The Workgroup in the Larger Network 5-21

Network Design
• Simplified Troubleshooting - The device collapsed backbone, by connecting
the workgroups through a manageable device, provides not only simplified
troubleshooting, but the ability to detect some backbone faults before they
become network failures.
• Extensive Control - The device collapsed backbone provides the highest level
of network control. Workgroups and devices on the backbone can be included
or bypassed with the click of a mouse or through the use of a terminal session.
Physically adding workgroups to the network will still require the connection
of facility cabling and jumper cables, but, as with the standard collapsed
backbone, the usefulness of planning ahead cannot be over-emphasized.
One danger of the device collapsed backbone is the existence of a single point of
failure: the backbone device. If the backbone device fails, the backbone network
will not operate. For more information on single points of failure and avoiding
their creation in a network, refer to the Fault Aversion section of this chapter.
Choosing Backbone Technologies
The selection of a backbone technology is a similar process to the selection of
workgroup technologies. As with the selection of a workgroup technology, make
sure you are familiar with the operation of each type of technology, the strengths
and shortcomings of those technologies, and the special design considerations
that each technology imposes on the network. You may, again, wish to refer to the
training information of this Networking Guide for initial instruction.
The selection of a backbone technology requires a careful examination of the
needs of your facility and the ways that the various technologies and organization
styles can fit those needs. It is the job of the Network Manager or persons
designing the network to determine which factors of the network design are the
foremost requirements.
The determining factors in selecting a backbone network technology are the same
as those used in selecting workgroup technologies - performance (speed of
operation), reliability, ease of configuration, troubleshooting, and cost. In the
backbone network, it is quite common to plan far ahead, providing more
bandwidth than you think you will need. If this is done correctly, it will facilitate
the upgrading of the technologies of the outlying workgroup networks without
requiring an immediate rebuilding of the backbone network.
For this reason, once you feel you have selected a suitable technology, do further
research on that technology to resolve any questions about its operation or the
means by which a network is created using that technology. Contact your
Cabletron Systems Sales Representative for information, or read any of the
technical books available of the subject matter.