1. Where is transport-layer functionality primarily implemented? (Transport layer functions are
implemented primarily at the hosts at the “edge” of the network)
2. True or False: The transport layer provides for host-to-host delivery service?(true)
3. The transport layer sits on top of the network layer, and provides its services using the
services provided to it by the network layer. Thus it’s important that we know what is meant
by the network layer’s “best effort” delivery service. True or 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. (Correct! The network
layer’s best effort service doesn’t really provide much service at all, does it?)
4. What is meant by transport-layer demultiplexing? (Receiving a transport-layer segment from
the network layer, extracting the payload (data) and delivering the data to the correct socket.
5. What is meant by transport-layer multiplexing? (Taking data from one socket (one of possibly
many sockets), encapsulating a data chuck with header information – thereby creating a
transport layer segment – and eventually passing this segment to the network layer.)
6. True or False: When multiple UDP clients send UDP segments to the same destination port
number at a receiving host, those segments (from different senders) will always be directed
to the same socket at the receiving host. (true)
7. True or False: When multiple TCP clients send TCP segments to the same destination port
number at a receiving host, those segments (from different senders) will always be directed
to the same socket at the receiving host (false)
8. True or False: It is possible for two UDP segments to be sent from the same socket with
source port 5723 at a server to two different clients (true)
9. True or False: It is possible for two TCP segments with source port 80 to be sent by the
sending host to different clients (true)
, 10. True or False: On the sending side, the UDP sender will take each application-layer chunk
of data written into a UDP socket and send it in a distinct UDP datagram. And then on the
receiving side, UDP will deliver a segment’s payload into the appropriate socket, preserving
the application-defined message boundary (true)
11. Benefit udp (No retransmission delays , speed, suitable broadcast)
kekuragan (no guaranteed ordering of packets, No verification of the
readiness of the computer receiving the message, No protection
against duplicate packets., No guarantee the destination will receive all
transmitted bytes. UDP, however, does provide a checksum to verify
individual packet integrity.)
12. Udp header packet structure (source, destination port, length,
checksum,
13. Why is the
UDP header length field needed? (Because the payload section can be of variable length,
and this lets UDP know where the segment ends.)
14. Over what set of bytes is the checksum field in the UDP header computed over? (The entire
UDP segment, except the checksum field itself, and the IP sender and receive address
fields)
15. The receiver of a packet with a checksum field will add up the received bytes, just as the
sender did, and compare this locally-computed checksum with the checksum value in the
packet header. If these two values are different then the receiverknows that one of the bits
in the received packet has been changed during transmission from sender to receiver.
16. The sender-computed checksum value is often included in a checksum field within a packet
header.
17. A checksum is computed at a sender by considering each byte within a packet as a number,
and then adding these numbers (each number representing a bytes) together to compute a
sum (which is known as a checksum).
18. Compute the Internet checksum value for these two 16-bit words: 11110101 11010011
and 10110011 01000100 (01010110 11100111)
19. Compute the Internet checksum value for these two 16-bit words: 01000001 11000100
and 00100000 00101011 (10011110 00010000)
implemented primarily at the hosts at the “edge” of the network)
2. True or False: The transport layer provides for host-to-host delivery service?(true)
3. The transport layer sits on top of the network layer, and provides its services using the
services provided to it by the network layer. Thus it’s important that we know what is meant
by the network layer’s “best effort” delivery service. True or 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. (Correct! The network
layer’s best effort service doesn’t really provide much service at all, does it?)
4. What is meant by transport-layer demultiplexing? (Receiving a transport-layer segment from
the network layer, extracting the payload (data) and delivering the data to the correct socket.
5. What is meant by transport-layer multiplexing? (Taking data from one socket (one of possibly
many sockets), encapsulating a data chuck with header information – thereby creating a
transport layer segment – and eventually passing this segment to the network layer.)
6. True or False: When multiple UDP clients send UDP segments to the same destination port
number at a receiving host, those segments (from different senders) will always be directed
to the same socket at the receiving host. (true)
7. True or False: When multiple TCP clients send TCP segments to the same destination port
number at a receiving host, those segments (from different senders) will always be directed
to the same socket at the receiving host (false)
8. True or False: It is possible for two UDP segments to be sent from the same socket with
source port 5723 at a server to two different clients (true)
9. True or False: It is possible for two TCP segments with source port 80 to be sent by the
sending host to different clients (true)
, 10. True or False: On the sending side, the UDP sender will take each application-layer chunk
of data written into a UDP socket and send it in a distinct UDP datagram. And then on the
receiving side, UDP will deliver a segment’s payload into the appropriate socket, preserving
the application-defined message boundary (true)
11. Benefit udp (No retransmission delays , speed, suitable broadcast)
kekuragan (no guaranteed ordering of packets, No verification of the
readiness of the computer receiving the message, No protection
against duplicate packets., No guarantee the destination will receive all
transmitted bytes. UDP, however, does provide a checksum to verify
individual packet integrity.)
12. Udp header packet structure (source, destination port, length,
checksum,
13. Why is the
UDP header length field needed? (Because the payload section can be of variable length,
and this lets UDP know where the segment ends.)
14. Over what set of bytes is the checksum field in the UDP header computed over? (The entire
UDP segment, except the checksum field itself, and the IP sender and receive address
fields)
15. The receiver of a packet with a checksum field will add up the received bytes, just as the
sender did, and compare this locally-computed checksum with the checksum value in the
packet header. If these two values are different then the receiverknows that one of the bits
in the received packet has been changed during transmission from sender to receiver.
16. The sender-computed checksum value is often included in a checksum field within a packet
header.
17. A checksum is computed at a sender by considering each byte within a packet as a number,
and then adding these numbers (each number representing a bytes) together to compute a
sum (which is known as a checksum).
18. Compute the Internet checksum value for these two 16-bit words: 11110101 11010011
and 10110011 01000100 (01010110 11100111)
19. Compute the Internet checksum value for these two 16-bit words: 01000001 11000100
and 00100000 00101011 (10011110 00010000)
