Tandem Computers Inc’s San Jose-based Ungermann-Bass, Wellfleet Communications Inc of Bedford, Massachusetts and Fremont, California based Vitalink Communications have all come out with improved versions of their local area network bridge and router hubs. There are two linked themes running through all three announcements – the search for speed, and the importance of a fast backplane to link separate boards sitting in the chassis. The announcement also marks the re-emergence of the Reduced Instruction versus Complex Instruction Set wars, with Wellfleet choosing the Motorola Inc 68040 while the other two plump for RISC offerings from Intel Corp and Advanced Micro Devices Inc. The backplane provides a connection between separate routing or bridging boards in a chassis – if it is fast enough then traffic can travel between boards virtually as fast as it does when routed straight in an out of the same one, an important consideration when Fibre Digital Data Interchange traffic is running at 100Mbps. In addition, the backplane makes it possible to design fault-tolerant hubs with multiple redundancy: one board taking over from another if it is removed or damaged. Ungermann-Bass can claim a certain degree of foresight when it comes to backplanes since the company’s Access/One hub has had one since it was first designed in 1988. However, until now it has never been used: the existing range of Ethernet and Token Ring boards do not touch it, communicating instead through a slow bus connection. The company’s new range of boards, starting off with an FDDI offering, does use the fast PlusBus which is driven at 320Mbps by an Intel 80960CA RISC processor which is claimed to pack a hefty 150 MIPS. Each board has two of these so while one processor runs the bus, the other copes with Simple Network Management Protocol management and the bridging and routing. Measuring throughputs is always a business fraught with difficulties and quoted speeds should be taken with a pinch of salt, but Ungermann-Bass claims that the new Access/One boards can route at speeds of around 50,000 packets per second. Ethernet-to-FDDI RISC boards are due in December with FDDI-to-FDDI following up from the beginning of next year. Wellfleet, by contrast has not only had a backplane, but it has used it too. However in order to get the performance that it wanted for its new range of backbone nodes, the company has had to redesign it from scratch; Wellfleet’s existing products use a VMEbus running at 320Mbps – the same speed as Ungermann-Bass’s new offerings. The new Wellfleet kit, by contrast, has its backplane running at 1Gbps, with redundancy in the form of four independent channels. This new data highway has been dubbed the Parallel Packet Express and is based, says Wellfleet, on the IEEE Futurebus+ specification. the company is playing the fault-tolerant angle for all its worth, with boards that can be swapped in and out while the unit is running, and with no single point of failure. On paper the unit also looks very fast. Wellfleet claims effective throughputs of 480,000 packets per second; each board has a 33MHz Motorola 68040 processor – the power of the top-of-the-range Macintosh. Wellfleet has gone to a lot of trouble to defend its choice of processor against the RISC camp, insisting that the 68040’s on-board caching and higher levels of integration make it inherently better for implementing its type of architecture. The backbone node comes in two configurations: the smaller four-slot link node and the 13 slot concentrator node. Wellfleet says that it will continue selling its current products – targeting them at the smaller user. Vitalink’s new 6000 series multiprotocol bridge-routers fill the gap between the Ungermann-Bass and the Wellfleet products. Both use the Advanced Micro Am29000 RISC processor, but while the smaller 6400 has six slots and a 400Mbps backplane, the 6800 has 16 slots and doubles the backplane speed. Finally the company has come out with its low end, single board 6600. If that lot seems to fill most of the market niches, think again: 3C
om is ready with new multi-protocol, scalable hubs. – Chris Rose
