The Gateway to Computer Science Excellence
First time here? Checkout the FAQ!
x
239 views
Consider a TCP connection with 10 ms round-trip time, max segment size = 2 KB, receiver window = 64 KB. Suppose packet #4 timed out and all other transmissions were successful. RTO value is 50 ms. Calculate the time required to reach the receiver window size. Assume RTT is fixed.
posted Aug 25, 2016 in Computer Networks by Junior (767 points) | 239 views

2 Comments

 

Solution
Initially, cwnd = 2KB,
ssthresh = 64 KB
ACK #1 at RTT 1, cwnd = 4 KB,
ACK #2 at RTT 2, cwnd = 8 KB,
ACK #3 at RTT 3, cwnd = 16 KB
#4 is lost at RTT3+RTO = 30 + 50 =80 ms
ssthresh = 16/2 = 8 KB, cwnd = 2 KB
retransmit #4
ACK #4 at RTT 1, cwnd = 4 KB
ACK #5 at RTT 2, cwnd = 8 KB
ACK #6 at RTT 3, cwnd = 8 KB
Since we reached sstresh, switch to
additive increase:
ACK #6 at RTT 3, cwnd = 9 KB
..
ACK #x at RTT x-3, cwnd = x+3 KB
..
ACK #61 at RTT 58, cwnd = 64 KB
RTT 58 = 580 + 80 = 660 ms
 

@Aantra in question it is given 4th packet is time out...and 4th packet is availble at RTT2
Quick search syntax
tags tag:apple
author user:martin
title title:apple
content content:apple
exclude -tag:apple
force match +apple
views views:100
score score:10
answers answers:2
is accepted isaccepted:true
is closed isclosed:true

32,732 questions
39,308 answers
110,278 comments
36,732 users