The arrangement should in fact, work when the service is not transitive.
I can say that al least once a week for more than one hour the system is
not transitive, that is you, calling from exterior, can see only one of the
MX, but they can see themselves almost always.
so the arrangement would be the one i proposed.
every 5 minutes the MX17 would check MX10 to see if it is accepting
(space available and acceptable load), if not it would switch to "normal"
secondary.
BTW: how to implement delivery confirmations on the server ?
Il 30 Aug 2006 alle 0:20 Chris Lightfoot immise in rete
> On Tue, Aug 29, 2006 at 09:37:32PM +0200, Leonardo Boselli wrote:
> > Mi ides should be to redirect the port 25 of mx17 top the port 25 of
> > mx10, Using this arrangement calling either first or last mail
> > exchanger would end in connecting to the same computer, only using
> > different connections (more or less as having a dueal hosted main
> > server) Wpuld this work ? there is the risk that some sender try on
> > MX10 , have it busy, then instead of going to MX13 go directly to
> > MX17 that since is a rerouted to MX10 probably would refuse again ?
>
> see this thread:
> http://www.exim.org/mail-archives/exim-users/Week-of-Mon-20060522/
> msg00103.html
> for a similar idea (only accepting mail at a secondary if
> the primary is down, deferring it if the primary is up and
> would accept it, and rejecting it if the primary is up and
> would reject it). Note that this and similar solutions are
> strictly not correct since internet routing is not
> transitive (the fact that a client can see your secondary
> and your secondary can see your primary does not mean that
> the client can definitely see your primary) but in
> practice it seems to be an acceptable tradeoff in today's
> internet.
--
Leonardo Boselli
Nucleo Informatico e Telematico del Dipartimento Ingegneria Civile
Universita` di Firenze , V. S. Marta 3 - I-50139 Firenze
tel +39 0554796431 cell +39 3488605348 fax +39 055495333
http://www.dicea.unifi.it/~leo
