CSMA/CD

Question

try this....

Answer 1

for csma 

length >=2*L*B/d

2500 KB>=2*2*1000*2*10⁶/d

we get d=39062.5

they have considered 1kB=1000B

so  ans is given as 40000

Comments

but 1kB = 1024B  ?

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yes and ans will be 39062.5

Answer 2

Here B=20*10^6 bits ,d=20*10^3,L=2500*8*10^3

we know that  length (L)>=2*Tp*B

so,

2500*8*10^3 >= 2 *  20*10^3  *20 *10^6 / v  (since Tp= d/v)

so v = 40000 m/s