Operation
12
Increasing Maximum
Network Length
A bridge may be used to link sub-networks serially in the same way a
repeater is used. Figure 7 shows this use of the cascaded-bridge topology. The
maximum network length only applies to individual sub-networks, so that the
overall network length is not bound by any limit. Since there are practical
limits on how many bridges can be used in this manner, however, each bridge
introduces a small delay in forwarded traffic.
Exceeding Maximum
Number of Stations
The maximum number of stations attached to a single network is 1,024. As
more stations are added, the number of collisions increases and performance
degrades. Bridges can be used to solve this problem. Although there is
effectively no limit on the number of nodes that can be attached to a bridged
network, there are some practical considerations. Once again, this is due to
the delay introduced by each bridge through which a frame passes.
Improving Network
Performance
In one way or another companies are divided into groups. Network users can
be considered in terms of natural clusters or workgroups. At one level there
may be separate divisions and within a division there are usually teams of
people associated with a project or department. When placing new bridges,
you can take advantage of natural clustering to provide dramatic network
performance improvements.
The important thing to realize about natural clusters is that the
communication among members of a group produces a much higher volume of
network activity than communication between groups. Communication
within groups includes inter-personal communication as well as transfer of
data between computers. Although groups must be able to communicate with
each other, inter-group communication produces less traffic.
Placement of Bridges.
The key to effective use of bridges is to find the
boundaries between workgroups within your organization and to split the
network by adding bridges at natural boundaries between different groups.
Network traffic within each workgroup is isolated by a bridge and has no
effect on the overall network. When computers from different groups need to
communicate, bridges allow them to do so as if they were one network.
Figure 7: Extending Network
Length
Sub-network A
Sub-network B
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