Sheikh,
You need to assign IP address to each physical server. If you only have ONE server you DO NOT need to assign IP address. The port assignments is all you need to get the clients to connect. Also make sure the BOBJ server is using an assigned IP address at the Server level and DOES NOT USE DHCP.
Another reason you may need to assign IP address is if you have serve with multiple NIC cards and want to control IP address the users connect through.
Regards,
Ajay