在采用CSMA/CD控制方式的总线网络上，若τ=总线的单程传播时间，T=发送一个帧的时间（帧长/数据率），若定义a=τ/T，则总线的信道利用率最大值约为（）。
- A.见图A
- B.见图B
- C.见图C
- D.见图D
正确答案及解析
正确答案
解析
信道利用率达到最大的条件是：当一个站点发送的一个帧到达目的地后，某一个节点接着发送，介质没有空闲，也没有出现冲突的情况。此时，发送1帧的时间是T，帧的传播延迟是τ，总时间为T+τ，最大利用率为T/（T+τ）=1/（1+a）。
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