LTM using own VIP as a pool member

First, thank you nitass. I choosed the data group because they had many VIPs and the LTM owners don't want hardcoded addresses. So, they will maintain this data with tmsh command "modify ltm data-group.......". Your suggestion about catch the event when load balance failed, can be useful. I knew about then problem "VIP to VIP" only when the eighteen VIPs are ready to work but did not. I kept the original configuration with priority group to be less labor intensive since it would only add a irule. I don't know about the process cost of my code, is this the cause of my discomfort, and I needed to keep the direction of traffic for the second VIP because I need to encrypt back. I guessed that someone had gone through a similar situation. So, thanks again.