Explanation of target _ and classfier _

Learning notes, which may not be completely explained, are recorded here first...

Target _ is the pointer to other instance objects stored by the agent. For example, when the application layer proxy is connected to the transport layer, the target _ in the class is assigned a pointer to the instance of the transport layer. In this way, target _-> Recv or target _-> send can be directly used to send packets to the next layer of the protocol stack.
The above mechanism is provided in N2, instead of using target _ to send the group.

The key point is to understand the idea of sending a group through NS2. to whom to send (object), you can call a function in this object. (In NS2. generally, it is a receiving or sending function, because the two functions are defined in the agnet base class and are also virtual functions, which is more convenient to use ).

Each node contains at least a few parts: an address or ID _. The initial value is 0. When a node is created, the simulated namespace is automatically added with 1. A neighbor linked list neighbor _; A proxy linked list of Agent _; a node type identifier nodetype _; and a routing module. TCL object: 1) Address classifier is used to determine the target address of the group and distribute incoming packets to the correct link .~ NS/classifier-ADDR. {H/CC}; 2) Port classifier (Port classifier) is used to determine the target agent of the group and distribute the incoming packets to the target proxy .~ NS/classifier-Port. {H/CC }.