Cabletron Systems switches, bridges manual Intelligence in the Stack, Internetworking for Stacks

The Workgroup Approach

HubSTACK Interconnect Cables are connected in a particular sequence, from the OUT port of the first device in the stack to the IN port of the next. This arrangement is repeated from device to device as more stackable hubs are incorporated in the stack, as shown in Figure 3-3.

NOTE

If it becomes necessary to disconnect a HubSTACK Interconnect Cable from a device in the stack, disconnect the cable at the OUT port of the previous device in the stack to ensure proper termination of the Interconnect Cable chain.

Intelligence in the Stack

Once stackables became accepted in networks, users demanded management for them. The response from manufacturers was to make intelligent stackable devices. The design of intelligence and management capabilities for the stackable devices followed a path similar to the incorporation of management into modular chassis. Rather than requiring that all the stackables in a stack be intelligent in order for management functions to be performed, stackable intelligence is contained in only one device and is extended to the non-intelligent devices in the stack. Thus, only one intelligent device is needed to manage a full stack, keeping the costs of management down.

The basis of the intelligent stack is that the first device in each stack is the only one that requires this management intelligence. This intelligent stackable, or base, provides management services for the rest of the devices in its stack over the same connection that is used for stackable to stackable communications. The management traffic moves across the artificial backplane that is set up through the interconnect cables.

Internetworking for Stacks

As stackable devices and stacks are easy to design and configure, and often have a lower cost than modular networking chassis for these small-scale, simplistic network implementations, they are often found in large enterprise networks acting as fringe devices. These devices operate at the frontier areas of the network, where users connect to small shared network segments.

The use of stackable devices in these frontier workgroup environments often necessitates the use of a differing network technology, such as Fiber Distributed Data Interface (FDDI) or Asynchronous Transfer Mode (ATM) to make high-bandwidth connections to the enterprise network backbone or a central campus switch. The basic design of stackable hubs does not allow for the incorporation of different network technologies as does a modular networking chassis such as the Cabletron Systems Multi-Media Access Center, or MMAC.

3-6 Stackables