Hi to all,

Well I have one situation that may be interesting to all.

Our current configuration of Zimbra mail server is like this:

1. CentOS 6.3 + Zimbra 7.x on VMware ESXi server (VMware cluster for HA)
2. Currently connected to internet via mikrotik router and ISP1. (not HA, but in case of problems / not working router, I change only router and upload new config on it, max 15 min downtime ).

Problem is that ISP don't have stable link, because they are changing from cable to optic, and normally we don't have internet for couple hours. And they do it during working hour (by their words it will took some time for that works to finish) !!! Because my firm is doing a lot of mail communication with their partners, it is not good idea to have down mail server.

For now optic is to much expensive for us (it is more than 250Euros for 10/10 link :S, and they dont offer asymmetric up/down speed, only symmetric, cable is about 60euros for 16/1 link,), and my idea is to use 2nd ISP as backup / maybe load balance link (it is possible to configure Mikrotik, but I don't know how Zimbra will handle that), who is ADSL with speed 16/1 (cca 60 euros is that additional line, in that case with 2 ISPs I have theoretically 32/2 for 120 Euros ).

Bellow is shematic how I have think to do that:

Attachment 5297

For me only problem is how to set Zimbra and what to ask ISPs to configure (MX records and reverse DNS ?) to be able send / receive mails on another line (ISP2) in case that 1st line is out. Also my question is how will zimbra handle load balansing of WAN's ?

Thanks for help