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Note: This section is out of date and no longer maintained.
It is retained for the value of any residual information contained in it.

DSL - Section 1

This is the start of our information pages all about DSL. Below the line, you can find links to all the sections we offer. In the text, you will also be able to click on links (blue words).

The page is divided into two, clicking a link in the top half, fills in the answer at the bottom.

So what about DSL? well .. if you have no time, at least read our 10 key points about DSL in the US.
You might also want to look at pictures to see how DSL reaches your home, and connects to your PC.
Or you can start with a basic introduction now... or to continue, with the tell me more link.

tell me more...


A picture tells a thousand words they say, so this section attempts to describe some DSL installations using pictures.

This first one shows you how your home is hooked up to the internet via DSL.
CO stands for central office. There are over 30000 central offices in the US, each responsible for phone service (and now potentially, DSL service) for a small region indicated here by the green area. These regions are not as you might expect, circles drawn around a CO office on a map, but follow property street or county boundaries, so tend to be quite straight-sided.

The blue cloud is network interconnecting many different locations (such multi-connected networks are always represented as clouds in network diagrams), this cloud may be entirely Telco owned or run, or could be owned by a CLEC, or a combination of both. It is not, however, the Internet.

The internet starts at the ISP, and beyond the ISP, its internet provider.

This next diagram is of a basic ADSL (a common form of residential DSL) in a home. The splitter depicted here is a small box that strips off the phone signal from the line from the Telco, and leaves the data (indicated by the red shaded lines), to be routed to the data equipment, on RJ11 (phone) inside wires. Note that the RJ11 plate depicted in this diagram is upside-down.. this still works, but since dust accumulates on the socket blades, they will fail after a while. Please ensure all sockets in your house are the other way round (prongs hanging down).

A DSL setup, with a filter instead of a splitter, allows the data and telco voice signal to flow through the house phone wires, but filters it from the telephone or fax machines.

Sections available: 56k modems, ADSL, ATM, ATU-C, ATU-C/R, ATU-R, AWG:, bandwidth, Bell Operating Companies, BERT, BRI, BRIDGE TAP, bridge taps, bridged ips, cable modems, CAP, CBR, CCITT, CIR, CLEC, CLLI, CO, CODEC, Comparing DSL to 56k modems, CPE, CSU, DAML, DCE, DCLEC, DHCP, distance, DLC, DMT, DMZ, DNS services, dsl, DSL, DSL-1, DSL-2, DSL-3, DSL-4, DSL-5, DSL-6, DSL-7, DSL-8, DSL:2, DSLAM, dslam, DSU, DTE, ECHO CANCELLER, extra IPs, family of standards, FDM, filter, firewall, fixed ip, FTTC, FTTH, G.lite, HDSL, HFC, high speed, hub, ICMP, IDSL, idsl, IEC, ILEC, inside wiring, installation, introduction, ISDN, ISP, ITU, IXC, key points, LATA, latency, LEC, lit up, load coil, local loop, loop, maximum DSL speeds, Mbps, MDF, MODULATION, MVL, NAT, NEBS, NEXT, NID, OC48, operating servers, ordering process, packet drops, PCM, pictures, Point of Demarcation, POTS, PPP, PPP vs bridged, PPPoA, pppoe, PPPoE, PRI, private ip, PSTN, PTT, PVC, QAM, RADSL, RBOC, registry settings, router, satellite, SDSL, security, sharing, shielded, SLA, SNR, socks, splitter, SVC, TDM, technical hurdles, terms and conditions, throughput, truck roll, twisted pair, UBR, UDP, UTP, VBR, VDSL, wireless,