Positioning of the Execution Environment (EE) in the protocol stack

As mentioned above, the execution environment should be implemented at a relatively low level in the protocol stack. When designing, it involves the selection of a specific layer, and the basic principle of selection is the efficiency and versatility of packet processing. Based on this, the execution environment should generally be implemented at the network layer or the transport layer. Since the transport layer commonly uses two different protocols, TCP/UDP, the implementation of EE at this layer must be implemented for TCP and UDP respectively, and the efficiency of the transport layer is relatively low, so it is not implemented at the transport layer.

Consider the following three options:

(1) Device driver layer;

(2) Generic device functions layer;

(3) IP layer. Although higher efficiency can be achieved if implemented at the device driver layer, it is necessary to modify (hacking) the standard device driver, and it is not possible to achieve a unified and universal implementation for different network devices. The device general interface function layer has a unified and universal implementation for all network devices, and its efficiency is relatively high; but it also has one disadvantage: it is necessary to directly modify the core code of the operating system, which will make it difficult to implement the runtime extension interface mentioned above, and its portability is also poor. This article decides to implement the execution environment at the IP layer. On the one hand, its efficiency is almost the same as that of the device general interface function layer; on the other hand, the runtime extension interface can be implemented more conveniently at this level, and this interface has good ease of use.

Design and Implementation of Active Network Execution Environment in Practical Network