451:(upload) data, so, download rates are faster than upload rates, because most users download much larger quantities of data than they upload. Because the telephone lines were never designed to carry such high frequency signals, DSL is distance-sensitive. The farther away from the switching center the modem is, the longer the telephone wires, the weaker the signal, and the lower the data rate that the modem can achieve. Users in cities, close to switching centers, may have access to higher rate service, up to 24 Mbit/s. The distance limit for ADSL is 18 000 feet (5.5 km or 3.4 miles). However, other devices installed in telephone lines by the phone company, such as
360:. This capacity is unused in normal phone service. DSL uses these higher frequencies to send digital data between the DSL modem and the local switching center, without interfering with normal telephone service. At the local switching center the data is transferred directly between the customer's phone line and internet lines, so DSL signals do not travel through the telephone network itself. It is not necessary to dial a telephone number to initiate a connection; the DSL connection is "on" whenever the modem is on.
635:
124:
27:
862:
600:), in order not to interfere with voice service which is primarily 0–4 kHz. Voice-band modems use the same frequency spectrum as ordinary telephones, and will interfere with voice service - it is usually impossible to make a telephone call on a line which is being used by a voice-band modem. Because a single phone line commonly carries DSL and voice,
396:
the transmission quality on each channel, and if it is too impaired it will shift the signal to other channels. The modem is constantly shifting data between channels searching for the best transmission rates. Thus interference or poor quality lines will generally not interrupt transmission, but only cause the data rate of the modem to degrade.
395:
to allow minor bit errors due to noise to be corrected at the receiving end. Most of the channels are unidirectional, carrying download data from the DSLAM to the modem, but some on the low frequency end are bidirectional, to carry the smaller quantity of upload traffic. The modem constantly monitors
501:
DSL does not interfere with normal telephone calls on the telephone line, and does not require dialing a telephone number to initiate a connection, it is always "on". A voice-band modem dials a telephone number to initiate a connection, and while it is connected the telephone line cannot be used for
477:
which must be plugged into the phone lines going to all voiceband devices on the same line. The filter blocks all frequencies above 4 kHz, so it blocks the DSL signal while allowing voice frequency signals through. A filter must not be inserted in the phone line going to the DSL modem, because
298:
Many routers provide an internal web page to the local network for device configuration and status reporting. Most DSL routers are designed to be installed by the customer for which a CD or DVD containing an installation program is supplied. The program may also activate the DSL service. Upon
646:
can be integrated onto one chip. Higher levels of integration have benefited DSL just as they benefited other computer hardware. A DSL modem requires the following for its operation; exactly what is on the circuit card and how it is arranged can change as technology improves:
299:
powering the router it may take several minutes for the local network and DSL link to initialize, usually indicated by the status lights turning green. There are also PCI DSL modems, which plug into an available PCI card slot on a computer.
383:. The modem only uses frequencies above 8 kHz, to avoid interfering with normal phone service. The bandwidth of the line between 8 kHz and about 1 MHz is divided into 247 separate channels, each 4 kHz wide. A separate
621:
DSL modems are intended for particular protocols and sometimes won't work on another line even from the same company, while most voice-band modems use international standards and can "fall back" to find a standard that will
593:
provide interfaces similar to those provided for voice-band modems. This is based on the assumption that in the future, as CPU speeds increase, internal DSL modems may become more mainstream.
269:
Ethernet lights - there is usually a light over each
Ethernet jack; a steady (or sometimes flashing) light indicates that the Ethernet link to that computer or device is functioning
473:
To prevent the DSL signal from entering the phone lines into telephones, answering machines, faxes and other devices where it could cause interference, DSL modems come with
626:
Most of these differences are of little interest to consumers, except the greater speed of DSL and the ability to use the telephone even when the computer is online.
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1060:
487:
369:
893:
344:
within that bandwidth, which limited them to a data rate of about 56 kbit/s. However, the copper wires that connect telephones with the local
415:
onto a separate carrier signal and sent through a separate frequency channel over the subscriber's telephone line to the DSL modem. The modem
618:
to which they are wired, which in turn connects them to the
Internet, while most voice-band modems can dial directly anywhere in the world.
372:(DSLAM), which is connected directly to the Internet. The local switching center must be equipped with these devices to offer DSL service.
971:
722:
597:
527:
regard voice-band modems as part of the hardware of the computer, and similarly to other parts of the computer's hardware such as the
555:
given in the router's manual into the browser's address bar, with which various technical changes can be made, such as changing the
514:
313:
280:) so the DSL link over the telephone line is functioning; newer modems that support ADSL2+ bonding will have one light for each line
209:
110:
1143:
380:
48:
607:
DSL modems vary in data speed from hundreds of kilobits per second to many megabits, while voice-band modems are nominally
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886:
376:
333:
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signal carries information in each channel. Thus the system acts like 247 separate modems operating simultaneously. The
91:
171:. The modem connects to a single computer or router, through an Ethernet port, USB port, or is installed in a computer
732:
63:
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of the incoming digital data are split up and sent in parallel over the channels. Each data stream is sent using an
1095:
991:
44:
37:
1100:
70:
543:). DSL modems rarely require manual configuration or attention, but when they do they can be accessed using the
198:, a DSL router usually manages the connection and sharing of the DSL service in a home or small office network.
1075:
1065:
986:
879:
294:
Wireless light - (only in wireless DSL modems) indicates that the wireless network is initialized and working
262:
It usually has a series of LED status lights which show the status of parts of the DSL communications link:
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981:
931:
921:
444:
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DSL light - a steady light indicates that the modem has established contact with the equipment in the local
160:
133:
866:
490:(DSLAM), and receives and demodulates them from the DSLAM. It serves fundamentally the same purpose as the
77:
505:
DSL routers, the most common form of DSL modem, are external to the computer and wired to the computer's
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916:
711:
634:
536:
448:
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248:
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59:
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Apart from connecting to a DSL service, many modems offer additional integrated features, forming a
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port, whereas voice-band modems are usually internal devices installed in the computer itself in a
195:
719:(Domain Name System) caching, a relay or proxy DNS cache which queries DNS servers on the Internet
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404:
349:
273:
183:
152:
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DSL modems transfer data at a rate which is at least 10 to 20 times that of a voice-band modem.
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cables to connect it to computers or printers, creating a local network. It usually also has a
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341:
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345:
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252:
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The device at the local switching center which communicates with the DSL modem is called a
1148:
902:
782:
673:
474:
423:, puts the data together again in the proper order, and sends it to the computer over the
353:
329:
941:
802:
743:
528:
440:
325:
231:
jack to connect to a standard subscriber telephone line. It has several RJ45 jacks for
156:
84:
443:(ADSL). The "asymmetric" means that more of the bandwidth of the line is dedicated to
1132:
667:
494:
that was a mainstay in the late 20th century, but differs from it in important ways.
491:
400:
123:
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1021:
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651:
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416:
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For example, when downloading a web page, the packets of web page data travel over
388:
384:
411:. At the DSLAM they are split into as many as 247 parallel data streams. Each is
291:
protocol are initialized and working, so the system is connected to the
Internet
26:
601:
552:
468:
456:
412:
284:
832:
356:, are actually able to carry a much wider band of frequencies, up to several
1011:
966:
608:
532:
459:, block the signal, and may disqualify a given phone line from DSL service.
357:
321:
256:
240:
201:
Different DSL routers and modems support different DSL technology variants:
419:
the carrier, extracting the data stream from each carrier signal, performs
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it would block the communication between the modem and switching center.
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232:
187:
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is a standalone device that combines the function of a DSL modem and a
539:. In contrast, DSL routers are regarded as separate nodes in the LAN (
1080:
951:
926:
656:
Data connection and power circuitry (for example, USB, Ethernet, PCI)
596:
DSL modems use frequencies from 25 kHz to above 1 MHz (see
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With ADSL, the modem and the DSLAM communicate by a protocol called
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122:
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A DSL modem modulates high-frequency tones for transmission to a
266:
Power light - indicates that the modem is turned on and has power
946:
736:
642:
As technology advances, functions that are provided by multiple
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228:
215:
203:
875:
243:, to allow connection to computers without an Ethernet port. A
759:
716:
567:
510:
236:
20:
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slot in the back. Internal DSL modems are rare but available.
340:
transmitted information through the telephone network with
439:
Most consumer DSL lines use one of several varieties of
186:, and can connect multiple computers through multiple
611:
and actually limited to approximately 50 kbit/s.
247:
DSL router also has antennas to allow it to act as a
239:
jack which can be used to connect to computers via a
1048:
1030:
1002:
909:
407:computer directly to the DSLAM at the neighborhood
283:Internet light - a steady light indicates that the
51:. Unsourced material may be challenged and removed.
16:Type of computer network modem; network equipment
328:from one phone to another, is designed to carry
826:
824:
822:
820:
818:
816:
814:
812:
756:(priority control for data flows between users)
803:"ADSL BONDING | Increase Broadband Speed"
887:
255:. Power is usually supplied by a cord from a
8:
251:, so computers can connect to it forming a
894:
880:
872:
488:digital subscriber line access multiplexer
370:Digital Subscriber Line Access Multiplexer
111:Learn how and when to remove this message
559:'s password, and adjusting the router's
794:
614:DSL modems exchange data with only the
332:signals, and is therefore limited to a
227:A DSL router consists of a box with an
566:For external DSL modems connected by
7:
163:(DSL) service for connection to the
127:Westell Model 6100 AXXDSL DSL router
49:adding citations to reliable sources
723:Dynamic Host Configuration Protocol
638:ADSL modem router internals labeled
604:are used to separate the two uses.
598:Asymmetric Digital Subscriber Line
14:
314:public switched telephone network
860:
25:
578:generally recognize these as a
482:Comparison to voice-band modems
381:frequency division multiplexing
36:needs additional citations for
147:is a device used to connect a
1:
377:discrete multitone modulation
336:of 3.4 kHz. Before DSL,
324:and switches which transmits
750:Voice over Internet Protocol
731:functionality that includes
580:Network interface controller
431:) network by radio signals.
733:Network Address Translation
535:are configured through the
1167:
839:. Discovery Communications
688:
466:
379:(DMT), which is a form of
585:For internal DSL modems,
547:. Routers usually have a
502:normal telephone service.
427:line, or for a wireless (
752:functionality including
735:(NAT) to share a single
551:, accessed by typing an
403:Internet lines from the
167:, which is often called
1144:Digital subscriber line
831:Franklin, Curt (2011).
760:Virtual Private Network
161:digital subscriber line
134:digital subscriber line
639:
128:
869:at Wikimedia Commons
712:wireless access point
689:Further information:
637:
537:Windows Control Panel
447:(download) data than
435:Data rates and access
393:error-correcting code
249:wireless access point
192:wireless access point
190:ports or an integral
126:
670:chip and line driver
45:improve this article
1139:Networking hardware
1049:Long range wireless
778:Residential gateway
746:(typically 4 ports)
697:residential gateway
691:Residential gateway
630:Hardware components
196:residential gateway
159:which provides the
754:quality of service
640:
541:local area network
409:telephone exchange
350:telephone exchange
274:telephone exchange
129:
1126:
1125:
865:Media related to
591:operating systems
587:Microsoft Windows
576:operating systems
572:Microsoft Windows
525:operating systems
521:Microsoft Windows
364:Data transmission
342:audio frequencies
338:voice-band modems
318:switching centers
316:, the network of
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864:
849:
848:
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844:
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807:
806:
805:. March 6, 2014.
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685:Service features
557:wireless network
545:internet browser
492:voice-band modem
475:low pass filters
421:error correction
346:switching center
253:wireless network
194:. Also called a
178:The more common
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903:Internet access
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837:How Stuff Works
833:"How DSL Works"
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783:Registered jack
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674:Microcontroller
632:
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354:subscriber loop
330:voice frequency
326:telephone calls
320:, trunk lines,
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856:External links
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467:Main article:
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441:Asymmetric DSL
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352:), called the
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157:telephone line
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101:September 2013
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725:(DHCP) server
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515:PCI interface
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453:loading coils
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401:optical fiber
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259:transformer.
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169:DSL broadband
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62: –
61:
57:
56:Find sources:
50:
46:
40:
39:
34:This article
32:
28:
23:
22:
19:
1032:Wireless LAN
1022:Wireless USB
1004:Wireless PAN
859:
841:. Retrieved
836:
797:
773:Home network
694:
661:digital data
652:Power supply
641:
625:
509:port or its
485:
472:
438:
398:
374:
367:
311:
297:
261:
244:
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179:
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142:
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132:
130:
107:
98:
88:
81:
74:
67:
55:
43:Please help
38:verification
35:
18:
867:ADSL modems
762:termination
742:A built-in
602:DSL filters
457:bridge taps
417:demodulates
308:DSL concept
223:Description
60:"DSL modem"
1133:Categories
1096:Muni Wi-Fi
987:Power-line
843:August 21,
789:References
609:56K modems
589:and other
574:and other
553:IP address
523:and other
469:DSL filter
445:downstream
322:amplifiers
303:Technology
285:IP address
180:DSL router
71:newspapers
1101:Satellite
1012:Bluetooth
992:Broadband
967:IEEE 1901
533:hard disk
413:modulated
358:megahertz
334:bandwidth
257:wall wart
241:USB cable
1106:UMTS-TDD
957:HomePlug
937:Ethernet
767:See also
739:address.
709:802.11ac
561:firewall
507:Ethernet
449:upstream
425:Ethernet
245:wireless
233:Ethernet
188:Ethernet
173:PCI slot
165:Internet
149:computer
962:HomePNA
922:Dial-up
705:802.11n
549:webpage
463:Filters
385:carrier
85:scholar
1149:Modems
1081:iBurst
952:Nessum
927:DOCSIS
744:switch
729:Router
679:Filter
668:analog
405:server
213:, and
184:router
153:router
87:
80:
73:
66:
58:
1116:WiBro
1111:WiMAX
1056:5G NR
1040:Wi-Fi
1017:Li-Fi
917:Cable
910:Wired
644:chips
622:work.
616:DSLAM
529:mouse
429:Wi-Fi
278:DSLAM
155:to a
144:modem
92:JSTOR
78:books
1091:MMDS
1076:HSPA
1071:GPRS
1066:EVDO
1061:DECT
977:MoCA
972:ISDN
947:G.hn
942:FTTx
845:2012
737:IPv4
666:DSL
663:pump
659:DSL
455:and
389:bits
312:The
289:DHCP
287:and
229:RJ11
216:ADSL
210:SDSL
204:VDSL
64:news
1086:LTE
982:PON
932:DSL
717:DNS
707:or
703:An
568:USB
531:or
511:USB
237:USB
151:or
139:DSL
47:by
1135::
835:.
811:^
699::
570:,
219:.
207:,
175:.
141:)
131:A
895:e
888:t
881:v
847:.
582:.
563:.
348:(
276:(
137:(
114:)
108:(
103:)
99:(
89:·
82:·
75:·
68:·
41:.
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
