Cabletron Systems switches - Manual (Page 28)

The Workgroup Approach
3-6 Stackables
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.
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.
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.