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This is an unpolished draft of the third edition of this e-book. If you find any error or have suggestions to improve the text, please create an issue via https://github.com/CNP3/ebook/issues?milestone=2 or help us by providing pull requests to close the existing issues.
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Building a network
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Multiple-choice questions
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Open questions
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In your daily life, you also use hierarchical and flat address spaces. Can you provide examples of these two types of addresses and discuss the benefits of using a hierarchical or flat addressing space in their particular context ?
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The network below uses port forwarding with flat addresses. The network boots and all hosts start one after the other. Explain at each step how the packets are forwarded and how the port forwarding tables of the network nodes are modified. Host `C` sends a packet to host `B`. Some time later, host `A` sends a packet to host `C`. Finally, host `B` sends a packet to host `A`.
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Same question as above, but the network is modified as shown in the figure below.
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Routing protocols used in data networks only use positive link weights. What would happen with a distance vector routing protocol in the network below that contains a negative link weight ?
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When a network specialist designs a network, one of the problems that he needs to solve is to set the metrics the links in his network. In the USA, the Abilene network interconnects most of the research labs and universities. The figure below shows the topology of this network in 2009.
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The Abilene network
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In this network, assume that all the link weights are set to 1. What is the paths followed by a packet sent by the router located in `Los Angeles` to reach :
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the router located in `New York`
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the router located in `Washington` ?
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Is it possible to configure the link metrics so that the packets sent by the router located in `Los Angeles` to the routers located in respectively `New York` and `Washington` do not follow the same path ?
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Is it possible to configure the link weights so that the packets sent by the router located in `Los Angeles` to router located in `New York` follow one path while the packets sent by the router located in `New York` to the router located in `Los Angeles` follow a completely different path ?
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Assume that the routers located in `Denver` and `Kansas City` need to exchange lots of packets. Can you configure the link metrics such that the link between these two routers does not carry any packet sent by another router in the network ?
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In the five nodes network shown below, can you configure the link metrics so that the packets sent by router `R5` to router `R1` use link `R3->R1` while the packets sent by router `R3` use links `R3->R2` and `R2->R1`?
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In the five nodes network shown above, can you configure the link weights so that the packets sent by router `R5` (resp. `R4`) follow the `R5->R3->R1` path (resp. `R4->R2->R3->R1`) ?
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Consider the network shown in the figure below.
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Assuming that the network uses source routing, what are the possible paths from `R1` to `R4` ?
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