Section 3.1

Question 1

Where is transport-layer functionality primarily implemented?

Answer 1

Transport layer functions are implemented primarily at the hosts at the “edge” of the network.

Question 2

True or False: The transport layer provides for host-to-host delivery service?

Answer 2

True

Question 3

Name 5 services that are provided by the TCP protocol.

Answer 3

1. Reliable data delivery.
2. A byte stream abstraction, that does not preserve boundaries between message data sent in different socket send calls at the sender.
3. A congestion control service to ensure that multiple senders do not overload network links.
4. In-order data delivery
5. A flow-control service that ensures that a sender will not send at such a high rate so as to overflow receiving host buffers.

Question 4

What service is provided by the UDP protocol?

Answer 4

A message abstraction, that preserves boundaries between message data sent in different socket send calls at the sender.

Question 5

True of false: The network layer’s best-effort delivery service means that IP makes its “best effort” to deliver segments between communicating hosts, but it makes no guarantees. In particular, it does not guarantee segment delivery, it does not guarantee orderly delivery of segments, and it does not guarantee the integrity of the data in the segments

Answer 5

Correct! The network layer’s best effort service doesn’t really provide much service at all, does it?