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Asymmetric Digital Subscriber Line (ADSL) is new technology allowing users to access data at much higher speeds than with 56k phone modems. Internet speeds are available for 256k/512k/1500k/sec. ADSL uses the existing copper telephone lines and end users can have a phone conversation at the same time as downloading.

How it works technically

ADSL is the acronym for Asymmetric Digital Subscriber Line.

It uses the frequency spectrum between 0kHz and 4kHz for your telephone service and 20kHz to 2.2MHz for data transfer over a normal unconditioned copper telephone line, without affecting the operation of the telephone in any way.

This line provides asymmetric transmission of data, with up to 1.5Mbit/s downstream (to the user) and up to 256Kbit/s upstream, depending upon the line length and line/loop condition. This is many times faster than existing phone modems (56k/sec) and ISDN (64-128 k/sec) services.

ADSL depends upon advanced digital signal processing and creative algorithms to squeeze the information through the normal telephone twisted-pair lines.

The ADSL service into a home or business will be transmitted on the existing Telstra copper cable network as is shown below.

In the home, the equipment set up will be as shown below.

As shown, your telephone call and your data transmission are separated by a filter thus allowing dual usage of the line.

End User Connection

The end user can connect in a number of different ways depending on the configuration.

Single PC

A single PC can connect via an external modem using either an Ethernet (10BaseT) interface or a Universal Serial Bus (USB) port, or an internal modem.

Modems using an Ethernet interface will use PPP over Ethernet (PPPoE) protocol between the modem and the Access Concentration Network, and will require Client Software to be installed on the PC to allow the Dial Up Networking (DUN) session to interface with the Ethernet port. PPPoE allows for multiple concurrent sessions to be established with different networks (eg corporate network plus an ISP).

USB and Internal modems will use PPP over ATM (PPPoA), and will use device drivers rather than client software. USB modems will only allow a single concurrent session.

Installation

We can provide installation as a chargeable option.

The modems in most cases simply plug into a spare telephone socket. Line filters are required in series with each telephone to attenuate high frequency noise and ring trip spikes. These filters will be supplied with modems and are suitable for self-installation.

When there are more than 3 parallel telephones (or a Small Business System or PABX), a Centralised Splitter must be installed after the network Boundary Point. This splitter must be installed by a licensed cabling contractor. However, because it separates the data and voice components into separate circuits, there is no need for Line Filters.
Client software and filters will be supplied with the modem.

Connecting to Networks

Connection of a network is more complex and in some cases will require a router. The most common interface will be Ethernet, since most networks are 10BaseT. There are a number of network configurations supported.

Any modem or router which is certified for use on the our network can be used, including the Alcatel SpeedTouch Home and USB modems and SpeedTouch Pro Router available for purchase from us.

Incompatible Products

The following products and services are not compatible HyperConnect

• EasyCall Multiple Number
• Duet®- Phone and Fax Multiple Number
• Spectrum Services
• Indial Services
• Private Lines
• Private metering (both 50Hz and 12kHz)

PPP Authentication Security

For PPPoE and PPPoA, the end user name and password is validated by the RADIUS Proxy to ensure that the user is allowed access to the corporate network. The network validates the username and password with the customer RADIUS server, which can be owned and operated by the customer or hosted by us. A separate Authentication PVC is required to connect the RADIUS Proxy and the customer RADIUS server to validate usernames and passwords. There is no charge for this PVC.

Static Routing Security

When Static Routing is used there is no username and password validation, however all valid user locations are specified in the TAS routing tables. Customers can provide higher layer security through the use of tokens or smartcards.

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