcasts Streaming videos supplied via the Web Terminology 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.
Gateways on a converged network exchange and translate signaling and control information with each other so that voice and video packets are properly routed through the network.
Gateways rely on an intermediate device known as an MGC (media gateway controller). As its name implies, an MGC is a computer that manages multiple media gateways. This means that it facilitates the exchange
of call signaling information between these gateways. It also manages and disseminates information about the paths that voice or video signals take between gateway.
In VoIP, audio samples are placed into data packets for transmission over the IP network. Typically, a single packet will contain anywhere from 10-30 milliseconds of audio. TCP and UDP are two of the most commonly used connection protocols used for data traversal across the Internet.
Transmission Control Protocol (TCP)
Transmission Control Protocol or TCP is connection oriented, which means that a formal connection between two end points must be established before any data is transmitted. TCP guarantees the delivery of data, and it also guarantees that data packets will be delivered in the same order in which they were sent.
User Datagram Protocol (UDP)
User Datagram Protocol or UDP is quite different. Unlike TCP, UDP is connectionless, which means that data packets can be sent without warning, preparation, or negotiation. There’s no handshake or setup, just packets of data. UDP also lacks any kind of error control. Not only can packets be delivered in an incorrect order, but they can also get completely left out. UDP is meant for applications where you are more concerned with keeping the stream of information going than making sure you receive every single packet. This makes UDP ideal for real-time services such as Voice over IP.
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