Section 4.1

Question 1

Describe the actions primarily in the network-layer data plane

Answer 1

1.Dropping a datagram due to a congested (full) output buffer.
2. Moving an arriving datagram from a router’s input port to output port
3. Looking up address bits in an arriving datagram header in the forwarding table.

Question 2

Where is the network layer implemented in routers and hosts

Answer 2

routers - network core
hosts - network edge

Question 3

What actions occur in a per-router control-plane approach?

Answer 3

1. A router exchanges messages with another router, indicating the cost for it (the sending router) to reach a destination host.
2. Routers send information about their incoming and outgoing links to other routers in the network.