Sending data across LAN using VB.Net

Question

Hi there,
i am developing a project that needs to send data back and forth between two PCs in a network. i am using vb.net to accomplish this and i have this problem.

i want both applications to be servers as well as clients at the same time. This is because i need both applications to run on a seperate computer and allow both of them to send and receive data any time the application wants without being a server to begin a connection. how can i accomplish this in vb.net.