Consider the following configuration:
- A pair of servers (named N1 and N2) hosting FTPS in passive mode
- A Kemp VLM hosting a VS in L4 Transparency mode for the pair of FTPS server
- Persistence is configured for the VS to ensure passive connections are sent to the same server as the active FTP session
Now consider the following situation:
- Client Bob connects via implicit FTPS port 990 to the VIP and is directed to server N1
- Client Bob lists directory contents opening a passive FTP and is returned the directory list
- A Kemp administrator Disables the Real Server N1
- Client Bob maintains his FTPS session to N1
- Client Bob starts a file transfer, because N1 was disabled in the load balancer, the passive session for the file transfer is sent to server N2
- The passive file transfer for Bob fails
Is there a good solution to this problem? Is there no method to ensure all TCP/UDP sessions for a specific IP are sent to the same real server even after it is disabled until all sessions end?
Any help is great. Thanks.