Forum Discussion

pjcampbell_7243's avatar
Mar 04, 2009

BIG IP to load balance mail servers?

This may seem like an obvious question 1 way or the other but will the BIG IP properly load balance outgoing mail servers?

7 Replies

  • Sure.. it's just SMTP. You can configure a SMTP monitor, and virtual server listening on TCP/25.
  • Thanks. I did not see any reason why it wouldn't work but our network guy pointed out that it is more designed for web traffic. We'll give it a shot.
  • Deb_Allen_18's avatar
    Deb_Allen_18
    Historic F5 Account
    BIG-IP used to be fairly HTTP-centric, but that has changed. These days we support a broad range of TCP and UDP applications using similar checkbox features as those provided for HTTP.

     

     

    If you mean you want to LB your internal clients to a pool of internal mail servers handling outbound messages, then yes, that should be as trivial to implement as simple load balancing for web traffic.

     

     

    As jbaird mentions, you'd just configure your pool of mail servers, monitor them with an SMTP monitor, then apply that pool along with a tcp profile to a standard virtual server listening port 25 of the IP associated with the FQDN for outbound mail.

     

     

    hth

     

    /deb
  • I recently purchased a Big IP LB with ver. 4.5.12 and have had no luck load balancing SMTP. I am trying to do the same setup described. So far, I created a pool with the SMTP servers (added in this format 10.0.0.x:25), no SNAT, no NAT and LB type is Round Robin. *LB and SMTP servers are on the same VLAN.

     

    Then created a Virtual Server, with no Port or Address Translation and selected the SMTP Pool. Its been a while since I worked on one of these, am I missing a step or two, not doing it right?? Any help would be appreciated, I am on a time crunch.
  • ntsllc, that sounds about right. Are the servers set with a default gateway of the BIG-IP? If you're not using SNAT, the gateway would need to be the BIG-IP. Also, the client could not be on the same subnet as the servers.

     

     

    Aaron
  • Deb_Allen_18's avatar
    Deb_Allen_18
    Historic F5 Account
    with no Port or Address Translation

     

     

    You probably need to leave address translation enabled. In most LB scenarios, address translation (which in this case refers to destination address) is required: LTM accepts the traffic on the virtual address, then proxies to the real address. In your case, port translation doesn't matter since both VS and pool members are listening on the same port.

     

     

    HTH

     

    /deb