nút trong mô hình, và dụ đại lý chỉ có một có thể được sử dụng với một ví dụ đại lý (hai người gửi từ xa có thể không giao tiếp với một máy thu duy nhất, hai người nhận phải được giao cho nút). Giao đại lý cho các nút, bạn phải sử dụng các lệnh đính kèm-agent. Trình tự trông giống như: | ns 327 node in the model and only one agent instance can be used with another agent instance two remote senders cannot communication with a single receiver two receivers must be assigned to the node . To assign agents to nodes you must use the attach-agent command. The sequence looks like set udp0 new Agent UDP new Simulator attach-agent n0 udp0 set null0 new Agent Null new Simulator attach-agent n1 null0 After the two agent objects are defined and attached to nodes you can create a connection between them using the connect command new Simulator connect udp0 null0 This creates the link between the UDP sender model and the NULL receiver model. After the agent connection is created you can use it to pass application data between nodes. Network Applications The application models simulate data traffic on the network. Just as in network emulation different types of network applications require different types of simulations. Network Simulator provides for several application models as well as allowing you to create your own using C classes. There are three main application class models used Application Traffic generates artificial traffic patterns. Application Telnet generates traffic simulating a normal Telnet session. Application FTP generates traffic simulating a normal FTP session. The Telnet and FTP applications produce data streams that you should be familiar with. The Telnet application sends short bursts of short packets simulating a remote terminal sending characters to a remote Telnet server. The server in turn sends a long burst of packets simulating a response from the server. The time between sessions is random simulating work being done on the client end before sending data. The FTP application simulates the sending of long data packets to the remote node and the remote node sending a short acknowledgment packet in return. Both the Telnet and FTP applications must be attached to a TCP agent to operate properly they both require acknowledgments from the .
