计算机网络课后习题指导 陕西师范大学 Correct operation client server HE10(u银Rxid) 华 BALANCE Insitiwhen theret eh moy Ho世aerid) k it valid uaerid) PASSKD〈gawd BALANCE ERR (not enough funds) P2.Equation 1.1 gives a formula for the end-to-end delay of sending one packet of length L over N links of transmission rateR.Generalize this formula for sending Psuch packets back-to-back over the N links 答：由一个分组端到端时延公式：dn-o-end=N可得，当连续发送P个分 组时，得到时延为：demd-to-end=N后×P。 P3.Consider an application that transmits data at a steady rate (for example,the sender generates an N-bit unit of data every k time units,where k is small and fixed).Also,when such an application starts,it will continue running for a relatively long period of time.Answer the following questions, briefly justifying your answer: a Would a packet-switched network or a circuit-switched network be more appropriate for this application?Why? b.Suppose that a packet-switched network is used and the only traffic in this network comes from such applications as described above.Furthermore.assume that the sum of the application data rates is less than the capacities of each and every link.Is some form of congestion control needed? Why? 答：a.电路交换网更适合所描述的应用，因为这个应用要求在可预测的平滑带宽上进行长期 的会话。由于传输速率是已知，且波动不大 因此可 以给 应用会话话路预留带宽而不会有 太多的浪费。另外，我们不需要太过担心由长时间典型会话应用积累起来的，建立和拆除电 路时耗费的开销时间。 b.由于所给的带宽足够大，因此该网络中不需要拥塞控制机制。最坏的情况下（几乎可能拥 2计算机网络课后习题指导 陕西师范大学 2 P2. Equation 1.1 gives a formula for the end-to-end delay of sending one packet of length L over N links of transmission rate R. Generalize this formula for sending P such packets back-to-back over the N links. 答：由一个分组端到端时延公式：d￾￾￾￾￾￾￾￾￾￾ = ￾ ￾ ￾ 可得，当连续发送 P 个分 组时，得到时延为：d￾￾￾￾￾￾￾￾￾￾ = ￾ ￾ ￾ × ￾。 P3. Consider an application that transmits data at a steady rate (for example, the sender generates an N-bit unit of data every k time units, where k is small and fixed). Also, when such an application starts, it will continue running for a relatively long period of time. Answer the following questions, briefly justifying your answer: a. Would a packet-switched network or a circuit-switched network be more appropriate for this application? Why? b. Suppose that a packet-switched network is used and the only traffic in this network comes from such applications as described above. Furthermore, assume that the sum of the application data rates is less than the capacities of each and every link. Is some form of congestion control needed? Why? 答：a. 电路交换网更适合所描述的应用，因为这个应用要求在可预测的平滑带宽上进行长期 的会话。由于传输速率是已知，且波动不大，因此可以给各应用会话话路预留带宽而不会有 太多的浪费。另外，我们不需要太过担心由长时间典型会话应用积累起来的，建立和拆除电 路时耗费的开销时间。 b. 由于所给的带宽足够大，因此该网络中不需要拥塞控制机制。最坏的情况下（几乎可能拥