Date: Tue, 01 Jun 1999 20:41:00 +0200 From: Poul-Henning Kamp <phk@freebsd.org> To: current@freebsd.org Subject: net.inet.tcp.always_keepalive on as default ? Message-ID: <20883.928262460@critter.freebsd.dk>
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Considering the number of hosts on the net today, which come and go with no warning and with dynamic IP assignments, I would propose that we disregard what the "old farts" felt about TCP keepalives, and enable the sysctl net.inet.tcp.always_keepalive as default. Setting this will make all TCP connections send a probing ACK every couple of hours if no other activity were present on the connection, this enables the TCP stack to figure out if the other end has gone or is still there. The typical symptom that you need this is that netstat shows many connections which have been standing there for any amount of time up to your uptime, simply because your machine is waiting to receive something from the other end, and for all practical purposes, "the other end" doesn't exist anymore. The argument against is that this will increas trafic and keep dynamic lines up when they should otherwise have been allowed to fall down. The former argument doesn't hold water, since we're talking about a TCP segment per hour (or less) per connection. The second argument falls on the same reasoning in my book, I don't know of any on-demand lines with a timeout longer than 10 minutes anyway. -- Poul-Henning Kamp FreeBSD coreteam member phk@FreeBSD.ORG "Real hackers run -current on their laptop." FreeBSD -- It will take a long time before progress goes too far! To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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