Homework: 22C:178 & 055:134
Computer Communications Fall 1998
[no due date]
Nothing to turn in for this assignment! This homework just provides
additional problems to consider in preparation for the second examination.
- (This is question 11 from the textbook.) Consider an ARQ protocol
that uses only negative acknowledgements (NAKs), but no positive
acknowledgements (ACKs). Describe what timeouts would need to be
scheduled. Explain why an ACK-based protocol is usually preferred to
a NAK-based protocol.
- Suppose a 500MB file is to be copied from host A to host B
over a five hop, store-and-forward path of nodes and links. Each
node uses the stop and wait protocol to send packets on its links,
with a packet size of 8KB, 24 bytes of which are reserved for the
header. ACKs are 24 bytes long. Each link has 100Mbps bandwidth,
and the propagation delay on each link is 500 microseconds.
What is the total time needed to copy the file?
- (This is question 24 from the textbook.) For a 100-Mbps token
ring network that uses delayed release (RAR), has a token rotation
time of 200 microseconds, and allows each station to transmit one
1-KB packet each time it possesses the token, determine the network's
maximum effective throughput rate (maximum effective bandwidth).
- Repeat the previous question, but calcuate the maximum effective
bandwidth if there is only one station that is the sender (all but
one station do not send any packet).
- What about if the immediate release strategy (RAT) is used
for the previous two questions? What difference will that make
in the answers?