Sixteen Bits Online


TIP - The Internet Project

by Iain Gould

I'm back. After not being able to submit a report last month (read: I forgot), I thought that maybe everyone out there in PCUG-land might be interested to know what is happening with TIP.

On the first of October, 527 TIP accounts were suspended for not signing the Acceptable Use Policy declaration. Since then, approximately 50 have been unsuspended. If you are still suspended, and wish to be reinstated, then rock on down to the PCUG Centre at Northpoint Plaza any weekend (except long ones) between 9am and 5pm or Monday, Wednesday, Friday between 10 am and 2pm and sign a Declaration. Your account should be reinstated within the week.

On the other hand, if you have decided to let your TIP account lapse for any reason, we would really appreciate it if you could let us know so that we can clean up some old accounts. Important News!

By the time you read this, TIP will have relocated (with any luck) to the new centre at Northpoint Plaza - it will be in the room down the back (no, not in the toilet). Thus everyone will need to reconfigure their dialler software to connect to the new number for TIP. By the way, the number is now:

206 6200

How To Update Software

Here are the instructions for Trumpet Winsock (Windows 3.x) and for Dial-Up Networking (Windows 95). Those of you using Macintosh, OS/2, Linux, CP/M or MVS/XA will have to work it out.

Trumpet Winsock

Windows 95 DUN

Why doesn't this number follow the pattern of the other PCUG numbers at Belconnen?

As part of the relocation, the PCUG invested in upgraded routing and access hardware - a Cisco AS5200 Universal Access Server. This device provides basic routing functionality between the Public and Private networks of TIP, as well as dial-in services for TIP users using ISDN technology (see diagram).

The AS5200 provides up to 60 in-bound lines, initially 48 due to hardware delivery issues. Instead of 60 standard Telstra phones lines being required (as is the case with the equipment used up until now), only two Primary Rate Interfaces (Macrolinks) are used. The modems will initially be V.34 digital modems.

The benefits that we will achieve from this hardware upgrade include:

  1. Increased number of dial-in lines.
  2. Digital connectivity (better quality at the TIP end).
  3. Elimination of multiple external modems that require individual configuration and management.
  4. Better management by the use of fully integrated access equipment.

What Is ISDN?

(Courtesy of Telstra Learning)
"ISDN stands for Integrated Services Digital Network. The concept of an ISDN type of service has been discussed by the business and scientific communities for many years. As long ago as the early 1970's, discussions were taking place about the need for a high speed digital switched service capable of carrying voice, data and image in an integrated way. It took until the late 1980's for these discussions to result into a practical reality. Telecom Australia [now Telstra] was amongst the first telecommunications companies in the world to offer ISDN to its customers, and is leading the world in the provision of a national ISDN service. Telecom introduced ISDN in mid 1989, providing a totally digital and flexible network offering direct access to a wide range of communications services. The network operates at a basic speed of 64 kbit/s enabling users to transmit voice and high speed data on a simple circuit-switched connection."

Whew. That's the official line, but what does it mean? ISDN can be thought of as a fully digital version of the original, traditional, pervasive public telephone network (PSTN). Both are circuit-switched networks (i.e. calls are made, and a circuit established through the carrier's network and maintained for the duration of the call). Both use the same numbering scheme - and this means that normal telephone (and fax or modem) calls can be made from one network to the other.

However, ISDN is delivered on a multiplexed connection - either 2 B Channels (64 kbit/s 'user' channels) or 30 B channels. The former is termed a Basic Rate Interface and called Microlink by Telstra, and the latter is termed a Primary Rate Interface and called a Macrolink by Telstra. In the U.S. a PRI only has 48 B channels. The 64 kbit/s chunks are derived from the basic building block of all public telecommunications networks - a single digitised voice circuit.

Compare the following: A Microlink can be installed in your home on two pairs of standard telephone cable (four copper wires - standard for most homes) and will provide up to 128 kbit/s of data transmission, OR a single telephone call at the same time as 64 kbit/s of data (with the right equipment). A normal telephone line uses only one pair of wires but can only provide EITHER a single telephone call OR a data connection of up to 38.4 kbit/s real data transmission. This is one of the benefits of a digital network. The main reason that ISDN is not more widespread throughout the consumer market is Telstra's pricing regime :-( Business and Government have been big users of ISDN in this country.

I could go on. Maybe another time.

What are 'Digital' modems?

Aren't all modems digital? Well yes and no. Modems are devices that MODulate digital data from (for example) your PC onto an analog carrier wave for transmission across the standard PSTN network, and then DEModulate it back to digital data at the far end.

But didn't I say that there will be no analog connection to TIP with the AS5200? (Note here: AUUG dial-ins to TIP will remain on the previous modem technology and equipment) A fully digital modem still modulates and demodulates data but using a digitally-coded carrier.

Public telecommunications networks use a technique called Pulse Code Modulation (PCM) that converts a standard voice analog waveform into a 64 kbit/s digital stream. As this is a global 'standard', it is possible to act on this digital stream as if it were a true analog signal. Thus the digital modems do their work (and can detect) an analog wave coded into the digital ISDN channel.

What About Bandwidth?

'Bandwidth' here refers to our link up-stream to the rest of the Internet. Our service provider is currently Access One, and our bandwidth (or link speed) is 128 kbit/s using the 2 B channels on an ISDN Microlink. We are taking advantage of a widely-used, Australian-only feature of ISDN - Semi Permanent Circuits (SPCs). This is where we pay a flat rate to Telstra to have our ISDN calls held up permanently. Initially, we are not changing the arrangements for this bandwidth (other than relocating our end) - that is we are still running at 128 kbit/s. The Internet Project Management Committee, in conjunction with the Committees of the PCUG and AUUG, are investigating options for increasing this to (probably) 256 kbit/s in the near future. There are 3 components to this decision:
  1. The cost that Access One will charge us to connect at 256 kbit/s to their network;
  2. The cost that Telstra (or someone else) will charge us to transport our traffic to Access One at 256 kbit/s;
  3. The actual connection equipment and service (which probably won't be ISDN in this case).
Needless to say, the costs involved are pretty scary! Stay tuned to this channel for further information about this.

If you have any more questions on any of the above, feel free to email me. Catch ya next time.

Iain Gould is one of the many volunteers that keep TIP ticking. He can be contacted by e-mail -

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