看得ccp150那本书的第118页说要知道Internet Transfer Latency，专门查了查，发现
以下网页。但面试的时候是不是只要假设如下即可，还是要有一个类似（内存可以假定
为4GB）一类的特定的数字啊？多谢
The speed of light imposes a minimum propagation time on all electromagnetic
signals. It is not possible to reduce the latency below
t=s/c_m
where s is the distance and cm is the speed of light in the medium http://rescomp.stanford.edu/~cheshire/rants/Latency.html http://en.wikipedia.org/wiki/Network_performance
