计算机网络作业题(2011年12月版).doc

计算机网络作业题(2011年12月版)
第一章
1. Consider sending a packet of F bits over a path of Q links. Each link transmits at R bps. work is lightly loaded so that there are no queuing delays. Propagation delay is negligible.
a. Suppose work is a packet-switched virtual-work. Denote the VC setup time by ts seconds. Suppose the sending layers add a total of h bits of header to the packet. How long does it take to send the file from source to destination?
b. Suppose work is a packet-switched work and a connectionless service is used. Now suppose each packet has 2h bits of header. How long does it take to send the packet?
c. Finally, suppose that work is a circuit-work. Further suppose that the transmission rate of the circuit between source and destination is R bps. Assuming ts setup time and h bits of header appended to the packet, how long does it take to send the packet?
1、
a. ts+(F+h)/R*Q
(F+2h)/R*Q
+(F+h)/R
6. This elementary problem begins to explore propagation delay and transmission delay, two central concepts in working. Consider two hosts, A and B, connected by a single link of rate R bps. Suppose that the two hosts are separated by m meter, and suppose the propagation speed along the link is s meters/sec. Host A is to send a packet of size L bits to Host B.
a. Express the propagation delay, dprop, in terms of m and s.
b. Determine the transmission time of the packet,