Update Clause 4.2 Product architecture to revised structure (was 4.3)

A virtual network interface presents a network device driver interface to the rest of the host software. It may encrypt, filter, transform, route, discard, or otherwise modify network traffic entering the interface. The network traffic may then be directed to another virtual network interface on the same host, to another executable on the host, or to a physical network interface.

## 4.3 Product architecture

## 4.2 Product Architecture

### 4.3.1 Overview

<mark>Editor’s Note: This clause shall depict reference architectural patterns of products in this category, focusing on the architecture of the product itself and not the product as part of its operational environment or a larger ecosystem. The goal is to clearly indicate components, RDPS and their inter-relationships.</mark>

<mark>Editor’s Note: If the product category consists of multiple distinct product types, the reference architecture for each product type shall be drawn up separately for maximum clarity.</mark>

<mark>Editor’s Note: The diagram(s) shall be clearly labeled and accompanied by a short description of the main flows and components.</mark>

### 4.2.1 Overview

For the purposes of this standard, a physical network interface consists of:

A virtual network interface consists of a device driver only.

### 4.3.2 Types of network interface

### 4.2.2 Types of network interface

A network interface connects via a communications bus to the host. The host transmits to and receives data from the network by means of a device driver interface provided by the device driver for the network interface. A network interface might read and write the host memory directly and raise interrupts. It sometimes has more advanced features that allow it to power cycle the entire system, download files using simple protocols, and act as a simple boot loader.

![Figure 4.3.2-1: Physical network device architecture](media/physical_network_interface.drawio.png)

![Figure 4.2.2-1: Physical network device architecture](media/physical_network_interface.drawio.png)

**Figure 4.3.2-1: Physical network device architecture**

**Figure 4.2.2-1: Physical network device architecture**

A wired network interface transmits data via a specific physical medium such as Ethernet cable, fibre optic cable, coaxial cable or power lines. A wireless network interface transmits data in a manner that does not require a specific medium, such as radiofrequency waves or visible light communication through the air. A virtual network interface transmits data through software within the memory of a host system, sometimes across a software-defined network fabric.

A virtual network interface emulates the device driver interface of a network interface to a host's device driver API. Instead of a physical network interface, it may send and receive packets to a hypervisor, a container, another device driver, another part of the network stack, an application, or other software.

![**Figure 4.3.2-2: Virtual network device architecture**](media/virtual_network_interface.drawio.png)

![**Figure 4.2.2-2: Virtual network device architecture**](media/virtual_network_interface.drawio.png)

**Figure 4.3.2-2: Virtual network device architecture**

**Figure 4.2.2-2: Virtual network device architecture**

### 4.3.3 Device drivers for network interfaces

### 4.2.3 Device drivers for network interfaces

The device driver communicates with the host software or firmware by means of a network device driver API. This API abstracts the implementation details of the underlying network interface. Such network device driver API is typically defined by the host operating system or other software and is used by the host network stack to send or receive data through the network interface.