The first two layers of the OSI model (or, the first layer of the TCP/IP model) specify standards for how data is transmitted between physical devices. The physical layer specifies physical standards for networking equipment and the networking medium (e.g. copper wire characteristics, voltages, pinouts, wifi frequencies). The data-link layer specifies how these media are used to achieve data transmission.
In this studio, you will:
Please complete the required exercises below, as well as any optional enrichment exercises that you wish to complete.
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One of the simplest methods for detecting data integrity errors is through the use of a parity bit. Consider a sequence of binary data that constitutes a message to be sent. In one parity bit scheme an extra bit is put at the end of a message- if the number of ones in the message is odd, then this last bit is set to one, so the overall number of ones in the message + parity bit is even. This is called an even parity encoding.
Suppose you use a parity-bit to protect an 8-bit message. How many bits do you send in total?
00001111 11101100 11111111 00000000
preamble - 7 bytes frame start - 1 byte MAC destination - 6 bytes MAC source - 6 bytes EtherType - 2 bytes Payload - up to 1500 bytes CRC error check - 4 bytes dead air - 12 bytes
The goal of Ethernet is to transmit data payloads, so the other parts of that transmission are considered to be overhead. How many bytes of overhead occur per Ethernet frame?