A potential sender application wanting to establish a real-time channel knows the network address and port number of the receiving application.
The sending application makes an establishment request by issuing an Establish_Reque- st() library call, providing its QoS specifications as parameters. The MyRTP library builds an EstReq message and forwards it to the HEC on the sender host.
The HEC daemon, on receiving the EstReq message, updates its
local data structures, assigns an LCID to the connection and attempts to
establish the connection. Once all the phases are complete,
the HEC sends a EstReply message back to the calling application. This
informs the calling application about the status of the
request. This process is illustrated in Figure 7.
Figure 7: Sender Application Request