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Author(s) Quentin De Coninck
Deadline No deadline
Submission limit No limitation

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Routing in virtual circuit networks

Consider the following virtual circuit network.

https://inginious.org/course/cnp3-hackathon/virtual-circuit/virtual-circuit-net.png

The nodes have the following forwarding tables. If the index of the packet is not in the table, the router stops forwarding the packet.

R1's forwarding table:

Index Next Hop Next Label
0 R2 0
1 R2 1
2 R4 2

R2's forwarding table:

Index Next Hop Next Label
0 R5 0
1 R3 0
2 R5 1

R3's forwarding table:

Index Next Hop Next Label
0 R5 0
1 R6 /

R4's forwarding table:

Index Next Hop Next Label
1 R1 0
2 R2 2

R5's forwarding table:

Index Next Hop Next Label
0 R6 /
1 R4 1

Any packet arriving at R6 stops being forwarded.


Question 1: Starting with label 0

If the router R1 receives a packet with label 0, what is the path followed by the packet? Enter your path response as a sequence of the node identifiers separated by commas (e.g., R2,R1,R3). Start your answer with R1. If the packet loops indefinitely inside the network, answer by loop.

Question 2: Starting with label 1

If the router R1 receives a packet with label 1, what is the path followed by the packet? Enter your path response as a sequence of the node identifiers separated by commas (e.g., R2,R1,R3). Start your answer with R1. If the packet loops indefinitely inside the network, answer by loop.

Question 3: Starting with label 2

If the router R1 receives a packet with label 2, what is the path followed by the packet? Enter your path response as a sequence of the node identifiers separated by commas (e.g., R2,R1,R3). Start your answer with R1. If the packet loops indefinitely inside the network, answer by loop.