Designing a network that will provide your company with sufficient capacity for the next five years is more challenging than it's ever been. Faster workstations and shorter product cycles make it difficult to anticipate what your needs will be toward the end of your network's lifetime. To provide some perspective, Network Computing draws on our real-world experience to offer you expert guidance for building your next-generation network. The decisions are yours, but the facts presented here will help you make your next infrastructure upgrade the best it can be.

At the LAN level, we recommend that you divide your network infrastructure decisions into four general categories: the network core, the interconnects to intermediate distribution frames, edge connectivity and server connectivity. Be aware that the choices you make in one area will limit your options in the others. Factors such as cost, distance between sites and necessary bandwidth must be assessed from the top down to determine what technologies to deploy at each site.

Assessing Your Core Infrastructure Many of today's networks are built around a collapsed backbone router, which often becomes the network bottleneck. Ethernet and FDDI are the most common interconnects between the collapsed backbone router and the rest of your network infrastructure. There are many options that will take the load off your core router and increase your overall network bandwidth. Switched Fast Ethernet and Gigabit Ethernet are the two most affordable technologies for the core of your network.

Many of the Gigabit Ethernet switches now available support advanced fault-tolerance features such as trunking and load-balancing, letting you create a multigigabit core network. These technologies make it possible to build a core with up to 4 gigabits of switched bandwidth. Several Gigabit Ethernet vendors also support Layer 3 routing. 3Com Corp.'s CoreBuilder 3500 supports IP and IPX routing in hardware, as well as AppleTalk routing in software. Cabletron Systems' new SmartSwitch Router supports IP and IPX routing in hardware, as does Foundry Networks. Bay Networks and Extreme Networks support IP routing in hardware. All of these vendors support OSPF in their backbone products.