Add a Point-to-Point Link 
In the Scalable Network Modeling Interface, a point-to-point link models a communication channel between two STK objects (or nodes).
To define the point-to-point link, right-click Connections and select Add Link... from the right-click menu. Make the following selections on the Add Link window and click OK.
IPv4Address. 32-bit address that identifies the interface in the IPv4 network. An example IPv4Address is 190.0.0.0.
Subnet Mask. IPv4 subnet mask assigned to the interface. All interfaces on a subnet share a 32-bit subnet mask. An example subnet mask is 255.255.255.0.
Link From. Select the starting STK object from the drop-down list.
Link To. Select the ending STK object from the drop-down list.
Assign IP address to match base IP. Creates an IP address for this link that matches the IPv4Address.