4.1

Question 1

What are the functions of the network layer?

Answer 1

forwarding: move packets from router’s input to appropriate router output
routing: determine route taken by packets from source to destination

Question 2

What is a data plane?

Answer 2

• local, per-router function
• determines how datagram is arriving on router input port is forwarded to router output port
• forwarding function

Question 3

What is a control plane?

Answer 3

• network-wide logic

- determines how datagram is routed among routers along end-end path from source host to destination host

Question 4

What are the two control plane approaches?

Answer 4

-traditional routing algorithms:
implemented in routers
-software-defined networking (SDN): implemented in (remote) servers

Question 5

What are some example services for individual datagrams?

Answer 5

• guaranteed delivery

- guaranteed delivery with less than 40 msec delay

Question 6

What are some example services for a flow of datagrams?

Answer 6

• in-order datagram delivery
• guaranteed minimum bandwidth to flow
• restrictions on changes in inter-packet spacing