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2.1 What is?


ADSL - Asymmetric Digital Subscriber Line
ANSI - American National Standards Institute
ANT - ADSL Network Terminator
ASAM - ATM Subscriber Access Multiplexer
ATM - Asynchronous Transfer Mode
ATU-C - ADSL Termination Unit - Central Office
ATU-R - ADSL Termination Unit - Remote
AUP - Acceptable Use Policy
BBR - BroadbandReports
bps - Bits per Second
Bps - Bytes per Second
BSFA - BellSouth FastAccess
CLEC - Competitive Local Exchange Carrier
CO - Central Office
CPE - Customer Premises (or Provided) Equipment
DEMARC - Telephone Company Line Demarcation Point
DFITL - DSL over Fiber In The Loop
DHCP - Dynamic Host Configuration Protocol
DLC - Digital Loop Carrier
DMT - Discrete Multi-tone
DSLR - DSLReports
DS0 - Digital Signal Level Zero 64kbps
DS1 - Digital Signal Level One 1.544Mbps
DS3 - Digital Signal Level Three 44.736Mbps
DSL - Digital Subscriber Line
DSLAM - Digital Subscriber Line Access Multiplexer
DSU - Data Service Unit
DTE - Data Terminal Equipment
EMI - Electromagnetic Interference (or Induction)
EULA - End User License Agreement
FA - FastAccess
FCC - Federal Communications Commission
FITL - Fiber in the Loop
FTTC - Fiber to the Curb
HDSL - High bit-rate Digital Subscriber Line
IDSL - ISDN Digital Subscriber Line
IEC - Inter-Exchange Carrier
IEEE - Institute of Electrical and Electronics Engineers
IFITL - Integrated Fiber in the Loop
ILEC - Incumbent Local Exchange Carrier
INI - Inside Network Interface
IP - Internet Protocol
ISDN - Integrated Services Digital Network
ISO - International Standards Organization
ISP - Internet Service Provider
kbps - Kilobits per second
KBps - Kilobytes per second
LAN - Local Area Network
LEC - Local Exchange Carrier
Mbps - Megabits per second
MODEM - Modulator Demodulator
MULDEM - Multiplexer Demultiplexer
MUX - Multiplexer
NAT - Network Address Translation
NGDLC - Next Generation Digital Loop Carrier
NIC - Network Interface Card
NID - Network Interface Device
NT - Network Terminator
ONI - Outside Network Interface
ONU - Optical Network Unit
PCM - Pulse Code Modulation
POP - Point of Presence
POTS - Plain Old Telephone Service
PPP - Point to Point Protocol
PPPoA - Point to Point Protocol Over ATM
PPPoE - Point to Point Protocol Over Ethernet
PVC - Private (or Permanent) Virtual Circuit
RBOC - Regional Bell Operating Company
RDSLAM - Remote Digital Subscriber Line Access Multiplexer
RJnnx - Registered Jack (nnx = type)
RT - Remote Terminal
S/N - Signal-to-Noise Ratio
SDSL - Symmetric Digital Subscriber Line
SLC - Subscriber Loop Carrier
SNR - Signal-to-Noise Ratio
SOHO - Small Office/Home Office
STH - Alcatel SpeedTouch Home Ethernet Modem
TCP - Transport Control Protocol
TELCO - Telephone Company
USB - Universal Serial Bus
VDSL - Very high bit-rate Digital Subscriber Line
VoIP - Voice Over Internet Protocol
VPN - Virtual Private Network
WAN - Wide Area Network
xDSL - (generic) Digital Subscriber Line



by leevis See Profile edited by KeysCapt See Profile
last modified: 2004-01-31 07:55:54

BBG (BroadBand Gateway) is a generic term given to BellSouth's ATM aggregation network. It combines multiple customers into large ATM tunnels instead of each customer being assigned an individual PVC throughout the entire network to the ISP. There are two types of BBG networks.

    EUA (End User Aggregation)
    EUA was BellSouth's original BBG network and requires two Nortel Shastas (an IBG and EBG) to aggregate the data and build large bandwidth tunnels. It then utilizes an L2TP tunnel to a Redback SMS which is used to terminate the PPP session. Initially, the additional overhead of the L2TP tunnel caused some erratic problems when PPPoE packets fragmented. This original infrastructure is no longer being actively deployed and is almost completely phased out in favor of EEUA.

    EEUA (Enhanced End User Aggreagtion)
    EEUA is a second generation aggregation network and it eliminates many of the original EUA network elements. EEUA utilizes one Nortel Shasta (IBG) that not only acts as an aggregation device but also terminates the PPP session. EEUA eliminates the EBG Shasta, the L2TP tunnel, and the Redback SMS. It provides a more direct route to the ISP's network with less latency and fewer hops.

More information is available below:

BBG EUA Network Diagram
FastAccess Service Specifications
(Appendix B, page 31)

Andy Houtz DSL

by Andy Houtz See Profile edited by FAQFixer See Profile
last modified: 2006-12-21 23:40:35

Important Note:
Although data rates and data storage both use bits, bytes, kilobits, etc, there is an interesting difference. It is generally accepted that when discussing data rates, kilobytes are measured as 1000 bits (not 1024 bits as used in data storage). This FAQ is specifically for data rates only.

Bits and Bytes are binary data units.

Bits:
Bits are the smallest binary data unit. A bit can only represent two binary values (1 or 0)

kilobit = 1000 bits
Megabit = 1000 Kilobits

Bytes:
A byte is a combination of 8 bits. One byte can represent 256 binary values (any number between 0-255).

Kilobyte = 1,000 bytes
Megabyte = 1,000,000 bytes
Gigabyte = 1,000,000,000 bytes

Important Note:
BellSouth advertises their speeds in bits/second not bytes/second:
Lite is 768 kilobits/second (Kbps) or approximately 96 kilobytes/second
Ultra is 1472 kilobits/second (Kbps) or approximately 184 kilobytes/second
Extreme 3.0 is 3000 kilobits/second (Kbps) or approximately 375 kilobytes/second
Extreme 6.0 is 6000 kilobits/second (Kbps) or approximately 750 kilobytes/second

Bit to Byte Calculations:
You can divide your speed (kilobits) by 8 to get your kilobytes or use this handy calculator tool for converting these measurements.



Andy Houtz DSL

by Andy Houtz See Profile edited by FAQFixer See Profile
last modified: 2009-01-03 14:20:07

Bridging is a common networking term used to describe the process of integrating two different networks or topologies. When speaking specifically about DSL routers/modems, Bridged Ethernet describes the process of integrating and converting the DSL signal from the TelCo side into an Ethernet signal from your computer/network. All DSL modems/routers must do this basic Physical and Data Link bridging, but they typically also perform other higher functions such as PPPoX, Routing, NAT, etc. When you configure a modem/router for "Bridged Ethernet" it no longer controls the higher functions and is nothing more than a glorified DSL to Ethernet converter.

Due to its simplicity "Bridged Ethernet" is the preferred method method to use when you are integrating another router in the network. "Bridged Ethernet" ensures that the DSL modem is only performing the DSL to Ethernet conversion so that the other router can perform the higher functions.

Configuring Bridged Mode for a Motorola 2210
Configuring Bridged Mode for a Westell 2100/2200/6100

by FAQFixer See Profile

A bridged tap is an unterminated section of wire that can interupt or create disturbances on a transmission wire. It sometimes involves a technique for a telephone install that taps you into a line that runs past your house, rather than terminating directly to your house. The line doesn't neccesarily go to any other customer premises, it just ends.

The phone company can simply add a tap up or down to service wire whenever customers move or a change in service is needed. Unfortunately, you have unterminated phone line running up the road ready to pick up any interference, like a huge TV antenna. Because it's not terminated properly, the signals are reflected and bounce up and down the line and can reinforce or cancel the signals your equipment is trying to send to your ISP.

by leevis See Profile edited by Andy Houtz See Profile
last modified: 2004-04-10 00:54:03

CO is an acronym for Central Office, a physical building where the local telephone switching equipment is located. Lines running from a subscriber's home connect to the local central office.

by leevis See Profile edited by KeysCapt See Profile
last modified: 2004-01-31 08:45:40

CRC is a method of detecting errors in data transmission. A CRC is information sent within a block of data that is checked by the receiving end to verify if data was all received correctly. A high CRC count in itself is not cause for alarm. However, any substantial increase in CRC errors after your initial connection is established is a problem and usually points to a physical issue somewhere between the modem and the DSLAM. Isolate your inside wiring as a cause by testing from the NID and troubleshoot from there.

Andy Houtz DSL

by FAQFixer See Profile
last modified: 2007-08-23 09:36:50

Certain network devices or equipment must use a crossover cable to function properly. A crossover swaps the transmit and receive pairs. Important Note: A crossover cable is not the same as a reverse polarity cable.





Andy Houtz DSL

by Andy Houtz See Profile edited by FAQFixer See Profile
last modified: 2006-12-21 23:42:18

DAMLs (Digitally Added Main Line) are line multiplexers that are used to provide a second analog telephone line where an additional line is needed, but an extra second wire pair is not available. Many older homes and local loops do not have spare wire pairs and are forced to use a DAML. DAMLs must be removed removed to get DSL.

Andy Houtz DSL

by Andy Houtz See Profile edited by FAQFixer See Profile
last modified: 2006-12-21 23:42:33

DFITL (DSL over Fiber in the Loop) is the latest voice and data service utilizing FTTC (Fiber to the Curb). DFITL uses fiber to the neighborhood, existing copper to the home so it does not require special wiring. Since DFITL data service uses a DSL signal it requires a modem to connect to the internet.

Very Important Service Note:
AT&T is now limiting DFITL customers to the 1.5Mbps service tier. Older customers that currently have 3.0 service are being grandfathered, but all new (or returning) customers are limited to 1.5Mbps.

by DSLDUDE6 See Profile edited by FAQFixer See Profile
last modified: 2009-03-02 19:22:09

DHCP (Dynamic Host Configuration Protocol) is the protocol that automatically assigns each computer an IP address on a network.

Typically, a router negotiates with the computers on the network and then assigns an local IP address to each computer. Additionally, DHCP uses the concept of a lease or amount of time that a given IP address will be valid for a computer. Using very short leases, DHCP can dynamically reconfigure networks in which there are more computers than there are available IP addresses. BellSouth does not use DHCP to assign WAN IP addresses. Click here for more info.

Andy Houtz DSL

by Andy Houtz See Profile edited by FAQFixer See Profile
last modified: 2006-12-21 23:45:21

Digital loop carrier (DLC) is equipment that bundles a number of individual phone line signals into a single multiplexed digital signal for local traffic between a telephone company central office and a business complex or other outlying service area. Typically, up to 24 analog voice calls are combined into a single signal and transmitted over a single copper T-carrier system or E-carrier line, an optical fiber cable, or a wireless connection. In a home, business, or other installation using digital loop carrier, the analog phone lines of individual users are connected to a local DLC box which then converts the analog signals into digital and combines (multiplexes) them into one signal that it sent to the phone company's central office on the single line. At the central office, the combined signal is separated back into the original signals. An estimated 20% of today's telephone users are being served by digital loop carriers.

Digital loop carrier can carry traffic for regular phone calls (plain old telephone service) and Integrated Services Digital Network (ISDN) service. More recently, approaches have been developed for using DLC to handle the higher bandwidth of Digital Subscriber Line (DSL) service.

Digital loop carrier is typically used as an efficient way to provide service to an office building or complex and to extend service to new areas outside the current local loop. DLC is also used to set up telephone service in emergency situations. Customers can easily migrate from a T-1 or E-1 line to fiber optic when it becomes needed and is available.

A basic tutorial is available here.

by Andy Houtz See Profile
last modified: 2004-01-26 09:40:51

DNS is an acronym for Domain Name Server (or Service or System), an Internet service that translates domain names into IP addresses. Everyone is familiar with domain names like www.google.com, however the Internet is actually based on IP addresses, not domain names. Every time you use a domain name a DNS service must translate the name into the corresponding IP address. For example, the domain name www.google.com translates to 64.233.187.104.

The DNS system is, in fact, its own network. If one DNS server doesn't know how to translate a particular domain name, it asks another one, and so on, until the correct IP address is returned.

Andy Houtz DSL

by FAQFixer See Profile
last modified: 2006-12-21 23:45:54

DSLAM is an acronym for Digital Subscriber Line Access Multiplexer. It's the piece of equipment that makes DSL possible. The DSLAM connects many customer lines to one high-speed internet access point. DSLAMs can be located in a CO or in conjunction with an RT (Remote Terminal) to create a Remote DSLAM that entends the reach of service. Click on the links below for pictures of popular DSLAMs.

Alcatel 7300 DSLAM
Siemens High Density DSLAM

by leevis See Profile edited by FAQFixer See Profile
last modified: 2005-12-05 20:31:44

An EBN (Entrance Bridge Network) is the point of demarcation between the Phone Company wiring and the residential wiring. They are usually modular pieces that slip or clip into a NID (Network Interface Device) and provide an RJ-11 test jack for troubleshooting purposes. Several common EBNs are shown separately as well as installed in a NID below.









Andy Houtz DSL

by Andy Houtz See Profile edited by FAQFixer See Profile
last modified: 2006-12-21 23:46:33

Microfilters and/or in-line filters are required on all jacks that have POTS (Plain Old Telephone Service) equipment attached. POTs devices include: phones, cordless phones, CallerID boxes, TeleZappers, fax machines, etc. They isolate the POTS signals from the DSL signals so there is no interference. An assortment of microfilters are shipped with the self-install kit along with your modem. BellSouth's current Self-Install Kit includes 1 wall mount filter and 4 in-line filters. Other common microfilters are also shown below. Microfilters can by purchased online from the BellSouth Order Request Site or at most larger electronics stores like Circuit City, Radio Shack, or Comp USA, BestBuy, etc.

Important Note: Because each filter increases line loss users should not use more than 5 microfilters on their inside wiring. There are active microfilters specifically designed for homes that require more than 5 filters or you should create a homerun with a single dedicated splitter.





Important Installation Note: The BellSouth supplied dual line filters have two outputs. One line out is marked "phone" and is used to connect to all POTS devices. The other line out is marked "ADSL/HPNA" or "Data" and is used to connect the DSL modem. Single line filters are also available and are used when only a single phone (no modem) is connected to that specific wall plate. It is critical that you install the filters correctly. Failure to do so will create poor performance and speeds. It may even keep the modem from synching at all.





Andy Houtz DSL

by Andy Houtz See Profile edited by FAQFixer See Profile
last modified: 2009-02-18 11:47:06

If your home has an alarm it must have some type of filter or splitter to isolate the alarm signal from your DSL. The alarm must be isolated even if the service is not being used. Specialized RJ-31X/RJ-38X alarm filters that easily connect in line, as well as panel type filters are available for direct use with home alarm system. More information is available here. Alarm systems can also be isolated by installing a homerun.

Note: The appearance of these links in no way constitutes any endorsement and they are provided as a convenience only. No representation is made as to the suitability of these or any other commercial links included here.

eBay is a great source for alarm filters at very good prices. Also, several retailers sell to the general public. Please check the following links:

Hometech
Pro-Comm-Online
Amerisponse
LufkinSecurity












Andy Houtz DSL

by Andy Houtz See Profile edited by FAQFixer See Profile
last modified: 2006-12-21 23:46:52

A home run is simply a dedicated line run from the ADSL splitter to a jack serving your ADSL modem. The DSL and POTS signals and wires are separated by a DSL/POTS Splitter. It may require a completely new wire pair dedicated for this purpose or it may be connected to a previously unused pair in an existing IW (inside wiring). It is important that it must not be connected to any jack on the premise other than the one used for the ADSL modem.

The actual task of installing the home run / splitter combo, in most cases, is a straightforward simple job if you are good with hand tools and have a basic idea of electricity.

The details of installing a home run are beyond the scope of a FAQ, but there are several links in the FAQ section to web sites that can provide the detailed instructions needed to complete the task of installing a home run.

Installing a home run in a residential home.
Installing a home run in an apartment or condominium
.

Andy Houtz DSL

by Andy Houtz See Profile edited by FAQFixer See Profile
last modified: 2007-10-15 09:25:02

IFITL (Integrated Fiber In The Loop)
IFITL (a.k.a. as PCData) is BellSouth's first broadband over fiber to the curb service and utilizes Marconi equipment that integrates voice, video, and data capabilities. It is not DSL but a 10Mb ethernet network from the ONU to your house. With IFITL no modem is used, but you must have a professional installation by a BST technician. They will install 10Base-T protector and a special EBN in the NID, run new CatX cable (or utilize existing spare pairs, if available) from NID to a RJ-45 wall plate, and then to the NIC card of your PC. Currently, IFITL customers are not eligible for Extreme 3.0 or Extreme 6.0, but IFITL can usually obtain slightly higher download speeds than FastAccess Ultra DSL customers because it uses traffic shaping instead of hard provisioning caps. Click here for additional IFTIL installation and connectivity information.

by FAQFixer See Profile
last modified: 2007-02-04 20:47:07

An INI (Indoor Network Interface) is an thick wall plate device that acts as a legal point of demarcation in a customer's apartment or condominium. Basically, it is where the phone company's phone/data wires end and the customer's home wiring starts. The phone company (and/or the property managers) are responsible for the wiring up to the INI and the customer (and/or the property manager) is responsible for any wiring after the INI. INIs are usually located in laundry closets, kitchens, bedrooms, or hall closets. Note: Not all apartments have an INI. A common INI is shown below.



Since an INI is where the phone company's wiring stops and the resident's wiring begins, it's a great place to isolate problems. For detailed instructions about testing your modem or circuit please reference the INI Test FAQ.

Andy Houtz DSL

by Andy Houtz See Profile edited by FAQFixer See Profile
last modified: 2006-12-21 23:47:07

"Interleaving" is an error correction protocol that is implemented on your line at the DSLAM and is used when your line is put on a "Noise Profile".

With Interleaving enabled, the DSLAM can correct errors in the data stream it receives before passing that data to your gateway router. It is usually implemented on noisy or marginal lines and can greatly increase sync stability and effectively eliminate "first hop" packet loss. The largest drawback to Interleaving is that it will increase your ping time, specifically to your first hop gateway router.

Noise profiles are provisioned automatically from the DSLAM without human intervention when line quality drops below certain perimeters. The BellSouth DSG can also manually add or remove customers from a Noise Profile.

Important note and helpful hint (despite what you think or want): You are on a noise profile for a reason! There is a physical issue between your modem and the DSLAM. Do not request to be manually removed from the noise profile unless the physical issue (on your side or BellSouths) has been resolved completely and your line stats are sufficient to handle the change. Otherwise you will have connectivity issue...which is the whole reason you were put on a noise profile to begin with. You can isolate where the physical issue is by pulling your modem stats from the NID. The other option is to have a field tech check the stats/wiring, but you may be charged if the issue is on your side of the NID.

Click here to see if your line is Interleaved.

Andy Houtz DSL

by FAQFixer See Profile
last modified: 2009-03-22 10:53:56

An IP (Internet Protocol) address is a unique identifier that differentiates every computer or device connected to the Internet from others. The format of an IP address is a 32-bit numeric address written as four 3 digit numbers separated by periods. Each number can be in the range 0 - 255 (e.g. 192.168.0.1).

Every computer or device that is directly connected to the Internet must have a different and unique IP address.

Feedback received on this FAQ entry:
  • Serveral problems accessing Pogo Free games. Most everything checks out after unblocking pop ups, clearing everything out, cache etc., everything, Java correct version and working, but now. I have two IP addresses given me on pogo, 159.153.235.1 and 159.153.235.2, one point, also finding and opening other ports that will work for me, using router with Verizon, Westel, Model# 327W, and firewall is blocking access to the game. Lots of information but I don't know how to use it. Can you help, or direct me to someone, someplace that can, I mean not another faq that I have to try and figure out what or how to proceed. June Muraco E-mail elixer11779@aol.com or juju24200002000@yahoo.com.

    2008-05-25 23:46:38



by leevis See Profile edited by KeysCapt See Profile
last modified: 2004-01-31 08:51:26

The BellSouth/BBR Line Monitor Section provides an easily accessible, reliable, independent indication of the actual performance of BellSouth DSL connections by comparing the line conditions of your fellow BellSouth Forum members.

Members sign up for basic line monitoring here at Broadband Reports. We then we use that information to generate graphs that show your line's stats along with others from your state. A very important factor is the way you setup the account. Even if you have a static IP, you must create the account as a dynamic IP. For security and privacy, BBR uses a cookie feature so that if you are logged in, only you can see your static IP graph. But for those that are not logged in, the graph is not visible, it will appear broken. So setting the graph to a dynamic IP will allow everyone to see the graph while the IP will remain hidden. If you have a static IP you do not need to run a DDNS client. Just set the monitor for "dynamic" and then type in your IP address in the "monitor this static address" box.

Each state has a separate section BellSouth/BBR Line Monitor Section. Click on the individual graphs to display more detailed information for that contributor's connection.


Click Here to Join


by jazzman916 See Profile edited by KeysCapt See Profile
last modified: 2004-01-31 07:54:37

A load coil is an inductor placed on the local loop by the phone company to improve voice quality. Load coils improve low frequency signals (voice) but supress high frequency signals (DSL). They are typically placed on the lines starting at 3000 feet in 6000 feet intervals and are designed to suppress the exact signal frequencies at which DSL operates.

Load coils improve low frequency signals (voice) but suppress high frequency signals (DSL). The effect, from the perspective of the DSL equipment, is the equivalent to adding 20,000 feet to the line length. There are supposedly newer load coils that are more DSL friendly but typically DSL does not operate properly through load coils, and they are a major source of loop disqualification.

by leevis See Profile edited by FAQFixer See Profile
last modified: 2008-03-05 10:38:56

The line coming from the Central Office (CO) and terminating at your premises.

by rjackson See Profile edited by FAQFixer See Profile
last modified: 2005-08-04 08:46:59

MAC is an acronym for Medium Access Control.

The MAC address is also known as the data link address. It is the address assigned to the NIC (e.g. ethernet network card). The address is a 12 digit hexadecimal number that is normally hard coded or "burned" into the physical board by the manufacturer. No two NIC's can share the same MAC address, so it is guaranteed to be globally unique.

by leevis See Profile edited by KeysCapt See Profile
last modified: 2004-01-31 08:53:12

Traditionally, a DSL customer's synch rate was provisioned directly on the DSLAM and hard set to a specific profile. A customer with a 768/128Kbps service would synch at 768/128Kbps between the DSLAM and the modem, regardless of the overall attainable line rate possible. MaxSync introduces two important differences.
1. The synch rate is no longer provisioned on the DSLAM. The DSLAM and modem will synch at the highest rate possible (within certain criteria).
2. Service speed is controlled via a RADIUS profile. So the customer mentioned above with 256/128 service may see a 8128/512 synch rate if they were changed to a MaxSync profile depending on their individual line conditions, but only get 768/128 throughput to the Internet.

The good news
Changes in service levels can be done without reprovisioning the DSLAM and accomplished with just a simple RADIUS change. It enables the possibility of offering bandwidth on demand service in the future. It also gives the customer and BellSouth the ability to see the overall condition/capability of the customer's loop. If a customers line can only MaxSync at 3552/384 they would not be a good candidate for the 6000/512 service. Conversely, a customer currently on 768/128 that MaxSyncs at 8128/512 shouldn't have any problems upgrading to 3000/384.

The bad news
Generally, higher bandwidth lowers the overall signal to noise margin and increases line attenuation. The MaxSync profile could create problems for a customer that were never an issue before. For example:

1472/256 service with traditional provisioning at the DSLAM
- Marginal line with attainable line rate of 3600/500
- Signal to noise margin of 10dB
- Line attenuation of 55dB
- Loop Capacity is about 41%
The customer has never had any problems even though the line is marginal because of the low synch rate.

Same 1472/256 service set to MaxSync profile
- Marginal line attainable line rate of 3600/500
- MaxSynch rate of 3552/384 (possibly with interleaving)
- Signal to noise margin of 6dB
- Line attenuation of 60dB
- Loop Capacity is almost 100%
The customer will probably experience constant connectivity issues and will be placed on an interleaved profile. Although newer interleaving techniques have reduced the overall latency as compared to older methods, it still introduces some latency.

How can I tell If I'm on MaxSync?
A simple way to tell if you are on MaxSync is to check your synch rate and modem stats. If your synch rate is far above your actual service plan, chances are you are on MaxSync. The highest sync rate is approximately 8128/512Kbps.

Important Information:
Due to differences in network topology, MaxSync is not available to all FastAccess customers. Additionally, just because you have been put on a MaxSync profile does not mean you are automatically eligible for all tiers of service!

Ultra-Mega, Don't Pass This Up Important Information:
Don't call the help desk and ask to have Interleaving removed. Fix the issue that is responsible for the problem that led to being put on interleave. You may be able to fix the problem yourself or it may take a truck roll. Regardless, fix the problem first!

Additional Information:
How do I check modem statistics? What do the numbers mean and are my stats good?
What is Interleaving and Fastpath?

Andy Houtz DSL

by FAQFixer See Profile
last modified: 2009-07-11 22:58:11

MTU (Maximum Transmission Unit)

MTU is the maximum packet size (in bytes) that can be transported reliably across any particular network, specifically an IP Ethernet network for this discussion.

The maximum size of an IP Ethernet packet is 1500, but several variables usually require a packet size that is less. For instance the largest MTU possible for PPPoE connectivity is 1492 because of an 8 byte PPPoE header. Other applications such as VPNs, SSH1, and L2TP may add additional overhead that would require a smaller MTU. It is very important to set the correct size. Too large an MTU will require fragmenting a single packet into two separate packets; too small loses transmission efficiency.

To find your optimum setting please reference this MTU FAQ.

Andy Houtz DSL

by Andy Houtz See Profile edited by FAQFixer See Profile
last modified: 2006-12-21 23:48:24

A NIC (Network Interface Card) is commonly used to refer to a network adapter. The most popular NICs are Ethernet cards that enable computers to be connected to an Ethernet LAN or similar network. NICs can be internal cards (PCI or ISA) or external devices like USB or PCMCIA cards.

Andy Houtz DSL

by Andy Houtz See Profile edited by FAQFixer See Profile
last modified: 2006-12-21 23:48:39

A NID (Network Interface Device) is a enclosure that acts as a legal point of demarcation at the customer's premise. Basically, it is where Phone Company's phone/data wires end and the customer's home wiring starts. The phone company is completely responsible for all wiring up to the NID and the customer is responsible for any wiring after the NID. NIDs are usually located on the side of house close to other utility entrance points. Note: Not all homes have a NID and some may only have a Station Protector at the entrance point. Some common examples are shown below as well as an open NID showing the customer access side with a single Entrance Bridge Network(EBN) module installed.





Since a NID is where the phone company's network stops and the home owner's network begins, it's a great place to isolate problems. The EBN (there may be more than one EBN depending on how many phone lines your house has) inside the NID will have a test jack where you can directly connect a phone or modem to the TelCo network and eliminate your inside wiring.



For more detailed instructions about testing your modem or circuit please reference the NID Test FAQ.

Andy Houtz DSL

by Andy Houtz See Profile edited by FAQFixer See Profile
last modified: 2009-02-20 08:58:44

"Noise Profile" is a term to identify a DSL loop whose data path is "Interleaved".

Interleaving is an error correction protocol that is implemented on your line at the DSLAM. With Interleaving enabled, the DSLAM can correct errors in the data stream it receives before passing that data to your gateway router. It is usually implemented on noisy or marginal lines and can greatly increase sync stability and effectively eliminate "first hop" packet loss. The largest drawback to Interleaving is that it will increase your ping time/latency, specifically to your first hop gateway router. There are various levels of interleaving depending on your specific line needs. The "deeper" (for lack of a better word) the interleaving, the more the latency increases.

Noise profiles are provisioned automatically from the DSLAM without human intervention when line quality drops below certain perimeters. The BellSouth DSG can also manually add or remove customers from a Noise Profile.

Important note and helpful hint (despite what you think or want): You are on a noise profile for a reason! There is a physical issue between your modem and the DSLAM. Do not request to be manually removed from the noise profile unless the physical issue (on your side or BellSouths) has been resolved completely and your line stats are sufficient to handle the change. Otherwise you will have connectivity issue...which is the whole reason you were put on a noise profile to begin with. You can isolate the physical issue by pulling your modem stats from the NID. The other option is to have a field tech check the stats/wiring, but you may be charged if the issue is on your side of the NID (Network Interface Device).

Click here to see if your line is Interleaved.

Andy Houtz DSL

by FAQFixer See Profile
last modified: 2009-05-01 14:21:36

Advertised DSL speeds are your "connection rate/data rate" not "download speed". Due to transport overhead it is not possible to download end-user data at actual advertised rates. Depending on the type of service and specific protocols used you will have about 12.5% (or more) of your bandwidth allocated for overhead. So a DSL customer with advertised speeds of 1472/256 will have a real world end-user data download speeds of roughly 1250/220 at best.

9.4% 5 byte overhead within 53 byte ATM cell
0.5% 8 byte PPPoE overhead
1.3% 20 byte IP overhead
1.3% 20 byte TCP overhead
12.5% Total Communication Overhead (minimum)

Important Note: Some speed test sites measure the advertised data rate while others measure real world file transfer rates. Sites that calculate actual end user file transfer rates take into account the transport overhead and will show a lower overall speed rate when compared to sites that measure data rates.

Andy Houtz DSL

by FAQFixer See Profile
last modified: 2009-02-19 08:47:13

PPPoE requires certain signals and information to establish, accept, control and terminate the session. The basic signalling is shown below.

A PADI (PPPoE Active Discovery Initiation) broadcast signal is sent by the host to the remote devices.

A PADO (PPPoE Active Discovery Offer) signal is sent by the remote device back to the host.

A PADR (PPPoE Active Discovery Request) unicast signal is sent by the host to the remote device.

A PADS (PPPoE Active Discovery Session-Confirmation) is sent by the remote device back to the host.

A PADT (PPPoE Active Discovery Terminate) signal is sent to terminate a PPPoE session. It is the proper way to terminate a session but is not the actual cause for the termination. The cause may be a simple timeout, a manual request by either end, or an out of spec line condition.

»docs.hp.com/en/5971-4750/ch01s03.html

by medic2797 See Profile edited by FAQFixer See Profile
last modified: 2005-04-24 11:16:55

POTS is an acronym for "Plain Old Telephone Service".

by FAQFixer See Profile

A Remote DSLAM is simply a DSALM that is placed in a Remote Terminal instead of a CO (Central Office). It enables customers that are not within 18K feet of a CO to qualify for copper based DSL. Usually the Remote Terminal is fed by fiber and then copper is used from there to the residence.

Siemens High Density Remote

Remote DSLAM White Paper

Remote DSLAMs are usually placed within Remote Terminals that resemble outdoor cabinets as shown below.


Picture courtesy of RadioDoc

Andy Houtz DSL

by Andy Houtz See Profile edited by FAQFixer See Profile
last modified: 2006-12-21 23:50:12

RWIN (TCP Receive Window) is the maximum amount of incoming data (in bytes) that a computer can receive and buffer before it is required to transmit an acknowledgement to the host sender.

Reliable TCP transfer uses acknowledgements from the receiver to the sender that it did indeed receive the data correctly. If sender has not received acknowledgement for the first packet it sent, it will stop and wait and if this wait exceeds a certain limit, it may even retransmit.

An RWIN that is too large will result in greater loss of data if a packet is lost or damaged. An RWIN that is too small will be very slow as more acknowledgements are required for the same amount of data.

To find your optimum RWIN please reference this Tweak FAQ.

Andy Houtz DSL

by Andy Houtz See Profile edited by FAQFixer See Profile
last modified: 2006-12-21 23:50:55

Certain network devices or equipment must use a reverse polarity cable (sometimes simply refered to as a "polarity cable") to function properly. A polarity cable swaps the polarity on the transmit and receive pairs. Important Note: A polarity cable is not the same as a cross over cable.





Andy Houtz DSL

by Andy Houtz See Profile edited by FAQFixer See Profile
last modified: 2006-12-21 23:51:17

A SLC96 (also known as Slick 96) is a Lucent Technologies "pair-gain" system that multiplexes 96 telephone lines onto eight pairs of twisted-pair wires. It is used extensively in the public telephone network to provide telephone service to areas that do not have enough twisted pairs to meet customer needs. The SLC96 actually uses four T1 circuits (24 lines per T1) to achieve the 96-line transport. The SLC96 is configured in a cabinet, one for inside rack-mount central-office use and the other (far end) as an outdoor cabinet. The circuit cards that are incorporated into the SLC96 design are separate and redundant power cards, battery back-up for the remote end, common equipment (control) cards, and a separate card for every two lines that are multiplexed (48-line cards for a full system).

by Andy Houtz See Profile
last modified: 2004-01-26 09:41:42

Remote Terminal is a generic term for equipment that is located in local neighborhood instead of the CO (Central Office). Placing equipment like like Remote DSLAMs, SLCs, and multiplexers remotely allows greater service expansion to customers in areas that normally are considered too far from the CO.

Remote DSLAM
SLC96


Picture courtesy of RadioDoc


Andy Houtz DSL

by FAQFixer See Profile
last modified: 2006-12-21 23:51:46

A splitter electronically isolates the lower frequencies of the telephone signal from the higher frequencies of the DSL signals. Splitters are the main device used when running a homerun (dedicated wiring for the DSL signal) because they also physically isolate the DSL and POTS wiring. Splitters are more robust than the standard in-line microfilters supplied in the self install kits and eliminate the need to have filters on every phone.

Four main types are available:
External Splitters - Encased in separate, weather-proof enclosures for stand alone installation.
Internal NID Splitters - Designed to fit completely inside a residential NID (Network Interface Device).
Home Security Alarm Splitters - Designed to work with RJ-31X alarm system connections. More information is available here.
INI Splitters - Designed for apartments/condominiums that use an INI instead of a NID. More information is available here.

Note: The appearance of these links in no way constitutes any endorsement and they are provided as a convenience only. No representation is made as to the suitability of these or any other commercial links included here.

eBay is a great source for new splitters at very good prices. Also, several retailers sell to the general public. Please check the following links:

Hometech Solutions
TXINET
Santa Cruz Electronics
HippoVariety
ADSLProducts
TII Authorized Vendors


Siecor/Corning External Splitter


Bourns Internal Splitter


TII Internal Splitter


Keptel Internal Splitter


Siecor Dual Line Internal Splitter


Wilcom Splitter


Excelsus RJ-31X Security Alarm Splitter


Siecor INI Splitter (Wallplate)


Siecor INI Splitter (Wall Mount)


Andy Houtz DSL

by Andy Houtz See Profile edited by FAQFixer See Profile
last modified: 2006-12-21 23:52:17

There are specialized DSL/POTS splitters designed for apartment/condominium applications. For maximum effect, the splitter should be connected directly after the INI (Inside Network Interface), if available. If your apartment does not have an INI then try to find the "first jack". The first jack is, as the name implies, the first wired jack into your apartment from the telco network. Replacing the first jack with a splitter will isolate the rest of the inside wiring and allow you to create a homerun. Detailed instructions on installing a homerun within an apartment are available here. Two common DSL/POTS splitters designed for apartment applications are shown below.

Ebay is a great source for new splitters at very good prices. Also, several retailers sell to the general public. Please check the following links:

Note: The appearance of these links in no way constitutes any endorsement and they are provided as a convenience only. No representation is made as to the suitability of these or any other commercial links included here.

Hometech Solutions
Santa Cruz Electronics
HippoVariety


Siecor INI Wallplate Splitter


Siecor INI Wallmount Splitter

Andy Houtz DSL

by Andy Houtz See Profile edited by FAQFixer See Profile
last modified: 2006-12-21 23:52:34

Older homes may only have a simple Station Protector instead of a NID (Network Interface Device). If you only have a Station Protector you must call 611 (Service and Repair) and select telephone repair option (not DSL) and request a proper NID. Do not call BellSouth Internet Services. Station Protectors are not automatically replaced if you get DSL service so customers must request a NID replacement. There is no charge to the customer for the new NID installation and it will be completed by a BellSouth technician. Do not touch or attempt any wiring changes on the station protector. Several common Station Protectors are shown below.


Andy Houtz DSL

by Andy Houtz See Profile edited by FAQFixer See Profile
last modified: 2007-08-24 06:54:06

TNI (Telephone Network Interface) is a alternative term for a NID (Network Interface Device).

Andy Houtz DSL

by Andy Houtz See Profile edited by FAQFixer See Profile
last modified: 2006-12-21 23:53:12

A VRAD (Video Ready Access Device) is the local FTTN equipment for AT&Ts voice/video/data services marketed as U-Verse. Two common deployment configurations are used.

Click for full size

Pad Mounted VRAD
Picture courtesy sempergoofy


Click for full size

Pole Mounted VRAD


by FAQFixer See Profile
last modified: 2008-10-21 11:20:11

WAP is an acronym for Wireless Access Point. WAPs are used to bridge a standard wired network to a wireless network. WAPs are not the same as Wireless Routers because WAPs do not provide NAT or DHCP capabilities and must be used in conjunction with a standard router if more than one computer is to be networked.

For information about configuring a WAP with a Westell modem please click here.
Andy Houtz DSL

by Andy Houtz See Profile edited by FAQFixer See Profile
last modified: 2006-12-21 23:53:28