Forum Discussion

Altostratus

Jul 20, 2021

Solved

Virtual Server to maintain the same destination port to the backend

I have a requirement where have 4 backend server listening or port range 1603-1699 i.e. a total of 96 ports. The requirement is that the Virtual server should listen on the same ports and when the V...

application delivery

BIG-IP

iRules

spalande
Jul 20, 2021
- You can also keep port translation enabled if traffic destined on VIP port should be sent to same port on the pool member. This should work.

- You would need VIP defined on any port. Configure iRule to only allow specific range and discard traffic for other ports.

Please modify accordingly for start and end port range
when CLIENT_ACCEPTED { if {([TCP::local_port] >= <start port> && [TCP::local_port] <= <end port> ) } { return ) else reject }
- define pool with all 4 members and any port.

spalande

Nacreous

Jul 20, 2021

- You can also keep port translation enabled if traffic destined on VIP port should be sent to same port on the pool member. This should work.

- You would need VIP defined on any port. Configure iRule to only allow specific range and discard traffic for other ports.

Please modify accordingly for start and end port range

when CLIENT_ACCEPTED {    
    if {([TCP::local_port] >= <start port>  && [TCP::local_port] <= <end port> ) } {
       return   )
    else reject
}

- define pool with all 4 members and any port.

Umesh_Shetty
Altostratus
Jul 20, 2021
Sanjay ,

Thanks for your response. The iRule is good to define the required port range for VIP.

My question though is if we keep the translate port enabled how will it send traffic to the backend pool member on the same port ? I believe disabling prot translate will allow this behaviour
- spalande
  Nacreous
  Jul 20, 2021
  If pool member and VIP is listening on any port, F5 will by default send it to same port at the backend, irrespective of port translation settings. You can try it yourself.
- Umesh_Shetty
  Altostratus
  Jul 20, 2021
  Sanjay, many thanks for your response and help in this. I will test it in a couple of days and share the results