[969] in linux-net channel archive
Re: heavily-accessed site w/ random hangs on specific port... suggestions?
daemon@ATHENA.MIT.EDU (Andrew McNamara)
Wed Aug 23 18:18:24 1995
To: "Matti E. Aarnio [OH1MQK]" <mea@mea.cc.utu.fi>
Cc: linux-net@vger.rutgers.edu
In-reply-to: Your message of "Tue, 22 Aug 1995 12:23:49 +0300."
<95Aug22.122353+0200eet_dst.62998-2+21@mea.utu.fi>
Date: Wed, 23 Aug 1995 15:47:55 +1000
From: Andrew McNamara <andrewm@connect.com.au>
> When the jam happens, network monitors (persons with equipment
> on right spots on our ATM and FDDI nets) say that ftp.funet.fi
> gets TCP-SYNs (so, requests to create connection) into FTP
> control port, however it does not send TCP-ACK for it -> connection
> will not get estabilished. Simultaneous system call trace on
> that machine also shows that accept() does not happen.
>[...]
> I am beginning to wonder, if Linux network code does something
> wrong in the same way as BSD one ? (The OSF/1 networking code
> is clearly BSD code.) Or is it something more sinister ...
> ... the TCP/IP protocol is at fault ?
We have a similar experience here - but it usually effects SMTP (although
we are starting to see it on our web server as well).
I think it's a problem with the sockets interface model rather than TCP
itself - the listen(2) call only supports a finite number of
outstanding connection requests. In spite of what the manual entries
appear to say, connections requests in excess of the maxium supported
are simply ignored as you have seen.
We use SunOS 4.1.*.
--
Andrew McNamara (Systems Engineer)
connect.com.au Pty Ltd, Lvl 10, 56 Berry St, North Sydney, NSW 2060, Australia
Internet: andrewm@connect.com.au, Phone: +61 2 9959 5959, Fax: +61 2 9966 1960
