Specifications

Token Ring Desing Considerations
RADring
Installation & Operation Manual
6-2 Token Ring Physical Design 3/11/98 12:26
A typical design procedure consists of the following steps:
1. Define location of nodes
2. Define location of future nodes
3. Select the topology
4. Define location of wiring closets
5. Select the media to be used
6. Complete a cabling table
7. Calculate the worst-case scenario
8. If required, decide upon placement of repeaters and/or bridges
9. Verify network design
10. Calculate the cost per node
11. For large networks, select a new topology and repeat the procedure
12. Implement the design which best meets the objectives listed above.
The RADring, together with some of its modules can be used to simplify
steps 7, 8 and 9 and to shorten the design process. This section provides a
description of and guidelines to simplified network design using the RADring.
6.2 Token Ring Physical Design
Design Modules
When determining the physical feasibility of your Token Ring Network,
there are two basic limitations that have to be taken into account
•
Distance limitations
•
Station count limitations.
The design approach of many suppliers of token ring equipment is based on
the mechanical use of tables and/or arithmetic formulas provided by the
supplier, which define segment length, maximum number of stations and
wiring concentrators, etc. Although this approach seems simple, it can really
work only in relatively simple cases. It certainly does not allow optimization
of network design, nor does it provide any insight on the critical points of the
network layout.
RAD design method is based on the recognition that the factors limiting the
number of stations and the physical distance that can be covered by a token
ring are attenuation and jitter. The explicit approach recommended by RAD
allows the designer to identify critical areas and select an optimal and cost-
effective solution.
In addition, RAD provides special configurations which provide guaranteed
lobe/trunk distances and maximum station counts. These configurations
utilize repeaters, jitter attenuators, active access modules and passive access
modules to ensure simplification of the design procedure.