Hub descriptors are derived from the general USB device framework. Hub descriptors define a hub device and the ports on that hub. The host accesses hub descriptors through the hub’s default pipe.
集线器描述符派生自通用的 USB 设备框架。集线器描述符用于定义集线器设备及其端口。主机通过集线器的默认管道访问这些描述符。

The USB specification (refer to Chapter 9) defines the following descriptors:
USB 规范（参见第 9 章）定义了以下描述符：

• Device 设备描述符
• Configuration 配置描述符
• Interface 接口描述符
• Endpoint 端点描述符
• String (optional) 字符串描述符（可选）

The hub class defines additional descriptors (refer to Section 11.15.2). In addition, vendor-specific descriptors are allowed in the USB device framework. Hubs support standard USB device commands as defined in Chapter 9.
集线器类定义了额外的描述符（参见第 11.15.2 节）。此外，USB 设备框架也允许厂商特定的描述符。集线器支持第 9 章中定义的标准 USB 设备命令。