Discussing VxWorks network protocol stack from three aspects (1)

With the support of various network protocols and products, we have made more choices for our daily work. Here we will introduce relevant content such as the VxWorks network protocol stack. VxWorks is a high-performance, cutting-down embedded real-time operating System launched by Wind River, a US Wind River System Company. it is widely used in fields with high real-time requirements, such as communications, military affairs, aviation, and aerospace, with its excellent reliability and excellent real-time performance, such as satellite communication, military drills, ballistic guidance, aircraft navigation, etc. the VxWorks operating system includes process management, storage management, backup management, file system management, network protocols, and system applications. vxWorks only occupies a small amount of storage space and can be greatly reduced to ensure high system efficiency. it can be combined according to user requirements. Its open structure supports industrial standards so that developers only need to do the least work to design effective and suitable for different user requirements.

1. network protocol stack and MUX interface of VxWorks

The Network protocol Stack in VxWorks is called SENSScalable Enhanced Network Stack. SENS is developed based on the 4.4BSD TCP/IP protocol stack, including many protocols not available in the 4.4BSD TCP/IP protocol stack. In addition, SENS adds many new features when implementing some protocol functions, for example, the multicast function is added when the IP protocol is implemented. SENS protocol stack level 1 is shown.

The basic features of SENS are similar to those of the traditional TCP/IP network protocol stack. However, as shown in figure 1, the biggest feature of SENS is that the MUX layer is added between the data link layer and the network protocol layer. in SENS, the Network interface Driver is called ENDEnhanced Network Driver), that is, the enhanced Network Driver, which is at the data link layer. the IP layer and the TCP/UDP layer are collectively referred to as the network protocol layer. there is an application interface API between the data link layer and the network protocol layer). This interface is called MUXMultiplexer in SENS. MUX interface 2.

In the network protocol layer, VxWorks typically uses TCP/IP and supports other protocols). It typically uses Ethernet at the data link layer and also supports physical media for other data transmission, for example, the serial line access method used for long-distance connection, such as PPP. however, no matter what physical media is used, the network interface driver must use MUX to communicate with the data link layer of the network protocol layer, the network interface driver is the code for implementing the functions described by this abstract concept ).

In 4.3BSD, the network interface drivers and protocols of VxWorks are closely integrated. they communicate with each other by transmitting specific data structures. On the basis of MUX, they only interact with each other through MUX. for example, after receiving a packet, the network interface driver is not directly connected to the protocol layer. similarly, when the network interface driver is ready to send data to the protocol layer, the driver will call a function provided by MUX ). this function is used to transmit data to the action details of the protocol layer. the main purpose of MUX is to separate the network interface driver from the protocol layer, so that the network interface driver and the protocol layer are basically independent of each other. this independence enables loading of a new protocol or network interface driver. All existing MUX-based protocols can use this new network interface driver. Similarly, to add a new MUX-based protocol, the existing network interface driver can also use MUX to communicate with the new protocol.