2 ISP on one FreeBSD router

Paul Chvostek paul+fbsd at it.ca
Tue May 25 11:32:08 PDT 2004

On Tue, May 25, 2004 at 12:44:04PM -0400, Chuck Swiger wrote:
> Piotr Gnyp wrote:
> >My question is:
> >Is there a way to configure FreeBSD, so the NATed workstations will use
> >two ISP at once and in case of one ISP failure the whole traffic will be
> >put on one connection?
> Sure, that's a standard multihoming scenario.
> Get an AS number (www.arin.net) and set up BGP peering with your ISPs.

That's a good answer, but not for this particular question.

Piotr, if your FreeBSD router has an Ethernet interface bound to the IP
assigned by each ISP, then the easiest way to transfer your NAT from one
ISP to the other is probably simply to kill the existing natd and re-run
it with a different -n option.  This *will* have the effect of taking
down your NAT for the transition period -- this is unavoidable.

You could achieve the transition with a simple shell script that would
ping the "active" connection, and if it fails, `killall natd`, wait for
the process to die, and re-launch with the different command line opts.

The exact mechanics are left as an exercise for the reader.  Or the
consultant he hires.  ;)


  Paul Chvostek                                             <paul at it.ca>
  Operations / Abuse / Whatever
  it.canada, hosting and development                   http://www.it.ca/

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