Forum Discussion

Michael_61103's avatar
Icon for Nimbostratus rankNimbostratus
May 17, 2012

Unable to communicate with Email Server from behind F5 BIGIP LTM v10



My clients sit on VLAN 10 while my web app servers are on VLAN 120. My F5 Big-IP LTM v10 is configured between them, which I am told this is a 2-ARM configuration.



My issue:


I cannot send mail from my web app servers. The email server is on VLAN 10. I am also having the same problem with DNS requests. If I try to do a nslookup, it fails to resolve the name I am searching for. My DNS Server is also on VLAN 10.





4 Replies

  • Hamish's avatar
    Icon for Cirrocumulus rankCirrocumulus
    Do you have network virtual servers (ip forwarding) setup to pass the traffic for non load balanced ports and targets?



  • Not sure what you mean exactly about non-load balanced ports and targets. We just purchased the Load Balancer(s) in November and we had an F5 engineer come out to configure and setup the F5.



    I have a few virtual servers setup to send various traffic to the node members. I have one that uses port 80, 554, 1521, 8554, 7980, and 445. All but the 1521 are listed as Standard Type, the 1521 port is a "Performance (Layer 4) Type.




  • Hamish's avatar
    Icon for Cirrocumulus rankCirrocumulus



    By non-load balanced traffic I mean anything where you want to be routed directly across the LTM. Such as your SMTP traffic. As the LTM isn't a router, in order to 'route' traffic you need to do it with a (Usually network) virtual server. The easiest way is one on port 0 (All ports), for all protocols, of type forwarding (ip).



    As long as the destination IP of the packet matches the network VS IP/mask it'll be forwarded based on the TMM routing table (i.e. to defined VLAN's with selfIP addresses).



    You can get more complicated from that to enforce fire walling etc. But a single VS on and port 0 would doit.



  • So if I understand you correctly, say I have a virtual server with ip address and have it assigned port 0. This will route all traffic that is not otherwise specified such as port 80.