是作业里的题目，有做好了的几道需要大家帮忙确认下结果是不是对的，还有1，2道请大家指点下啊。
3. Suppose that between a sending host and receiving host there are three packet routers. The transmission rates between the sending host and the router, between routers and between the third router and the receiving host are TR1, TR2, TR3 and TR4, respectively. The links between the sending host and router R1; and router R3 and the receiving host are very fast. Other links are very slow. Assuming that the routers use store-and-forward packet switching, the links between R1 and R2, and R2 and R3 are congested (there are queuing delays) what is the total end-to-end delay to send a packet of length L?
我写的答案：the total end-to-end delay to send a packet of length L will be: L=TR1+TR2+TR3+TR4+R1+R2+R3
感觉不点不对。大家看看。
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6. Suppose there is a 10Mbps microwave link between geostationary satellite and its base station on Earth. Every minute the satellite takes a digital photo and sends it to the base station. Assume a propagation speed of 2.4 x （10）8 meters/sec:
a. What is the propagation delay of the link?
because propagation delay=d/s
hence, the propagation delay of the link is 10Mbps/2.4 x （10）8 meters/sec=41.7ms
b. What is the bandwidth-delay product, T x tprop?
41.7ms=0.0417sec
BDP=10Mbps x 0.0417sec / 8 =52.125Kb
c. Let x denote the size of the photo. What is the maximum value of x for the microwave link to be continuously transmitting?
A和B的算法正确吗。C需要帮忙下。。。
拜托了。。。
