The USB Communications Device Class Specification 1.1 contains general Communications Class
specifications, and details for seven device subclasses. That specification has been editorially reorganized
into a common USB CDC 1.2 specification [USBCDC1.2] and a set of subclass specifications. This should
help implementers understand what is necessary for each device subclass and facilitate specification
maintenance by the USB Device Working Group.
This document is one of those subclass specifications. It contains material technically identical to that
contained in USB CDC 1.1. It is intended to guide implementers of USB-connected devices of the types
listed in the following section.
This document specifies one device subclass intended for use with Communication devices, based on the
Universal Serial Bus Class Definitions for Communication Devices specification [USBCDC1.2]. It
supports Ethernet (IEEE 802.3) and similar devices.
The intention of this specification is that all material presented here is technically compatible with the
previous version of the USB CDC 1.1 Specification, from which it is derived. Numeric codes are defined
for subclass codes, protocol codes, management elements, and notification elements.
In some cases material from [USBCDC1.2] is repeated for clarity. In such cases, [USBCDC1.2] shall be
treated as the controlling document.
In this specification, the word ‘shall’ or ‘must’ is used for mandatory requirements, the word ‘should’ is
used to express recommendations and the word ‘may’ is used for options.