reset password
Author Message
talisunep
Posts: 140
Posted 02:49 Mar 19, 2013 |

hi Professor
Will you be posting the hw2 solutions online before the finals?

talisunep
Posts: 140
Posted 03:31 Mar 20, 2013 |

professor for the homework 2 solutions for 
question 4 at time 3T why is the congestion window still at 3 and not 4? shouldn it be incremented  on ack like 
the example from  ppt 13 slide 20?

http://www.calstatela.edu/faculty/hpguo/Teaching/Winter13/CS470/Homework/hw2/hw2_sol.htm

talisunep
Posts: 140
Posted 04:18 Mar 20, 2013 |

also for the slide 20 on ppt 13 at  at time 9D after 3 ack are repeated 666

the new sst become 3 (1/2 of cwnd )
and cw =1 
why is cw not 3 in this case?
by the congestion detection algorithmn it says for 3 ack  cwnd = threshold (new)

this has been implementd in the hw solution but not for the one done in class.. why is there a difference?
am i missing something in the formulae?

Attachments:
hensan
Posts: 23
Posted 10:54 Mar 20, 2013 |

Also, why is it that at time 3t is there only packet 5 sent and not 5 and 6.

talisunep
Posts: 140
Posted 14:12 Mar 20, 2013 |
hensan wrote:

Also, why is it that at time 3t is there only packet 5 sent and not 5 and 6.

 

thats because shes taken cw as 3 so packets sent should become  un ack-ed - cw = 3-2 = 1
but as per algorithm the cw should be +1 previous value for new segment 2 sent.... i dont know why its 3 it  should be 4

 

Last edited by talisunep at 14:14 Mar 20, 2013.
hensan
Posts: 23
Posted 16:45 Mar 20, 2013 |

At time 2t the value for cw should have been doubled since it is still in the slow start phase.

Slide 7 in chapter 13 says that cwnd increases by 1MSS each time one new segment is acked, but the next graph it shows that cwnd doubles for every acked segment. I'm not sure which one is correct?