Hello,
Thank you for your comment.
Actually It is Linux Cluster. now I deploy ERs and ASCS with Linux HA solution. as I know there require two virtual IP address of ERs and ASCS.
Then as I know normally ERS doesn't need a IP address. but according to High Availability with the Standalone Enqueue Server - Standalone Enqueue Server - SAP Library, there has ERs clients. so if I need to configure a virtual IP address for ERs in HA. or I need to check if customer has requirement for ERS IP address first.
I thought normally ERs clients are connected to ERs server and ERs will connect to ASCS.
that's why if I want to deploy ERS and ASCS both are configure the instance as service of HA, I must have two virtual IP address. then is it wrong? 
Regards,
Jinkoo