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B
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C
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Consider a distance vector protocol using split horizon and `periodic updates`. Assume that the link `B-C` fails. `B` and `C` update their local routing table but they will only advertise it at the end of their period. Select one ordering for the `periodic updates` and every time a router sends its distance vector, indicate the vector sent to each neighbor and update the table above. How many periods are required to allow the network to converge to a stable state ?
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Consider again the network shown above. After some time, link state routing converges and all routers compute the same routing tables as above.
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Consider the network shown in the figure below.
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Consider the same distance vector protocol, but now with `triggered updates`. When link `B-C` fails, assume that `B` updates its routing table immediately and sends its distance vector to `A` and `D`. Assume that both `A` and `D` process the received distance vector and that `A` sends its own distance vector, ... Indicate all the distance vectors that are exchanged and update the table above each time a distance vector is sent by a router (and received by other routers) until all routers have learned a new route to each destination. How many distance vector messages must be exchanged until the network converges to a stable state ?
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D
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Destination
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Distance vector protocols can operate in two different modes : `periodic updates` and `triggered updates`. `Periodic updates` is the default mode for a distance vector protocol. For example, each router could advertise its distance vector every thirty seconds. With the `triggered updates` a router sends its distance vector when its routing table changes (and periodically when there are no changes).
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E
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Host `A` uses a different flat address on each of its links
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Host `A` uses the same flat address for both links.
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If you compute the routing tables of all routers in this network, you would obtain a table such as the table below :
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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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Is it possible to achieve these paths and if so what are the required forwarding tables ?
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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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Let us now consider the transient problems that mainly happen when the network topology changes. For this, consider the network topology shown in the figure below and assume that all routers use a distance vector protocol that uses split horizon.
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`R1->R2->R4` and `R3->R2->R5->R4`
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`R1->R5->R4` and `R3->R2->R4`
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