P4

Question 1

Why were switches itself originally not programmable (in SDNs)?

Answer 1

In the past, programable switches were very slow. The speed difference in the modern age is now very small.

Question 2

How high is the visibility of events at the data plane in SDNs?

Answer 2

Low

Question 3

How high is the visibility of events at the data plane in P4?

Answer 3

high

Question 4

Is P4 runtime reprogrammable?

Answer 4

yes

Question 5

What are the advantages of a programmable DP?

Answer 5

• Flexible data plane (DP)
  – Optimizable to specific network
  – Quick updates
• Hardware independent
• Potentially more robust
  – Only add the features you need
• Improved telemetry

Question 6

What are the disadvantages of programmable DP?

Answer 6

• Robustness/security
  – Introduce own bugs/security flaws in data plane
• More responsibilities for network operator

Question 7

Which component in P4 is responsible for QoS and telemetry?

Answer 7

Egress controller

Question 8

When is the checksum verified in P4?

Answer 8

After the parser

Question 9

In P4, which component populates the match tables?

Answer 9

The controller

Question 10

In P4, Which component defines the possible actions?

Answer 10

ingress & egress

Question 10

Can counters be read from the data plane?

Answer 10

No, only the control plane