This part of ISO11898 specifies the characteristics of setting up an interchange of digital information between modules implementing the CAN data link layer. Controller area network is a serial communication protocol, which supports distributed real-time control and multiplexing for use within road vehicles and other control applications. This part of ISO11898 specifies the Classical CAN frame format and the newly introduced CAN Flexible Data Rate Frame format. The Classical CAN frame format allows bit rates up to 1Mbit/s and payloads up to 8byte per frame. The Flexible Data Rate frame format allows bit rates higher than 1Mbit/s and payloads longer than 8byte per frame. This part of ISO11898 describes the general architecture of CAN in terms of hierarchical layers according to the ISO reference model for open systems interconnection (OSI) according to ISO/IEC7498‑1 . The CAN data link layer is specified according to ISO/IEC8802‑2 and ISO/IEC8802‑3 . This part of ISO11898 contains detailed specifications of the following (see Figure2): logical link control sub-layer; medium access control sub-layer; physical coding sub-layer. There are three implementation options. They are the following: support of the Classical CAN frame format only, not tolerating the Flexible Data Rate frame format; support of the Classical CAN frame format and tolerating the Flexible Data Rate frame format; support of the Classical CAN frame format and the Flexible Data Rate frame format. The last option is recommended to be implemented for new designs. NOTE Implementations of the first option can communicate with implementations of the third option only as long as the Flexible Data Rate frame format is not used; otherwise, Error Frames are generated. There are opportunities to run implementations of the first option also in CAN networks using the Flexible Data Rate frame format, but these are not in the scope of this part of ISO11898 .