Date: Tue, 11 Sep 2007 23:33:19 +0900 From: "Artem Kazakov" <kazakov@gmail.com> To: "FreeBSD Hackers" <freebsd-hackers@freebsd.org> Subject: TCP/IP redundant connections Message-ID: <f84a63260709110733n759224e4ufb475d9e7986da9d@mail.gmail.com>
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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.
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