Transmission time

Question

My approach is :

I calculated utilization first which is the time when link is active by total time 

U = transmission/ total time

Transmission = 1.048msec

Since no ack sort of policy is used so total time = transmission + propagation

U = 1.048/51.048 = 0.0205

Throughout = 0.0205 × 1GBps = nearly  161Mbps

What's wrong answer is B by the way

Comments

Transmission time =$\frac{8*10^{6}}{8*10^{9}}$=1mses.

Utilization=$\frac{T.T}{T.T+2*P.T}$=$\frac{1}{1+2a}$  [a=P.T/T.T]

                =1/101

Throughput=Utilization *Bandwidth

                   =(1/101)*8*$10^{9}$ bits/sec

                   =79.2Mbps

---

Sir thats ok bt how did u know that we are using acknowledgement policy in our protocol i.e. why 2tp why not tp only

---

u r asking about propagation time or transmission time.

Transmission time acknowledgement is very less compared to data size.

i.e) ACK size<< DATA size

T.T(ack)=ACK size/B.W  [ it is very less value so we are neglecting T.T at receiver side]

but propagation time for data and ack is same because it depends on velocity of medium but not ack size.

i.e) P.T (ack)=P.T(data)

---

No sir, i wanna ask that suppose a question says it's a token ring and between every two transmissions there is a gap of propagation time to transmit next frame in this case the formula would be like

U = transmission/ (transmission + propagation)

But in protocols like CSMA/ CD or some other policy like stop and wait where we need to wait for an ack to start a new transmission

I'm such case U = transmission/ (transmission + 2*propagation)

 

But in above case no such protocol is defined then how u took 2*propagation instead of only propagation.

And sir how to decide on such a general type question that which protocol it's talking about ?

---

i saw many problems in which Utilization(efficiency) is considered for both data and ackonwledgment.

if they particularly mention in the question  that ack of that packet is negligible then only use one way total time(T.T+P.T)

Remaining all case consider for both data and ack.

---

Ok Sir thank You