Menlo Park, California-based Cisco Systems Inc and Bedford, Massachusetts-based Wellfleet Communications Inc chose the same day at the same show to launch three-phase Asynchronous Transfer Mode strategies. Both companies have a similar plan whereby an external Asynchronous Transfer interface is initially grafted onto their existing products, before being internalised. Of the two, Cisco Systems has issued the more detailed proposals. Indeed Cisco’s first phase is already complete and doesn’t involve Asynchronous Transfer Mode at all. Instead, it sees the first stage as encompassing the work it carried out with ADC/Kentronix to build a Data Service Unit front end. This front end, which the company says has been demonstrated running at 45Mbps, segments the data into variable length SMDS packets rather than fixed length Asynchronous Transfer cells. Still, by early next year the company says that this will be replaced by a true Asynchronous Transfer Mode Service Unit linked to the router via a high speed serial interface, ushering in Cisco’s second phase. Also included is the ability to support both connectionless- and connection-orientated traffic. Cisco’s third phase will be ushered in by early 1994, as the Data Service Unit approach is abandoned in favour of a direct Asynchronous Transfer interface. Asynchronous Transfer Mode will be treated by the Cisco router as one of many supported media says a company statement which explains that the router will internally construct and deconstruct Asynchronous Transfer cells at up to 155Mbps. In effect it will become a small Asynchronous Transfer switch. Such is Wellfleet’s eventual aim too. While Cisco is boasting that it has a device running at 45Mbps (DS-3 speeds) even if it isn’t true Asynchronous Transfer, Wellfleet’s phase one available to all customers in 1993 will jump straight in with a DS-3 Asynchronous Transfer Mode-compliant Data Service Unit with the aid of interface specialist Digital Link Corp. Exactly the same company, as it happens, that Cisco is using as its partner. By the end of next year Wellfleet says that it will have reached its own phase two – with the Data Service Unit becoming internalised within the chassis. And then there’s Wellfleet phase three, where the company has a chassis able to switch Asynchronous Transfer traffic internally. One thing worth noting here is an assertion by Wellfleet that the company is looking at branching out from its traditional role as local network vendor to see whether its backbone nodes have the potential to be sold to public telecommunications operators as feeder switches. This can sound a bit rich coming from the company that described Cisco’s Advanced Program-to-Program Internetworking consortium as a distraction from its core business. However it illustrates just how far Asynchronous Transfer Mode is leading to the intermingling of the two separate markets.
