Forum Discussion

shishir_sontakk's avatar
shishir_sontakk
Icon for Nimbostratus rankNimbostratus
Feb 07, 2019

FQDN resolution and used in load balancing

Hello, I am working on requirement where I need to load balance traffic on FQDN. The FQDN is passed to F5 in HTTP header (Header name: backend-server). I have put iRule as below which is working fine.

when HTTP_REQUEST {

set lb_server [HTTP::header "backend-server"]
set lb_port [HTTP::header "backend-port"]
HTTP::header replace "Host" "$lb_server"
set dest [lindex [RESOLV::lookup @8.8.8.8 -a "$lb_server"] 0]
node $dest $lb_port

}

I would like to extend this further if FQDN is resolving in multiple IPs, use those IPs to load balance in round-robin or least connected fashion.

Would anyone know how this can be done? Any idea/suggestions?

Thank you.

application delivery
iRules
  • KeesvandenBos's avatar
    KeesvandenBos
    Icon for MVP rankMVP
    Feb 11, 2019

    Hi,

     

    Create a FQDN node and add the node to the load balancing pool.

     

    The FQDN node list will auto populate all the nodes that are returned by the DNS query; they are called ephemeral nodes. You need to make sure your DNS server is set to return all A records for this to occur.

     

    Cheers,

     

    Kees