Computer networks

Question

What is RTT in Computer networks?

A)Transmission delay + 2*propogation delay

B)2*propogation delay.

Comments

https://en.wikipedia.org/wiki/Round-trip_delay_time

Answer 1

RTT actually is a 2 way latency and actually depends upon scenario..One way latency is defined as :

Latency = Propogation delay + Transmission delay + Queuing Delay

Now based on the data size which we are considering , we can have different interpretation of R.T.T :

Case 1 :

If the message contains only one bit and we are talking about a single link (as opposed to a whole network), then the Transmit and Queue terms are not relevant, and latency corresponds to the propagation delay only.
 

So in that case R.T.T = 2 * Propogation delay

Case 2 : 

Say we are not considering the queuing of packets,so queuing delay is ignored and hence our expression for R.T.T. reduces to :

R.T.T.  =   2 * Propogation delay  + Transmission Delay_data  + Transmission Delay_{acknowledgement}

Again acknowledgement size is negligible often , so we write :

R.T.T.  =   2 *  Propogation delay  + Transmission Delay_data  

Hope this helps..

Comments

Thank you.