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1.05 Broadband Terminology

(Asynchronous Transfer Mode) A method used for transmitting voice, video, and data over high-speed networks. ATM uses continuous bursts of fixed length packets called cells to transmit data. Commonly referred to as the "ATM Cloud"

by srtrench See Profile edited by KeysCapt See Profile
last modified: 2004-02-09 13:37:45

Bridged tap or bridge tap is a long-used method of cabling for telephone lines. One cable pair (of wires) will "appear" in several different terminal locations (poles or pedestals). This allows the telephone company to use or "assign" that pair to any subscriber near those terminal locations. Once that customer disconnects, that pair becomes usable at any of the terminals. In the days of party lines 2, 4, 6, or 8 customers were commonly connected on the same pair which appeared at several different locations.

DSL can be affected by bridged tap. It depends on where the bridged tap is located ... the farther away from the customer's location, the better.
DSL signal reflects back through the cable pair from the end of a bridged tap, much like a tennis ball against a brick wall. The deflected signal is now out of phase and mixed with the original. The modem receives both signals and gets confused. This is when you "take errors" or cannot sync. If the bridged tap is long, by the time the signal bounces back, the original signal is far ahead and more powerful. Therefore, the modem will ignore the weaker signal and shows no problems.

Almost every cable pair in the world has bridged tap on it, so it definitely isn't always a DSL killer.
--------------------------
This FAQ entry updated by nunya01

by nobody7 See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 11:33:43

In data communications, bits per second (abbreviated bps) is a common measure of data speed for computer modem and transmission carriers. As the term implies, the speed in bps is equal to the number of bits transmitted or received each second. The bandwidth of a signal depends on the speed in bps.

Feedback received on this FAQ entry:
  • windows xp/vista 32bit

    2009-02-15 22:39:17 (st45pc See Profile)



by Retired6 See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 11:33:09

CAP and DMT are two different "flavors" of DSL. CAP uses two channels to connect and DMT uses 256 channels to connect, giving it a greater connection range and making it easier for it to adapt to certain line issues.

by traecysmom See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 11:35:38

In frame relay networks, a committed information rate (CIR) is a bandwidth (expressed in bits per second) associated with a logical connection in a permanent virtual circuit (PVC). Frame relay networks are digital networks in which different logical connections share the same physical path and some logical connections are given higher bandwidths than others. Because the CIR is defined in software, the network's mix of traffic bandwidths can be redefined in a relatively short amount of time.

by Retired6 See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 11:36:04

Pronounced see-lek. A Competitive Local Exchange Carrier is a telephone company that competes with an Incumbent Local Exchange Carrier (ILEC).

With the passage of the Telecommunications Act of 1996, there has been an explosion in the number of CLECs. The Act allows companies with CLEC status to use ILEC infrastructure.

Also see /faq/6789.

by KyleC See Profile edited by KeysCapt See Profile
last modified: 2004-02-02 03:56:37

Customer Premise Equpment. This is the router or DSL modem that connects your PC, to your DSL line. The CPE is usually bundled with your DSL line. CPE may require (but not include) a NIC. (Network Interface Card).

edited by KeysCapt See Profile
last modified: 2004-01-02 11:37:11

A Digital Subscriber Line Access Multiplexer (DSLAM) is a network device, usually at a telephone company central office, that receives signals from multiple customer Digital Subscriber Line (DSL) connections and puts the signals on a high-speed backbone line using multiplexing techniques. Depending on the product, DSLAM multiplexers connect DSL lines with some combination of asynchronous transfer mode (ATM), frame relay, or IP networks. DSLAM enables a phone company to offer business or homes users the fastest phone line technology (DSL) with the fastest backbone network technology (ATM).
Also check : »webopedia.internet.com/TERM/D/DSLAM.html

by Dimension8 See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 11:39:36

Data Link Connection Identifier)

The number of a private or switched virtual circuit in a frame relay network. Located in the frame header, the DLCI field identifies which logical circuit the data travels over, and each DLCI has a committed information rate (CIR) associated with it. The DLCI number is local to the FRAD and frame relay switch it connects to, and it is generally changed by the switch within the network, because the receiving switch uses a different DLCI for the same connection.

by urbman See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 11:38:19

The domain name system (DNS) is the way that Internet domain names are located and translated into Internet Protocol addresses. A domain name is a meaningful and easy-to-remember "handle" for an Internet address.

Feedback received on this FAQ entry:
  • how can i find my dns servers

    2008-12-21 15:15:32



by Retired6 See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 11:37:58

Download is the process of information coming from someplace else to you. When you browse to a web page, you are "downloading" that page. When you get a file from some place on the internet, you are downloading that file.
Upload is the process of sending information from your computer onto the internet. The most common upload for most users is the simple request to "download" a new web page.
--
submitted by 2kmaro

by KeysCapt See Profile
last modified: 2004-01-02 11:38:59

Historically, the wire that "drops" from a telco pole. For DSL, the terminal point of the DSL line outside the building or premise.

edited by KeysCapt See Profile
last modified: 2004-01-02 11:40:00

An End User License Agreement (EULA) is a legal contract between a software application author or publisher and the user of that application. The EULA, often referred to as the "software license," is similar to a rental agreement; the user agrees to pay for the privilege of using the software, and promises the software author or publisher to comply with all restrictions stated in the EULA.

by Retired6 See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 11:42:30

Often a CLEC reports the ILEC has 'facilities' issues and cannot provide an F1 pair to the CLEC. F1 (first facility) pairs refer to the usually buried pair bundles which go from the Central Office to the Cross Box. F2 cables (second facility) are the ones usually aerial, that leave cross boxes.

by Kangaroo8 See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 11:41:14

A distributed filter, or micro-filter, is a small electronic component that fits between your phone line and a regular voice device, such as a phone, a fax, or any device with a regular modem such as a cable box, alarm system or digital TV.

When DSL (ADSL) is provided over voice lines, all devices in the house except the DSL modem must be connected through filters. The filter protects the phone devices from high frequency noise. They are low-pass filters. The filter is also there to protect the DSL signal from being contaminated by high frequency noise added by analog phone devices, answering machines, etc.
--
Above by 2kmaro See Profile


Note: rcnetguy See Profile reports a problem with filters when a power strip is used:
said by rcnetguy:
We had tried to set someone up with DSL and they had no connectivity b/c they set up the filter into the power strip. We set the line away from the strip and it worked just fine.


by KeysCapt See Profile
last modified: 2004-01-05 14:40:06

Firm Order Commitment. The date at which outside wiring is scheduled (and the order becomes "real"). The normal procedure for a DCLEC DSL install, is for the Telco to schedule a FOC date to your MPOE (minimum point of entry). The ISP should advise you of your FOC date, (if one is required), as you may have to be there to let them have access.

Feedback received on this FAQ entry:
  • MPOE also means the "Main" Point Of Entry, the location in your premises where the lines come in from the outside world int your equipment room, etc.

    2012-04-02 11:15:38



edited by KeysCapt See Profile
last modified: 2004-01-02 11:43:20

A fractional T-1 or T-3 line is a T-1 or T-3 digital phone line in the North American T-carrier system that is leased to a customer at a fraction of its data-carrying capacity and at a correspondingly lower cost. A T-1 line contains 24 channels, each with a data transfer capacity of 64 Kbps. The customer can rent some number of the 24 channels. The transmission method and speed of transfer remain the same.

by Retired6 See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 11:46:34

Frame Relay is a high-performance WAN protocol that operates at the physical and data link layers of the OSI reference model. Frame Relay originally was designed for use across Integrated Services Digital Network (ISDN) interfaces. Today, it is used over a variety of other network interfaces as well.

Frame Relay is an example of a packet-switched technology. Packet-switched networks enable end stations to dynamically share the network medium and the available bandwidth. The following two techniques are used in packet-switching technology:

Variable-length packets

Statistical multiplexing

Variable-length packets
are used for more efficient and flexible data transfers. These packets are switched between the various segments in the network until the destination is reached.

Statistical multiplexing techniques control network access in a packet-switched network. The advantage of this technique is that it accommodates more flexibility and more efficient use of bandwidth. Most of today's popular LANs, such as Ethernet and Token Ring, are packet-switched networks.

by Retired6 See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 11:45:49

FTP - File Transfer Protocol

A method of server and obtaining files to and from the internet.
Common FTP software include CuteFTP and WSFTP.

by whatever8 See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 11:46:53

The ground block is where the coax cable from the Cable Company attaches to your house.

It generally should be near your power meter, and grounded to it (to prevent lightning from coming in through the cable line).

Usually, anything after the ground block is your responsibility. The ground block itself and anything before it is the cable company's responsibility.

It is illegal to unground the ground block. Most utility companies will put a bright yellow tag saying that the line MUST be grounded and to call them if you have to make any changes to it.



by KeysCapt See Profile

A high pass filter is a tiny device attached to your cable line to block anything below a certain frequency. A 50MHz HPF would block anything below 50Mhz.

This can be used to prevent very low frequency interference, or to block unauthorized cable modems from attempting to contact the head end, or even to remove TV service from your line while leaving HSD up.

For example, if your cable modem is to talk back to your provider at 29.5Mhz, and this HPF was on your line, your provider would never hear it, because it's below 50Mhz.

If you are having interference on your TV channels while online, try putting a HPF on the TV lines at the splitter. Do NOT filter your cable modem line or you will kill your connection.



I've seen HPFs that run from 50MHz up to 550Mhz.

Feedback received on this FAQ entry:
  • I just have to thank you, I have doing a little research because the cable company turn off my service out of the blue then came out and said they had to hook one of those (EHP, EMHP Highpass Filters 50.0) on my line in the house because my TV was interfering with their system. First real info that make sense on your site. Still don't believe my TV is causing issues with their system, they said it was causing issues with their internet system. BS I am sure, guessing they just wanted to block some channels or something.

    2009-09-27 05:57:09

  • This article refers to cable internet but the article itself is categorized under a DSL FAQ. Shouldn't the article contain ADSL, not coax, filter information?

    2009-03-06 01:25:26



by KeysCapt See Profile

Pronounced eye-lek. Short for incumbent local exchange carrier. An ILEC is a telephone company that was providing local service when the Telecommunications Act of 1996 was enacted. For example: GTE, SWB, AT&T. See also /faq/6788.

by KyleC See Profile edited by KeysCapt See Profile
last modified: 2004-02-02 03:56:00

Internet Message Access Protocol (IMAP) is a standard protocol for accessing e-mail from your local server. IMAP (the latest version is IMAP4) is a client/server protocol in which e-mail is received and held for you by your Internet server. IMAP requires continual access to the server during the time that you are working with your mail.

by Retired6 See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 11:58:09

Kbps stands for kilobits per second (thousands of bits per second) and is a measure of bandwidth (the amount of data that can flow in a given time) on a data transmission medium.

Higher bandwidths are more conveniently expressed in megabits per second (Mbps, or millions of bits per second) and in gigabits per second (Gbps, or billions of bits per second).

by Retired6 See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 11:59:10

LAN stands for "local area network" & is a group of computers and associated devices that share a common communications line or wireless link and typically share the resources of a single processor or server within a small geographic area (for example, within an office building).

Usually, the server has applications and data storage that are shared in common by multiple computer users. A local area network may serve as few as two or three users (for example, in a home network) or many as thousands of users.

by Retired6 See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 12:01:00

LATA (local access and transport area) is a term in the U.S. for a geographic area covered by one or more local telephone companies, which are legally referred to as local exchange carriers (LECs).

A connection between two local exchanges within the LATA is referred to as intraLATA. A connection between a carrier in one LATA to a carrier in another LATA is referred to as interLATA.

InterLATA is long-distance service.

by Retired6 See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 12:01:22

For a terrific explanation of latency, see »DSL FAQ »Latency versus Bandwidth - What is it?

Feedback received on this FAQ entry:
  • Fixed the link. Thanks for that feedback.

    2010-03-16 20:22:46 (KeysCapt See Profile)

  • How do I see a FAQ by number. "Latency?" says to see FAQ 694. A search for 694 doesn't find the FAQ.

    2010-03-16 13:16:15



by KeysCapt See Profile
last modified: 2010-03-16 20:22:08

DC Taps are special types of splitters that lose a ton of signal on one leg, but very little on another. The model number generally determines how great the larger loss number is.

For example:

DC-4 Tap: Loses 4db on one leg, around 1db on the other.
DC-6 Tap: Loses 6db on one leg, around 1db on the other.
DC-9 Tap: Loses 9db on one leg, around 1db on the other.

These splitters have one leg labeled "tap", and the other "out". The "tap" leg is the one with a large amount of loss.

by jav6 See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 12:01:52

Loading coils are used to extend the range of a local loop for voice applications. They are inductors added in series with the phone line which compensate for the parallel capacitance of the line.

They benefit the frequencies in the high end of the voice spectrum at the expense of the frequencies above 3.6kHz.

Thus, loading coils significantly distort xDSL frequencies and must be removed for any DSL operation. They are often found at loops extending farther than 12,000 ft.

by nobody7 See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 12:02:39

In telco, a local loop is the wired connection from a telephone company's CO (central office) in a locality to it's customers' telephones at homes and businesses.

This connection is usually on a pair of copper wires called twisted pair. The system was originally designed for voice transmission only using analog transmission technology on a single voice channel. Today, your computer's modem makes the conversion between analog signals and digital signals.

With Integrated Services Digital Network (ISDN) or Digital Subscriber Line (DSL), the local loop can carry digital signals directly and at a much higher bandwidth than they do for voice only.

by Retired6 See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 12:03:20

Mbps stands for "megabits per second" and is a measure of bandwidth on a telecommunications medium. Depending on the medium and the transmission method, bandwidth is sometimes measured in the Kbps (thousands of bits or kilobits per second) range or the Gbps (billions of bits or gigabits per second) range.

Feedback received on this FAQ entry:
  • 1.Re speed measure and Kbps, Mbps, Gbps - when you say "thousand bits" do you mena 1000 or 1024? So is 1.0 Kbps 1000 bits per second or 1024 bits per second? 2.Do you include start/stop bits in the bit count when speaking in bytes, i.e., are there 8 or 9 or 10 bits in a byte?

    2010-03-16 13:10:55



by Retired6 See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 12:03:47

MPOE (Minimum Point Of Entry)

Local Carriers are responsible for bringing lines to the Minimum Point Of Entry (MPOE) for multi-dwelling business, high-rise, and apartment buildings. If the line is brought to the MPOE by the local carrier (ILEC - Incumbent Local Exchange Carrier), the CLEC (Competitive Local Exchange Carrier) is responsible for finding and wiring an available pair from the MPOE to the Customer Premise Equipment (CPE, AKA Router) location.

MPOE's are also referred to as NIDs and DMARCs.

by FlameBait See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 12:04:02

Noise may be defined as the combination of unwanted interfering signal sources whether it comes from crosstalk, radio frequency interference, distortion, or random signals created by thermal energy. Noise impairs the detection of the smallest analog levels which may be resolved within the demodulator. The noise level along with the maximum clip level of an analog signal path set the available amplitude dynamic range.

The maximum data rate of a modem is limited by the available frequency range (bandwidth) and signal-to-noise ratio (SNR) which is amplitude dynamic range. If more of either is available, more bits may be transferred per second. In an audio analogy, the better (higher) the signal-to-noise ratio is, the easier it is to 'hear' the desired signal above the noise. The same principle applies here. The better the margin (the difference between the signal and the noise) the easier it is for your modem to pick out the DSL signal from the background noise.

by Mike See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 12:04:39

PING: A protocol (command) that sends a message (packet) to another computer and waits for acknowledgment, often used to check if another computer (host) on a network is reachable.

It has been said that PING stands for "Packet Internet Gopher"

by whatever8 See Profile edited by KeysCapt See Profile
last modified: 2011-04-12 13:47:26

POTS stands for Plain Old Telephone Service.
Is sometimes used in talking about Upgrading/Testing your POTS line to support DSL.

by DelaWhere_Steve See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 12:07:41

Point To Point Protocol over Ethernet
and
Point To Point Protocol over ATM

These are different VC Encapsulations. They differ in some ways (the most important is that PPPoA allows for MTUs of 1500), but there is mostly no difference in speed between the two.

Here's a more in-depth discussion, although relative to BellSouth, but good info: /faq/1416

by KeysCapt See Profile
last modified: 2004-01-02 12:09:43

Short for Public Switched Telephone Network, which refers to the international telephone system based on copper wires carrying analog voice data. This is in contrast to newer telephone networks base on digital technologies, such as ISDN and FDDI.

Telephone service carried by the PSTN is often called plain old telephone service (POTS).

by joey911 See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 12:10:34

Permanent virtual circuits (PVC's) are permanently established connections that are used for frequent and consistent data transfers between DTE devices across the Frame Relay network. Communication across a PVC does not require the call setup and termination states that are used with SVCs. PVCs always operate in one of the following two operational states:

Data transferData is transmitted between the DTE devices over the virtual circuit.

IdleThe connection between DTE devices is active, but no data is transferred. Unlike SVC's (Switched Virtual Circuits), PVC's will not be terminated under any circumstances when in an idle state.

by Retired6 See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 12:06:22

QoS stands for "Quality of Service" & is the idea that transmission rates, error rates, and other characteristics can be measured, improved, and, to some extent, guaranteed in advance.

QoS is of particular concern for the continuous transmission of high-bandwidth video and multimedia information.

by Retired6 See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 12:10:54

A Remote DSLAM is an extension of the DSLAM in your CO (Central Office). It acts like an amplifier, in a sense. So, the same copper loop length restrictions apply to that Remote..(depending on the gauge of wire within the facilities)..the service envelope from that remote would be 18kft out (24 ga wire) or 15.5kft out (26 ga wire)

by KeysCapt See Profile
last modified: 2004-01-02 12:11:11

In telecommunication networks, a repeater is a device that receives a signal on an electromagnetic or optical transmission medium, amplifies the signal, and then retransmits it along the next leg of the medium.

A series of repeaters make possible the extension of a signal over a distance. Repeaters are used to interconnect segments in a local area network (LAN).

by Retired6 See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 12:12:42

A Remote Terminal (RT) is fiber fed extension of the central office bringing the capabilities of the central office closer to customers. The remote terminals use next-generation digital loop carriers (Litespan, SLC, Urban, Optera) to provide high-speed data services and traditional telephone service to additional customers, typically those who live farther than a two or three-mile radius of a central office. Remote terminals take many forms including Cabinets, CEV's and Hut's. One example of widespread deployment of RTs is SBC's Project Pronto.

by linetech7 See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 12:13:04

SMDS is a high-speed, packet-switched, datagram-based WAN networking technology used for communication over public data networks (PDNs). SMDS can use fiber or copper-based media.

It supports speeds of 1.544 Mbps over Digital Signal level 1 (DS-1) transmission facilities, or 44.736 Mbps over Digital Signal level 3 (DS-3) transmission facilities.

In addition, SMDS data units are large enough to encapsulate entire IEEE 802.3, IEEE 802.5, and Fiber Distributed Data Interface (FDDI) frames.

by Retired6 See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 12:14:02

The vast majority (possibly all) DSL lines are rated at their sync rate. Since DSL runs over atm/frame relay, it is very important that your DSL modem or router and the DSLAM (the device that takes data from your modem and transmits it onto your ISP's network and vice versa) use a common frame size and frame rate. Your sync rate is only really affected by one thing: Packet loss. DSL companies in 99.9% of cases guarantee only the sync rate on residential lines. This is also why providers will never give you the maximum amount of speed you can theoretically receive. Since there are really no factors that affect sync rate on a regular basis they can do this.

The reason you never achieve your sync rate is because of latency and the internet. Once the signal is off of your local telco line, then it is affected by MANY MANY other things. There have been many good descriptions of how latency and the internet work. If you want more information, then check this out.

»/speed

by dvankuren See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 12:15:17

The TLS protocol provides communications privacy over the Internet. The protocol allows client/server applications to communicate in a way that is designed to prevent eavesdropping, tampering, or message forgery.

by Retired6 See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 12:19:18

Training the line comes from the days of analog modem connections. Remember the long sequence of hisses, beeps, and just some other plain wierd sounds after the dialing of the modem?

Training the line means to negotiate the best possible speed on the line. Sometimes, line noise can interfere with normal DSL line traffic, so, the modem must negotiate the best possible speed despite the noise.

With the noise, the best speed can't be offered, so, it throttles the speed back through a negotiation sequence so that you can get the best speed and connection stablility despite the noise.

by trparky See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 12:22:54

A trouble ticket is an official complaint to the Tech Support department because standard troubleshooting via the phone or e-mail has not corrected the problem.

The life of a trouble ticket:

Once the mainstream Tech Support representative has exhausted all the things they can do by just talking, they submit a "trouble ticket" to someone who has more resources to correct the problem.

Once a trouble ticket is inserted in the pool, it must wait for an engineer to open the complaint. Once the ticket is open, the engineer then diagnoses the problem, and then checks all the ISP's settings, hardware, etc. that could relate to the issue. Once something has been discovered or done, the engineer makes a note into the ticket.

The note in the ticket is a comment from the engineer that states what he has found and what could be done to solve the issue (if not solved already).
At this point, the ticket is closed. Usually the ISP contacts the customer stating the results of the trouble ticket and asks for confirmation that the problem has been corrected. If the issue has been resolved, it's archived into your account details. If it hasn't, either the ticket goes back into the pool to re-check or a tech is dispatched to your location to check the physical end of the customer's side. Once the tech reports after the session has been completed, the ticket is then closed and everyone is happy again.

by Mike See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 12:23:23

This basically shows how much signal the HEAD END is getting compared to noise. The higher this number is, the better. As this number goes down, it means there is more and more noise in the line.

Usually this is caused by bad shielding, R59 cabling, or bad connectors/wall plates. It's not easy to determine the location of interference.

Upstream interference means that the head end is getting a lot of noise around the frequency that your cable modem broadcasts at (15 to 50Mhz). Troubleshoot this just like you would "fuzzy LOW channels".

Feedback received on this FAQ entry:
  • This appears to have nothing to do with DSL, but instead it talks about cable modems, Coax cabling, and 15-50 Mhz. DSL Upstream Signal (to Noise Ratio), in contrast, is low frequency -- 30-140 kHz, and sometimes a real mystery, since it can be unexpectedly high. Sometimes it can be false DSLAM readings, as with IKNS Remote line cards. Since Upstream frequencies are lower, upstream signal loss should be less and US SNR should be greater. But often it is not so at all. A DSL-specific section to this (apparently) DSL-specific FA! would seem to be very helpful.

    2009-05-05 16:14:07 (planiwa See Profile)



by KeysCapt See Profile

A virtual private network (VPN) is a way to use a public telecommunication infrastructure, such as the Internet, to provide remote offices or individual users with secure access to their organization's network. A virtual private network can be contrasted with an expensive system of owned or leased lines that can only be used by one organization. The goal of a VPN is to provide the organization with the same capabilities, but at a much lower cost.

A VPN works by using the shared public infrastructure while maintaining privacy through security procedures and tunneling protocols such as the Layer Two Tunneling Protocol (L2TP). In effect, the protocols, by encrypting data at the sending end and decrypting it at the receiving end, send the data through a "tunnel" that cannot be "entered" by data that is not properly encrypted. An additional level of security involves encrypting not only the data, but also the originating and receiving network addresses.

by Retired6 See Profile edited by KeysCapt See Profile
last modified: 2004-01-02 12:24:22

You can explore an extensive list of terms and definitions related to broadband HERE.

by KeysCapt See Profile
last modified: 2005-07-08 16:08:01

-Hz stand for Hertz. A measurement of frequency in cycles per second. One Hertz is one cycle per second.

-KHz stand for KiloHertz. It is equal to 1000Hz.

-MHz stand for MegaHertz. 1 MegaHertz is equal to 1 000 000 Hz or 1000 KHz.

Feedback received on this FAQ entry:
  • error 1 KHz equals 1000Hz not 1000MHz

    2007-12-02 21:15:48 (vsoldcrow See Profile)



by stephen d8 See Profile edited by KeysCapt See Profile
last modified: 2007-12-02 21:17:00

One MBaud is equal to 1,000,000 symbols of information per second.

by stephen d8 See Profile edited by KeysCapt See Profile
last modified: 2005-12-09 07:25:29

-Shielded cables has protected againt parasites and line interference. It is protected by a coating of aluminum, copper, or other materials.

-Unshielded cables have no protection against any parasite of interference.

by stephen d8 See Profile edited by KeysCapt See Profile
last modified: 2005-12-09 07:26:41

Very-high-bitrate DSL (VDSL or VHDSL)[1] is a DSL technology providing faster data transmission (up to 52 Mbit/s downstream and 16 Mbit/s upstream)[2] over a single flat untwisted or twisted pair of copper wires. These fast speeds mean that VDSL is capable of supporting high bandwidth applications such as HDTV, as well as telephone services (voice over IP) and general Internet access, over a single connection. VDSL is deployed over existing wiring used for POTS and lower-speed DSL connections. This standard was approved by ITU in November 2001.

Second-generation systems (VDSL2; ITU-T G.993.2 approved in February 2006) utilize bandwidth of up to 30 MHz to provide data rates exceeding 100 Mbit/s simultaneously in both the upstream and downstream directions. The maximum available bit rate is achieved at a range of about 300 meters; performance degrades as the loop attenuation increases.

Currently, the standard VDSL uses up to 7 different frequency bands, which enables customization of data rate between upstream and downstream depending on the service offering and spectrum regulations. First generation VDSL standard specified both quadrature amplitude modulation (QAM) and discrete multi-tone modulation (DMT). In 2006, ITU-T standardized VDSL in recommendation G.993.2 which specified only DMT modulation for VDSL2.

by OldschoolDSL See Profile edited by KeysCapt See Profile
last modified: 2010-11-29 06:26:01


Also read About DSL for lots more information