Date: Wed, 12 Sep 2007 15:12:59 +0300 From: Alexey Bobok <alexey.bobok@gmail.com> To: "freebsd-hackers-request@freebsd.org" <freebsd-hackers@freebsd.org> Subject: Re: freebsd-hackers Digest, Vol 233, Issue 3 Message-ID: <869014419.20070912151259@gmail.com> In-Reply-To: <20070912120008.AB75216A477@hub.freebsd.org> References: <20070912120008.AB75216A477@hub.freebsd.org>
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Здравствуйте, freebsd-hackers-request. I think it's not real because of implementation of TCP protocol (ACK numbers and so on). Maybe it's easier to use smthng like CARP to share 1 IP between multiple hosts, PFSYNC to share state tables of PF? > Send freebsd-hackers mailing list submissions to > freebsd-hackers@freebsd.org > To subscribe or unsubscribe via the World Wide Web, visit > http://lists.freebsd.org/mailman/listinfo/freebsd-hackers > or, via email, send a message with subject or body 'help' to > freebsd-hackers-request@freebsd.org > You can reach the person managing the list at > freebsd-hackers-owner@freebsd.org > When replying, please edit your Subject line so it is more specific > than "Re: Contents of freebsd-hackers digest..." > Today's Topics: > 1. TCP/IP redundant connections (Artem Kazakov) > 2. Announcement: Devilator 1.0a for FreeBSD (Borja Marcos) > ---------------------------------------------------------------------- > Message: 1 > Date: Tue, 11 Sep 2007 23:33:19 +0900 > From: "Artem Kazakov" <kazakov@gmail.com> > Subject: TCP/IP redundant connections > To: "FreeBSD Hackers" <freebsd-hackers@freebsd.org> > Message-ID: > <f84a63260709110733n759224e4ufb475d9e7986da9d@mail.gmail.com> > Content-Type: text/plain; charset=ISO-8859-1 > Hello Everyone! > For my research project I'm working on making some network services redundant. > And I have one idea, but I'm not so good and operating system > internals, so could you please tell what do you think. If it is > possible at all. > So, I have two hosts, which are all the same and they have some > network service which I need to make available all the time. This > service has some internal state, which is synchronized over private > connection. And at one time only one of the servers actually works > with clients, the other on is just sitting there and kept > synchronized. > The clients have persistent TCP connections to the server, and in case > of failure they make UDP broadcasts searching for server and then > reconnect. So basically there is no need to use IP-sharing between two > of them. But if the server fails, the client usually notices that > after some time-out (tcp keep alive time out I suppose) which is not > very good in some cases. > So I want to utilize IP-sharing and TCP-connection synchronization > (which is not yet implemented by anyone as far as I know). I want it > in case of failure seamlessly to switch to the other machine. As far > as the internal state is synchronized, if it is possible to > synchronize open connections as well(and all the low level stuff as > packet sequence numbers and so on) it would allow to make switch-over > to the back-up server in a matter of seconds, and the clients would > stay connected. > Is is possible to do so ? And if yes, how difficult would it be for a > person who has solid background in general-tasks programming, but no > experience with low level system programming ? And what are the > possible cave-eats of this approach? > Thank you. > Artem Kazakov. -- С уважением, Алексей Бобок mailto:alexey.bobok@gmail.com
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