As I have noted many times in this column, a revolution is under way in LAN architecture. I coined the term LAN-in-a-Box to describe the technology that customers could use to move from distributed LANs and toward centralized hubs or routers (see BCR, August 1991, pp. 12-14; December 1991, pp. 12-14 and October 1992, pp. 10-12).
Many vendors now offer products--collapsed backbone routers, LAN switches and switching hubs--that support this architectural model. These terms are being used so diversely that it is time to revisit some of the basic principles and examine how the current products match up with customer requirements.
Better Performance
The basic reason for changing the way we construct our networks is our insatiable need for better performance. Even though our networks become larger and faster every year, congestion, interference and poor response times never seem to go away. The problems show up first on backbones and on servers, but eventually they affect more demanding clients as well. The next generation of Pentium chips, PowerPCs and other workstations, and their client/server and multimedia applications, will melt most conventional LANs.
Customers also want to reduce the number of ports/segments, in some cases down to one. While this is sometimes called LAN switching or portswitched Ethernet, a better term might be microsegmentation or dedicated LAN segments.
The fundamental issue is the architecture of the hub chassis and the cards that plug into it. The earliest hubs were single …
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