The 100Mbps Fibre Distributed Data Interchange is only beginning to challenge 10Mbps Ethernet in the market, but already users say it’s too small and new approaches are putting it under threat, says Chris Rose
It finally happened: Network Equipment Technologies Inc’s Adaptive Corp subsidiary announced details of its first Asynchronous Transfer Mode switch specifically designed for local area networking (CI No 1,962). Apart from the speed of the technology, which provides each device with exclusive rights to a 100Mbps channel, Adaptive’s ATMX switch poses questions as to the long term viability of shared-medium local area networks such as Ethernet, Token Ring and Fibre Distributed Data Interface, where devices queue up to put data onto the network. A quick look around the networking world suggests that a shift in thinking is under way – away from shared medium and towards centralised switching.
Shared medium gone
For example, take 3Com Corp’s private Ethernet, where each networked device has its own Ethernet segment attached to a hub. It’s a switching system in all but name. So what if the hub is acting as a bridge – the idea of the shared medium between communicating stations has gone. Similarly, Digital Equipment Corp’s proposed Gigaswitch uses the same trick to squeeze the last drops of capacity from FDDI. Both DEC and 3Com, and now Redwood, California-based Adaptive, agree that existing users are pushing the speed barriers imposed by their existing networks. Likewise, both 3Com and Adaptive agree that the private segment approach brings with it benefits other than speed, especially in terms of manageability. While it will be this combination of speed and manageability that will contribute to any success that Asynchronous Transfer Mode has in the office, Adaptive reckons that it is the latter that will knock shared media networks out of the ring eventually. It is the high-end workstation vendors that are currently taking an interest. Sun Microsystems Inc has committed to placing an Asynchronous Transfer Mode interface on the motherboard around 1994, and Adaptive’s chief executive, Audrey MacLean, claims that Sun, previously interested in FDDI as a standard feature, is now switching its attention to Asynchronous Transfer Mode. Moreover, she asserts that by 1994, Asynchronous Transfer Mode adaptors will be incorporated into everyday personal computers. FDDI, she says, is dead. It has no future and can only be considered an an interim measure. No more than you would expect from a company that has been plotting its Asynchronous Transfer Mode strategy since 1988, although its arguments are fairly persuasive: people buy FDDI because it is the fastest local medium available. Workstation users are already chafing at its limitations and multimedia applications running under Windows are more than capable of eating 20Mbps of bandwidth. Meanwhile on the technology front, Asynchronous Transfer Mode adaptors are technologically no more difficult to build than FDDI. Current high prices are ascribed to novelty rather than difficulty, and with 120 companies now involved in the Asynchronous Transfer Mode Forum it can only be a matter of time before the technology veers towards the commonplace. But what about the switch, that big chunk of technology that FDDI does not require and which starts at $45,000 for a minimal configuration? The company points to the number of users that are building hub-based FDDI networks anyway and slyly refers to the growing number of FDDI vendors that are talking about using Asynchronous Transfer Mode technology inside their FDDI hubs. It is a hub-based system that Adaptive has in mind when it claims that users bridging more than three FDDI networks would be financially better off with Asynchronous Transfer Mode. Adaptive is going to have a fight on its hands if it is to compete with Basildon, Essex-based Netcomm Ltd, however.
Plumped
As reported earlier this year, the company is readying its own Asynchronous Transfer Mode-based switch, dubbed DV2, for general release in December (CI No 1,902). The fir
st beta test sites should be receiving their switches in October. The company is claiming switching speeds of 3.2Gbps – twice that of Adaptive’s ATMX switch, and the company has plumped for a cross-switch architecture rather than the shared bus approach taken by its American rival. In addition, the Netcomm switch looks as if it should be cheaper, and possibly more flexible than Adaptive’s. The Netcomm 16-slot chassis will cost around UKP15,000 with the 100Mbps local fibre link ports costing around another UKP4,000 apiece. The nice thing about Netcomm’s product is that it has a standard controller board, and a daughter board is added to define its personality. The switch is not limited to Asynchronous Transfer Mode connections and can support Ethernet, and FDDI connections, among others. Despite the support for FDDI in Netcomm’s product, managing director Richard Barnett agrees with Adaptive that the technology is in for a tough ride. No doubt FDDI companies will vigorously argue the point, but at least some major FDDI customers will be given serious pause for thought.
