Path: utzoo!attcan!uunet!lll-winken!ames!amdahl!rtech!wrs!hwajin
From: hwajin@wrs.wrs.com (Hwajin Bae)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: connect(2) timeout
Message-ID: <748@wrs.wrs.com>
Date: 17 Aug 89 18:57:12 GMT
References: <24692@iuvax.cs.indiana.edu> <747@wrs.wrs.com>
Reply-To: hwajin@wrs.wrs.com (Hwajin Bae)
Organization: Wind River Systems, Emeryville, CA
Lines: 17

Of course, the 10 minute keep-alive timeout scenario is only valid
if you don't get anything from the remote system after sending the
initial SYN packet.  If you get something back from the remote system
that cancels the keep-alive timeout, TCP will get into a bit more
complicated retransmission stage -- and subsequently will take
longer for connect() to actually time out.  TCP will keep on retransmitting
the SYN packet until it receives ACK/SYN for it.  TCP retransmission back-off
is based on the binary exponential algorithm 
	(1, 2, 4, 8, 16, 32, 64, 64, 64, 64, 64, 64, 64)
and the retransmission time will vary from 1 to 64 seconds and happend
upto 12 times.

-- 
Hwajin Bae
Wind River Systems
1350 Ocean Ave
Emeryville, CA 94608