[erlang-questions] Fault-Tolerant TCP/IP Servers

David Terrell <>
Fri Jul 11 18:56:04 CEST 2008


David Mercer wrote:
> Say I have a TCP/IP server (e.g., a web server, FTP server, etc.) 
> written in Erlang, and I want it to work through hardware failures; I 
> need at least two of them.  The problem is, clients are connecting to 
> the primary’s IP address, so when it fails, client connections are 
> refused instead of being rerouted to the secondary.  What is the Erlang 
> approach to solving this?
> 
>  
> 
> My thought is that you have the secondary detect the failure and send 
> the appropriate commands to the network to redirect traffic for the 
> primary server’s IP address to the secondary.  That’s my idea, but I 
> don’t really know if this is the appropriate solution, nor how to 
> implement something like this in Erlang.

OpenBSD's packet filter, called PF, has a tool called CARP to do just this.

You can read more on this here:

http://www.openbsd.org/faq/pf/carp.html



-- 
David Terrell
 (SMTP or XMPP)
http://meat.net/



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