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Scenario 1 69
Scenario Answers
Answers to Scenario 1
1
What technical issues must be taken into account when designing the network
infrastructure between the dormitories and the main campus?
Network contention is an issue. When the students at ZIP attach to the same segment, they
share the segment's bandwidth. If the sharing is significant, the network will be impacted.
The poor performance of the existing LAN is very likely due to users contending with
other users for network bandwidth. These demands on a shared network cause collisions
that result in overall poor performance for all users on the LAN. Collisions are inherent in
Ethernet design. As collision rates increase, network response hits a point of diminishing
returns, and user complaints increase. Also, collisions consume bandwidth.
Broadcasts are another issue on the shared LAN. Broadcasts consume bandwidth and
impact CPU processor performance. Every computer on the segment must process each
network broadcast.
2
What backbone would you recommend for the dormitories? (Each dormitory has seven
floors.) Why?
Distributed backbone (see Figure 2-8). Distributed backbone lets each switch distribute
signals to each campus floor. Because each floor has its own switch, troubleshooting is
made simpler, and there is no single point of failure.
Figure 2-8
Distributed Backbone
7th Floor
6th Floor
5th Floor
4th Floor
3rd Floor
2nd Floor
1st Floor
Si
87200333.book Page 69 Wednesday, August 22, 2001 2:18 PM