When the IPv4 broadcast packet is encapsulated in the Ethernet frame, the destination MAC address is the broadcast MAC address FF-FF-FF-FF-FF-FF in hexadecimal (or 48 1s in binary).ĭHCP for IPv4 is an example of a protocol that uses Ethernet and IPv4 broadcast addresses. The IPv4 destination address is a broadcast address, 192.168.1.255. The source host sends an IPv4 broadcast packet to all devices on its network. This means that the address is permanently encoded into the ROM chip. Sometimes a MAC address is referred to as a burned-in address (BIA) because the address is hard coded into read-only memory (ROM) on the NIC. In such a case, it is necessary to modify the MAC address with a new NIC or make modifications by using software.
However, it is possible for duplicate MAC addresses to exist because of mistakes made during manufacturing, mistakes made in some virtual machine implementation methods, or modifications made using one of several software tools. It is the responsibility of a vendor to ensure that no two of its devices are assigned the same MAC address. Therefore, the Ethernet MAC address of that device would be 00-60-2F-3A-07-BC.
Cisco would configure the device with a unique vendor code such as 3A-07-BC. Because 1 byte equals 8 bits, we can also say that a MAC address is 6 bytes in length.įigure 7-8 The Ethernet MAC Address Structureįor example, say that Cisco needs to assign a unique MAC address to a new device, and the IEEE has assigned Cisco the OUI 00-60-2F. MAC addressing provides a method for device identification at the data link layer of the OSI model.Īn Ethernet MAC address is a 48-bit address expressed using 12 hexadecimal digits, as shown in Figure 7-7. The MAC address is used to identify the physical source and destination devices (NICs) on the local network segment. In an Ethernet LAN, every network device is connected to the same shared medium. If such conversions are required, convert the decimal or hexadecimal value to binary and then to convert the binary value to either decimal or hexadecimal as appropriate.
You might have to convert between decimal and hexadecimal values. Hexadecimal may also be represented using a subscript 16 or by using the hex number followed by an H (for example, 73H). Hexadecimal numbers are often represented by a value preceded by 0x (for example, 0x73) to distinguish between decimal and hexadecimal values in documentation. For example, in Figure 7-6, the binary value 0000 1010 is shown to be 0A in hexadecimal. When using hexadecimal, leading zeros are always displayed to complete the 8-bit representation. However, with the advent of quantum computing, the situation is likely to change.Figure 7-6 Selected Examples of Decimal to Binary to Hexadecimal Conversions Despite numerous attempts to use analog devices for computing, systems with ternary logic (ternary number system with the characters 0, 1 and 2), systems with binary logic currently occupy a dominant position. Due to the fact that we have only two characters to write a number (0 and 1), it has found wide application in electronic devices and computing. In the binary number system, everything is arranged in a similar way, only for writing numbers we have only two characters - 0 and 1. That is, to write numbers we have ten characters from 0 to 9, and the place of each character (position) indicates its weight - units, tens, hundreds, etc.
In everyday life, we are accustomed to using the base 10 decimal notation system for numbers. In this number system, numbers are written using two characters (which are usually the numbers 0 and 1). The binary number system is a positional number system with an integer base 2. The text is usually divided into parts called paragraphs, each paragraph is separated from the other, since it contains its own micro theme. The main idea of the text most often conveys the author's assessment of the subject of speech. The main, or main, idea of the text is what the author wanted to tell the readers, for the sake of which he wrote this text. Often the topic of a text is reflected in its title. The topic of the text is what the text says, that is, the subject of speech. Sentences in the text can be linked both lexically and grammatically. A text is a group of sentences that are united by one thought and topic. Actually, many animals are able to make sounds that have a certain meaning, but people have a whole system of signs called words.
One of the signs of people is the ability to communicate and express thoughts using sounds, which in ancient times led to the emergence of oral speech (language).