Corporate to Corporate Delivery Systems

2.1 Leased lines

Telstra and Optus offer many products suitable for the delivery of multimedia content. They all use digital networks within the telephone exchange network and range from the relatively slow Digital Data Service (DDS has data rates from 2.4Kbit/s to 48Kbit/s), through alternative products with names like DDS Fastway (64Kbit/s to 1984Kbit/s in 64Kbit/s increments), Broadlink 2M and Megalink 2Mbit/s.

Leased lines can be obtained from the telecommunications companies which are of higher speeds, usually in multiples of 2Mbit/s eg: Optus Broadlink 4x2M.

The cost structures for the faster products are based on an installation fee (from $3500 to $70000) and annual rental based on distance. The ongoing costs greatly exceed installation costs ranging from$15000 for short range leased lines to $50000 for 40km.

All of these products offer a fixed bandwidth for which the customer pays.

2.2 Point to point radio

Spread Spectrum Radio (SSR) is becoming a popular and cheap way to link LANs between nearby buildings. Typical products support speeds of 1-2Mbit/s over a distance of up to 3km. There is an Ethernet standard for SSR ethernet links, but most products are proprietary systems - which are transparent to the ethernet networks that they link.

Microwave links are proprietary systems mainly used to interconnect two networks, with distances ranging from 1km to 100+km (which may require retransmission towers along the way). Microwave link speeds commonly available are systems of 2Mbit/s, 8.448Mbit/s and 34.368Mbit/s and up to 155Mbit/s. A 34Mbit/s link costs roughly $50,000 for the Microwave hardware, and there are additional costs for network adapters (routers, terminal adapters), as well as annual license fees.

The Microwave links can carry almost any sort of traffic - Ethernet, ISDN, even ATM as long as the interface hardware is available.

Telstra is now also offering Satellite based links (Iterra) which will provide the equivalent of the basic rate ISDN service to remote users.

2.3 ISDN Primary Rate

Primary Rate ISDN is supplied as 30B+1D channels which represents 30x64Kbit/s digital channels with some control signalling. This gives a useable data rate of about 2.048Mbit/s. To use the combined bandwidth of the ISDN channels requires hardware that aggregates the signals at each end of the ISDN link.

Generally Primary Rate ISDN (sold as Macrolinks or Megalinks) are used by customers with large PABXs to provide a cost effective method of connecting many exchange line services (eg. Indial) via a single access point. The hardware to aggregate data channels is expensive and rarely combined more than 6 or 7 channels (384Kbit/s)

This is one form of the leased lines mentioned above - a Megalink 2M.

2.4 Austpac EFTPOS

The Austpac network is a packet switched data network, suitable for small amounts of data to be sent long distances to a large number of locations.

Austpac support both synchronous and asynchronous terminals at the AUSTPAC® exchange, with dedicated access (X.25) for synchronous transmission at speeds up to 128kbit/s. Dial in access (X.28) for asynchronous transmission at speeds up to 14.4kbit/s (with 19.2kbit/s optionally available using compression).

An extension to the AUSTPAC network is Transend(TM) which is a national packet switched network for the transmission of aggregated volume synchronous data at speeds of 1200 or 2400bit/s. It is mainly used to support EFTPOS but has other high uses such as booking agencies, which use many connections coming back to a single point. It is a secure national network conforming to international standards.

This technology is too slow and expensive to be seen as a major on-line multimedia delivery system.

2.5 Frame Relay

Frame Relay is an enhancement to the ISDN network, which provides for variable bandwidth services of 64Kbit/s up to 2Mbit/s with the ability to support short term bursts of data at higher rates when bandwidth is available.

Frame Relay has guaranteed speeds and fixed monthly costs based on the required normal bandwidth.

The Frame Relay network extends internationally using the generic X.36 international standard, it also can connect into Telstra's internet offerings as well as other networks like X.25 and the international IP Internet network.

This would be a more suitable network connection than a primary rate ISDN line for multimedia delivery system when large amounts of data are expected to be delivered, as the cost is based on your required nominal bandwidth. Additional bandwidth that is used when capacity is available is free. 2.6 ATM

Asynchronous Transfer Mode - ATM is believed to be the way of the future within the telecommunications industry. ATM is the foundation of the new worldwide Broadband ISDN and is a major new transmission technology which supports very fast transmission rates.

ATM Standards are developed by the ATM Forum.
ATM is a packet switched network that breaks all traffic into very small parcels for transmission through the ATM network.
ATM offers a guaranteed quality of service (bandwidth, transmission delays, error rates) and is reliable with a scalable bandwidth (from 34Mbit/s to 155Mbit/s with possible future enhancements up to 622Mbit/s and beyond).
ATM products are available from many vendors with both Optus and Telstra offering an ATM backbone service (not necessarily available to retail customers as yet).
ATM hardware is relatively expensive and it would be safe to assume that the cost to use this service will be quite high initially. It is possible to use ATM over Microwave links, and this may be a viable multimedia delivery system between a corporations sites.
Telstra's Frame Relay service is seen as a migratory step to ATM.

As a Multimedia Delivery System, the ATM network would be ideal, with it's very high bandwidths, but at present the Telstra and OPTUS ATM networks are still fairly experimental.