TCP session resetting | number of retransmission

[sarahr202]

Hi my old friends ( no pun intended).

I hope you  guys are doing fine. I am trying to find  the max number of retransmission for the same segment which once reached, will cause TCP sender to reset the TCP session.

I googled it and found one blog which says it is 5.  I am looking for some good reference which could corroborate this number.

http://blogs.technet.com/b/networking/archive/2009/08/12/where-do-resets-come-from-no-the-stork-does-not-bring-them.aspx

TCP Reset due to no response:

The next reset is a TCP reset that happens when a network frame is sent six times (this would be the original frame plus five retransmits of the frame) without a response. As a result, the sending node resets the connection. This is assuming that we have an established connection after the three way handshake. The number of retransmits before the reset is configurable, but the default is five.

Thanks

[Atul Choudhary · Accepted solution]

Hi, You are absolutely right here. It depends on platform which you are using. Windows do 5 retransmission before giving up until unless it is configured mannually.

The retransmission timer is  three seconds when a TCP connection is established in starting. However, it adjusts  timers on the fly to meet characterstics of connectection by using SRTT (Smoothed Round Trip Tme) calculations. Timer gets double when each retransmission happen. For example:

First restransmission time: x seconds

Second restransmission time: 2X seconds

Third restransmission time: 4X seconds

and so on..

Thanks