LB'ing FTP

we currently have 2 pools and two vips that were designed to take ftp traffic 20/21.

 

 

From what I understand about the issue from the users is that they can connect, but are unable to perform commands like "ls" once connected. As I understand the ftp process.. port 20 is DATA and is the problem here. I noticed that the monitor for port 20 on the Big-IP is down.

 

 

anyone any work around for load balancing port 20/21 ??