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Course: ADSL installation & troubleshooting at TFN
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Next available session:

Avail.:next session probably Feb/2013
Admits:volunteers only
Prereq.:technical aptitude & experience
Cost:vol $0, supplies included
Where:TFN office
When:typically Sunday mornings 11 am - 1:30 pm
Length:4 class meetings, 2.5 hours each, starts on demand

Format:lecture with class participation; brief supervised lab
Homework:none assigned
Extra help:by phone or email


  • user-level experience with ADSL.
  • user-level experience with the Internet.
  • aptitude with computer technologies.
  • aptitude with tools — screwdrivers, pliers, wire cutters.
  • basic understanding of electricity.
  • ability to quickly pick up jargon and new ideas.


Iain Calder manages TFN's ADSL infrastructure.  He has been troubleshooting ADSL connections for TFN members and teaching the subject to TFN staff for a few years.


This is not a thorough course.  We cover only the surface of each topic, understanding only its gist.  This suffices for troubleshooting, and is a good starting point for more specialized studies.

This is a fast-paced course.  It assumes no prior knowledge of networking, data communications, or telephone cabling but it requires a certain kind of smarts: you must be able to assimilate new technical concepts quickly.

This is a stimulating course if you are interested in high speed communications technology.  In a very short amount of time, you get a bird's eye view of how all the pieces fit together.

Every minute of lecture builds on what came before.  If you miss even fifteen minutes of class, you will find it very difficult to follow the rest of the course.  We work with your schedule, to ensure that everyone can attend all classes.  If someone needs to visit the washroom, the class takes a break.  If someone must leave early, we adjourn early.

The lecturer stops frequently to take questions.  Students participate in exercises to help everyone grasp a concept before moving forward to the next topic.

We discuss how ADSL works under the hood, in practical, physical terms, skipping most of the theory.

We see different types of cabling and discuss their differences.  We look at the insides of telephone sockets and learn the different colour codes used for telephone wiring.  We learn some of the jargon used by Bell's line technicians and the ways in which our work interacts with theirs.  We learn shortcuts and tricks of the trade for testing.

We learn about data packets and how they are routed, using a simplified view of the world.  We explore the concept of protocol stacks.  We look at the parts of TFN's network that are involved in our ADSL service, and explore how and where things can go wrong, all along the length of a connection.

Finally, we configure an ADSL modem.


Upon completing this course, you will be able to:

  • disassemble a telephone socket, divert a connection inside a home's telephone cabling.
  • trace a telephone line to find its other end.
  • test a non-working ADSL connection of a TFN subscriber.
  • recognize the symptoms of different types of connection problems.
  • visualize TFN's network and the possible causes and locations of a problem.
  • accurately diagnose the cause of the problem.
  • correct problems that are within a TFN subscriber's premises.
  • communicate about a problem, succinctly and accurately, with other technicians at TFN or with others in Ontario's ISP industry.


None assigned but self-directed reading, on the web, is encouraged.

Supplies & equipment:

  • It is very useful to have an ADSL connection at home with which to experiment, assuming you can afford to break that connection.  However, the course relies only on TFN equipment.


  • essentials of POTS telephone and frequencies used.
  • ADSL frequencies and buckets.
  • ADSL synchronization concepts.
  • PPPoE authentication, RADIUS servers.
  • cable types — twisted pair, coax, parallel.
  • telephone cable colour codes.
  • telephone socket & demarcation types
  • IP concepts — packets, essential features of packet formats.
  • network layers — ethernet, ATM, IP, PPP.
  • IP static routing concepts — each router decides the next hop.
  • TFN network topology.
  • failure points, scenarios, and frequency of occurence.
  • diagnostic tools and methodology.
  • modem configuration.

About ADSL:

ADSL (Asymmetric Digital Subscriber Line) is a technology for transmitting data at high speed over telephone wires.  Like any technology, it has advantages and limitations.  For example, it doesn't work over long distances.

At TFN, we use ADSL extensively, to provide high speed connections to our members.  Our use of ADSL depends on infrastructure owned by Bell Canada that is regulated by the CRTC (Canadian Radio-television and Telecommunications Commission).  This dictates particular network topologies, which also have their advantages and limitations.

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