Ian Eiloart escribió: > > > --On 9 November 2007 13:27:48 +0100 Adrian Chapela > <[EMAIL PROTECTED]> wrote: > >> Ian Eiloart escribió: >>> >>> >>> --On 9 November 2007 12:50:43 +0100 Adrian Chapela >>> <[EMAIL PROTECTED]> wrote: >> >>> Provision of IP failover is highly dependent on the platform that >>> you're using. It's not required for MX availability, because remote >>> servers will try all your advertised servers. It is required for MSA >>> availability, because MUAs will not. >> Yes you are right, but if you have clients locally on your company, they >> must connect to a smtp server and DNS round robin it isn't the best >> solution to get hight availability (IMHO). > > That depends what you mean by "client". If you mean an MTA attempting > to relay, then round robin should do reasonably well at low cost. If > you mean mail user agents (MUAs) then round robin doesn't help at all, > as I said. I am talking about MUAs > > Absolutely right - DNS round robin does nothing for MUAs (mail > clients). Mail clients won't attempt to connect to a second IP > address, so DNS round robin does nothing to achieve high availability > at all. It merely serves to provide load balancing. Actually, if that > makes the servers more capable, then you may get some small > availability gains. > > So, for high availability you need to ensure that every IP address in > the round robin is highly available. For that, you need IP failover. > For MX hosts, you don't need IP failover because remote servers should > try all the available IP addresses. Yes... > >>> >>> We use MacOSX servers. OSX has a reasonably easy to configure IP >>> failover mechanism, as long as you only have two servers. When we went >>> beyond two servers, we deployed spread and wackamole which make >>> failover configurations for any number of servers trivial. For >>> example, we have 12 imap server IP addresses, to ensure good load >>> balancing with either 4, 3 or 2 available hosts. Wackamole simply >>> needs to know what the addresses are, and endeavours to share them out >>> equally among available servers. >> Yes.. it sounds perfect... >>> >>> <http://www.spread.org/> >>> <http://www.backhand.org/wackamole/> >> >> Best regards. > > >
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