HANDS-ON NETWORKING FUNDAMENTALS By PALMER EDITION: 2ND 13 PUBLISHER: CENGAGE IS

Question

HANDS-ON NETWORKING FUNDAMENTALS

            By PALMER

EDITION: 2ND 13

PUBLISHER: CENGAGE

ISBN:   9781111306748

Asynchronous Transfer Mode (QoS Attributes) Refer to page 405

a. High Tolerance

b. Low tolerance (requres transmissions of 100 milliseconds or less)

c. Accuracy is important, and cell loss requires retransmission and lower throughput.

d. Short burst with predictable idle times.

e. Consistent transfer rate and no burst or idle time

f. Traffic occurs in burst, and there is idle time between traffic burst?

g. No cell loss tolerated

h. Lower transfer rates no burst of traffic, low utilization

i. Intermediate transfer rates and long periods of idle time.

j. Extremely low tolerance

k. Tolerance for high cell loss (up to 1 percent) before degradation in quality is noticed

l.  Intermediate tolerance

Match up 3 definitions to their corresponding ATM QoS Attribute. Some definitions can be used more than once.

DSL

List and describe 5 different type of DSL connections?

Which DSL Technology has the fastest Upstream and Downstream?

What woud be some reasons why someone would choose a DSL connection over a ISDN connection?

a. High Tolerance

b. Low tolerance (requres transmissions of 100 milliseconds or less)

c. Accuracy is important, and cell loss requires retransmission and lower throughput.

d. Short burst with predictable idle times.

e. Consistent transfer rate and no burst or idle time

f. Traffic occurs in burst, and there is idle time between traffic burst?

g. No cell loss tolerated

h. Lower transfer rates no burst of traffic, low utilization

i. Intermediate transfer rates and long periods of idle time.

j. Extremely low tolerance

k. Tolerance for high cell loss (up to 1 percent) before degradation in quality is noticed

l.  Intermediate tolerance

Explanation / Answer

DSL technologies (sometimes summarized as xDSL) include:

Asymmetric DSL

Asymmetric types of DSL connections provide more network bandwidth for downloading(from the Internet service provider down to the subscriber's computer) than foruploading in the other direction). By reducing the amount of bandwidth available upstream, service providers are able to offer relatively more bandwidth downstream.

Asymmetric DSL technology is popular in residential DSL services as home Internet users predominately use downstream bandwidth. Typical asymmetric DSL services support 5 Mbps for downloads and 1 Mbps for uploads.

Common forms of asymmetric DSL include:

Symmetric DSL

Symmetric types of DSL connections provide equal bandwidth for both uploads and downloads. Symmetric DSL technology is popular for business-class DSL services as companies often have greater needs for transferring data. Typical symmetric DSL connections support 1.5 Mbps for downloads and uploads.

Common forms of symmetric DSL include:

Other Types of DSL

IDSL is a hybrid DSL / ISDN technology developed along with other types of DSL but rarely used nowadays due to the relatively low speeds (128 Kbps maximum data rate) it supports.

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ADSL is a type of Digital Subscriber Line (DSL) Internet service commonly used in homes. The 'A' in ADSL refers to the unequal distribution network bandwidth between downloads and uploads: ADSL connections provide comparatively more bandwidth for downloads than for uploads.

ADSL is designed to support the typical home user who frequently downloads large amounts of data from Web sites and online networks but uploads relatively less often. ADSL works by allocating a majority of the available phone line frequencies for communication of downstream traffic.

In other respects, ADSL possesses all of the characteristics one associates with DSL, including high-speed service, an "always on" combination of voice and data support, and availability and performance that is limited by physical distance. ADSL is technically capable of at least 5 Mbps, but ADSL customers may experience lower data rates depending on provider and service plan.

Also Known As: Asymmetric Digital Subscriber Line

RADSL is an implementation of ADSL that automatically adjusts the connection speed to adjust for the quality of the telephone line. This feature allows RADSL service to function over longer distances than does ordinary ADSL, an important feature in suburban neighborhoods.

In RADSL, the broadband modem is configured at startup to test the phone line and adjust the data rate. RADSL typically operates at a lower date rate than regular ADSL. Like ADSL, RADSL provides relatively more bandwidth for downloads and less for uploads.

Also Known As: Rate-Adaptive Asymmetric Digital Subscriber Line

VDSL was developed to support exceptionally high-bandwidth applications such as High-Definition Television (HDTV). VDSL is not as widely deployed as other forms of DSL service. However, VDSL can achieve data rates up to approximately 51,840 Kbps, making it the fastest available form of DSL.

To perform at this speed, VDSL relies on fiber optic cabling. VDSL is designed to work more as a business service that uses ATM internetworking rather than as a consumer service that utilizes IP. VDSL supports both voice and data communication on the same line, like other forms of DSL.

Also like most DSL technology, the performance of VDSL depends significantly on the physical distance traversed by wires: Shorter distances mean faster networking. The technology was originally named VADSL ('A' for asymmetric), but VDSL has now been improved and can operate in either symmetric and asymmetric modes.

Also Known As: Very-high-speed Digital Subscriber Line, VADSL, BDSL

SDSL is a form of Digital Subscriber Line (DSL) service that provides equal bandwidth for both uploads and downloads. Originally developed in Europe, SDSL was one of the earliest forms of DSL to not require multiple telephone lines.

SDSL possesses all of the common characteristics of DSL, including an "always on" combination of voice and data services, availability limited by physical distance, and high speed access compared to analog modems. SDSL supports data rates up to 3,088 Kbps.

Also Known As: Symmetric Digital Subscriber Line, Single-line DSL

HDSL technology was developed in the early 1990s, making it one of the oldest forms of DSL. HDSL service provides equal bandwidth for both downloads and uploads, offering data rates up to 2,048 Kbps. Note that HDSL requires multiple phone lines to accomplish this.

Like other forms of DSL, HDSL features "always on" combined voice and data services. HDSL enjoyed some popularity in years past, but the technology has effectively been replaced by alternatives like SDSL that only require one phone line and offer similar performance and reach.

Also Known As: High-data-rate DSL, High-speed DSL

ISDN is a network technology that supports digital transfer of simultaneous voice and data traffic. Similar to DSL in this respect, an ISDN Internet service works over ordinary telephone lines. ISDN Internet service generally supports data rates of 128 Kbps.

ISDN emerged as an alternative to traditional dialup networking during the 1990s. The relatively high cost of ISDN service, though, limited its popularity with residential customers at the outset. More recently, the much higher network speeds supported by newer broadbandtechnologies like DSL have drawn many consumers away from ISDN service.

ISDN technology today has limited applications as a networking solution. Some customers who live in rural areas of the U.S. subscribe to ISDN Internet as an alternative tosatellite Internet. ISDN phone service also remains fairly common in some European countries.

Also Known As: Integrated Services Digital Network

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Integrated Services Digital Network and DSL both offer options for reliably accessing the Internet over telephone lines at rapid speeds. Unlike standard dial-up connections, ISDN and DSL allow you to simultaneously use the telephone and Internet on the same line. They're more frequently available in cities than small towns or rural areas. However, a comparison of ISDN and DSL reveals significant differences in speed, equipment needs, cost and other factors.

EQUIPMENT

DSL and ISDN require special types of modems, usually installed outside of the computer. ISDN equipment typically costs more and requires a special digital telephone line, according to Pacific Bell. With the right external hardware, both types of connections will work with older and newer computers. Internet connection speeds may vary depending upon the capabilities of the computer and networking equipment in use.

SPEED

DSL and ISDN remain fast enough to check email and visit websites quickly. ISDN proves substantially faster than dial-up, making it possible to download files quickly and listen to high-quality streaming audio. ISDN can achieve connections of 128 kilobits per second. However, DSL connections typically operate at 768Kbps or faster. The difference becomes significant with large downloads and high-resolution videos.

TELEPHONE

You can experience different telephone service depending upon whether you have DSL or ISDN. Using a special digital telephone, ISDN provides digitized voice audio rather than the analog audio of standard telephone service used with DSL, according to BellSouth. However, it doesn't work during an electrical outage. DSL lets you to keep all existing telephone equipment, wiring and jacks; this also allows you to use corded telephones during power outages.

EXPENSE

Internet access costs vary significantly depending upon your local area. The National Center for Education Statistics indicates that ISDN typically costs somewhat more than DSL. However, it may cost less, the same or substantially more where you live. It's best to conduct your own comparison of rates offered by different Internet and telephone providers. More companies offer DSL, which promotes competition in prices. Nonetheless, ISDN providers still have to compete with other forms of Internet access.

AVAILABILITY

The local availability of ISDN and DSL do vary, although neither can be found in as many rural areas as cable or dial-up access. ISDN remains available in some areas DSL isn't. However, telephone companies now primarily focus upon expanding DSL. An advantage of ISDN is that you can connect using the same account on different digital phone lines, even during travel, while DSL requires the designation of a single line for Internet access.

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