Ethernet framework
Since a bit is an alternating sequence of one and two’s, a preamble comprises of seven bytes of the bits. To accomplish computer networking by the use of an Ethernet framework, the use of a data link layer protocol data unit is needful. The data link layer protocol data unit is under the transport mechanism of the Ethernet physical layer. Before the Ethernet frame, there is a preamble together with a start frame delimiter. The two make the Ethernet frame at the physical layer. A start frame delimiter is essential in providing synchronization in the byte level, which marks a new incoming frame. The start frame delimiter is a 1-octet or in other words, 1-byte value marking the closure of a preamble. The making of a start frame delimiter is in a way that it breaks the bit pattern of a preamble together with the signal to start an actual frame.
Just after a start frame delimiter, there is a destination MAC address. A source MAC address is a 6-byte field containing the MAC address of a source machine. For a source address, zero is the least significant value of a bit in the first byte.
Although 2-byte or 16 bit hold values up to 65534, there are limitations in using Ethernet networking. Values below 1501 are used to show the size of the payload in octets. Values above 1535 indicate the type of protocol encapsulated in the payload of a frame, thus making an ethertype field two-octet long. The purpose of both the Ethernet II frame and pure IEEE 802.3 frame is an encapsulation of data. Ethernet (IEEE 802.3) Frame starts with a 7-byte preamble, a 1-byte start of frame delimiter, a 6-byte destination address, a 6-byte source address, a 2-byte length field, the data itself and lastly a 4-byte cyclic redundancy check. The size of the Ethernet IEEE 802.3 frame varies between 64 bytes to 1518 bytes as its data length varies between 46 bytes to 1500 bytes. The determination of the size of the Ethernet II frame is by the length, which is 2-bytes.
A-frame check sequence looks for corrupted data on the receiver side in a communications protocol. There is a code integrated into the frame that detects errors. Since all computer coded systems such as bits and bytes are vulnerable to errors deriving from various internet sources, there is a need to check for these errors. The design of the frame check sequence is that it contains a number calculated by the source node per the data in the frame. The addition of the number at the end of the frame makes it possible for recalculation and comparison made with the frame check sequence number in the frame. The difference between the two numbers depicts an error.
The minimum size of the standard Ethernet II is 64 bytes, while its maximum size is 1518 bytes. Later, for virtual local area network tagging, the maximum value is increased to 1522 bytes.
The maximum payload size of a regular Ethernet frame is 1500 octets. A payload is the body of a packet of data in networking. The contents of the payload include the following. The header, which contains the protocol information in addition to the source and destination address, are both essential in payload delivery. Another one is the flag or the data link layer frame, which marks the end of the data frame. The payload field has actual data.