multiple xbee cellular network

I’m working on a demo project with multiple xbee cellular nodes. Basically, I hope to make a star topology of this network, which means there is one and only one xbee cellular node as the master, all other nodes connect to it are client nodes. The master node will collect data from all client nodes and send data to client nodes too. what is the best way? (what communication mode should I choose, transparent, API or other? what protocol should I choose, TCP, UDP or other? Any other parameters should I change?)

PS: I do have each xbee cellular node with static IP address.

I would suggest using API mode and UDP.

I am confused when I read the documentation here:
So if the master node sends something to a client node, how will it receive the info? OR can the client node receive that?

Sorry about that. I forgot incoming sockets need to be using TCP and not UDP. So API and TCP would be preferred.