Section 4.1 Flashcards
Describe the actions primarily in the network-layer data plane
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.
Where is the network layer implemented in routers and hosts
routers - network core
hosts - network edge
What actions occur in a per-router control-plane approach?
- A router exchanges messages with another router, indicating the cost for it (the sending router) to reach a destination host.
- Routers send information about their incoming and outgoing links to other routers in the network.
Check all of the statements below about where (in the network) the network layer is implemented that are true.
The network layer is implemented in hosts at the network’s edge.
The network layer is implemented in routers in the network core.
Consider the travel analogy discussed in the textbook - some actions we take on a trip correspond to forwarding and other actions we take on a trip correspond to routing. Which of the following travel actions below correspond to forwarding? The other travel actions that you don’t select below then correspond to routing.
A car takes the 3rd exit from a roundabout.
A car waits at light and then turns left at the intersection.
A car stops at an intersection to “gas-up” and take a “bathroom break”
For each of the actions below, select those actions below that are primarily in the network-layer data plane. The other actions that you don’t select below then correspond to control-plane actions.
Looking up address bits in an arriving datagram header in the forwarding table.
Dropping a datagram due to a congested (full) output buffer.
Moving an arriving datagram from a router’s input port to output port
We’ve seen that there are two approaches towards implementing the network control plane - a per-router control-plane approach and a software-defined networking (SDN) control-plane approach. Which of the following actions occur in a per-router control-plane approach? The other actions that you don’t select below then correspond to actions in an SDN control plane.
A router exchanges messages with another router, indicating the cost for it (the sending router) to reach a destination host.
Routers send information about their incoming and outgoing links to other routers in the network.
Which of the following quality-of-service guarantees are part of the Internet’s best-effort service model? Check all that apply.
None of the other services listed here are part of the best-effort service model. Evidently, best-effort service really means no guarantees at all!
