The following scenarios and questions are designed to draw together the content of the chapter and to exercise your understanding of the concepts. There is not necessarily a right answer. The thought process and practice in manipulating the concepts are the goals of this section. The answers to the scenario questions are found at the end of this chapter. The information used in these scenarios was adapted from the Cisco web page, "Cisco Configuration Guidelines."
The multinational company Gargantuan, Inc., has had a consultant completely readdress the company. The company used the private network 10.0.0.0 and created a hierarchical addressing structure. Refer to Figure 14-3 to see this addressing scheme.
Figure 14-3. Diagram for Scenario 14-1
The addressing of the network was a major project, with all the necessary pitfalls that attend such a large exercise. The network is now stable, and it is time to solve the problems that are being experienced as timeouts and network crashes.
The consultant assured the company that the resolution to the delays was the addressing scheme, but although the network is easier to manage, there has been no change in the congestion on the network. In addition, EIGRP appears to be losing routes from its routing tables, which is adding to the problem.
The consultant was correct: The network needed to be readdressed to allow EIGRP to function effectively. Unfortunately, the company did not read the report carefully and missed the other part of the solution.
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What needs to be done in addition to solve the addressing problems that make EIGRP inefficient? Give the configuration commands necessary to activate this solution on Router A.
The WAN is a Frame Relay cloud, and Router A is the hub in the hub-and-spoke configuration. Each VC is 56 kbps.
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Give the commands to configure Router A for EIGRP over this NBMA cloud.
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Give the commands to configure Router B for EIGRP over this NBMA cloud.
Given the configuration of EIGRP in Example 14-6, perform the tasks and answer the questions listed. The WAN has light user traffic and is a hub-and-spoke configuration, as shown in Figure 14-4.
Example 14-6. Scenario 14-2 Configuration for Router A
Router# show config interface Serial 0 encapsulation frame-relay interface Serial 0.1 point-to-point bandwidth 25 ip bandwidth-percent eigrp 123 90 interface Serial 0.2 point-to-point bandwidth 25 ip bandwidth-percent eigrp 123 90 ...
Figure 14-4. Diagram for Scenario 14-2
The 256-kbps access line to the hub has 56-kbps access lines to each of ten spoke sites. Each link has a Frame Relay CIR of 56 kbps. The access line to each router reflects the CIR. The access line to the hub router, Router A, is 256 kbps, but the CIR of the hub is the same as its access line.
From a Frame Relay perspective, a circuit is considered oversubscribed when the sum of CIRs of the remote circuits is higher than the CIR of the hub location. With ten links, each with a CIR of 56 kbps, this circuit is clearly oversubscribed.
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How much bandwidth has each circuit been allocated? Why was this value chosen by the administrator?
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What bandwidth utilization is available to EIGRP? Why was this value chosen by the administrator?
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If Router A fails, what would the effect be on the network?
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Is summarization possible only on the routers entering the WAN cloud, or is it possible on the networks not shown in the figure but on the other side of the routers? Give reasons for your answers.