"以太网基本帧结构与地址字段解析"

The chapter 11 of the Ethernet Access Controller (EMAC) block discusses the basics of the Ethernet frame structure, which is used for formatting frames for Ethernet communication. The frame structure includes various fields such as the Preamble and Start Frame Delimiter (SFD), Destination Address (DA), Source Address (SA), Type/Length field, Data field, and Frame Check Sequence (FCS). The Preamble is a 56-bit field consisting of alternating 1s and 0s, and the SFD field contains the sequence "10101011" immediately following the Preamble. These fields are used for synchronization purposes. Each frame contains two address fields: the Destination Address field and the Source Address field. The Destination Address field specifies the network node to which the frame is being sent, while the Source Address field specifies the network node sending the frame. An Ethernet address is 48 bits long and is usually represented using 12 hexadecimal digit pairs, with each pair representing a byte of information. When transmitted over a network, the byte order is from Most Significant Bit (MSB) to Least Significant Bit (LSB), while within a byte, the transmission order is from the least significant byte to the most significant byte. For example, an Ethernet address such as F0-4E-77-8A-35-1D is equivalent to the bit sequence 000011110111001011100111110101001101010001110110. In summary, the chapter provides a detailed explanation of the Ethernet frame structure and the various fields involved in Ethernet communication, laying the groundwork for understanding the EMAC data protocol and knowledge. Understanding the fundamentals of Ethernet frame structure is crucial for developing and implementing effective communication protocols and systems in Ethernet networks.