TCP window size and Router response

Mahesh Gohil · ‎04-11-2011

Hi all,

I am trying to understand relation of MTU with TCP window size.

Problem: One of my client having 40Mb end to end with latency of 66ms not able to go beyond 900kb throughput in one go.

According to BDP calculation the windowsize to be adjusted in 330,000 bytes in order to fully utilize 40mb of link. (let me know if I am wrong here).

Now the quesry is:

1/ in customer language: Why he is not able to reach 40mb and it is 7mb only at present.

2/ How router behave with different size of tcp window size.

3/ How to see what windowsize currently traffic is moving from router.

4/ Though client set higher window size (100,000) it not beneficial and result is same.

5/ WHy router is not reacting to higher window size.

I know there are lot of questions here but ultimate aim is to know how router react to higher tcp window size of end host.

Regards

Mahesh

IAN WHITMORE · ‎04-11-2011

Hi Mahesh,

Did you try looking at theses docs:

They should help you answer some of the questions.

Regards,

Ian

Mahesh Gohil · ‎04-11-2011

Hi Ian,

Thanks for your reply.

I already gone through the links given by you and many others but it didn't helped much in answering my query.

Sorry for this time..

Regards

Mahesh

Mahesh Gohil · ‎04-14-2011

Hi,

Anyone had any idea as what causes ftp throughput to lower

even tcp window size at end hosts is increased.

Regards

Mahesh