From public telephony to public Ethernet?
Since the invention of the telephone 130 years ago, a series of public networks have been built around key inventions in telecoms. First there were wireline telephone networks; then wireless broadcast radio; broadcast television; and mobile telephony in its analogue (1G), digital (2G) and now mobile multimedia (3G) forms. These networks are all public in that they have been built intentionally to reach practically everyone. They have been delivered by both public and private means, driven by both direct commercial imperatives as well as political vision in terms of their impact on growth and prosperity in society in general. Is it now time to consider Ethernet as the next underpinning technology for achieving the same level of public access to the Internet?
Of course, Ethernet is only the technology: it is the Internet applications in which we are really interested. What's more, the other networks can also carry IP and Internet traffic: we are already building 3G networks for the mobile Internet. Nonetheless, for high-bandwidth residential access, video-oriented services, wireless LANs and enterprises, Ethernet (whether wireline or wireless) is emerging as the technology of choice for a range of future services. For Ethernet to adopt such an all-encompassing role, it cannot remain as a business-oriented and LAN-focused best-effort technology. It must evolve — as it is already doing. For example, standards for Ethernet in the First Mile are being developed by the Ethernet in the First Mile Alliance (EFMA), of which Ericsson is a founding member, and will be ready in 2003.
For Ethernet to become the basis of something akin to the public telephone network, its mass-market features must be further enhanced. Firstly, more focus must be put on achieving the lowest-possible cost in the customer-facing network since, if costs are too high, consumers and operators will be reluctant to invest in Ethernet. And simultaneously, quality, maintenance and reliability expectations must be met or exceeded. Secondly, the high bandwidths that can be aggregated from new broadband services must be accommodated with new capacity — particularly in metro networks — since, if enough capacity is provided to aggregate high-bandwidth services, broadband will experience a "brown-out", just like dial-up Internet before the telecom bubble.
In access networks, DSL is the most common broadband method so it must accommodate Ethernet and vice versa. It will be impossible to meet either the low-cost or the high-capacity requirements competitively by simply expanding classic ATM-over-SDH. Ethernet must be used to its full potential, and DSL access multiplexers (DSLAMs) will increasingly embrace Ethernet and enable smooth migration to deployment of Ethernet in the First Mile. For example, an Ethernet DSL access solution is now available from Ericsson that includes an ultra-compact IP DSLAM able to serve as few as eight DSL subscribers, and scale in 8–10 subscriber steps cost effectively.
In the metro network, there are several alternative ways to eliminate capacity bottlenecks from broadband access. Existing ATM-over-SDH networks can be migrated, so current ATM-based DSL systems can be aggregated using next-gen SDH, which offers efficient and dynamic transport of data over existing SDH networks. Next-gen SDH will also be of interest for either very large or very small or remote service areas where an operator needs a presence with the same quality as in denser areas but where the installation is too small to warrant a whole new network build.
For Ethernet broadband access-networks, however, especially to residential, SOHO and SME subscribers, Ethernet transport networks are more cost-effective. In this context, it will be important for Ethernet to offer the quality and reliability that business and home users have come to expect from the classic telephony network. This is one of the drivers behind the development of new Ethernet standards and new ways of interworking between Ethernet and other transport technologies.
In the future the expanding reach of fibre in metro areas will push optical Ethernet all the way to the home and enterprise. Commercial fibre-to-the-home is already available and, with new techniques such as air-blown fibre, can be applied cost-effectively to new installations and network refurbishments.
Per O Andersson
Business Development Director, Ericsson