ccna 200 301 booksmart trailer (2019)

ccna 200 301 booksmart trailer (2019).Ethernet AddressingLet's take a look at how Ethernet addressing works. The MAC (Medium Access Control) address used here is burned into each Ethernet NIC (network card), although this address can be overwritten. The format of this MAC address, or hardware address, is hexadecimal and is 48 bits (6 bytes) in total.Figure 3.2 shows the 48-bit MAC address, with the purpose of these bits indicated.The OUI (Organization Unique Identifier) is assigned to each organization by the IEEE and consists of 24 bits (3 bytes). Each organization is then responsible for assigning the globally managed address (24 bits, or 3 bytes), and this address is unique among all NICs it produces (it should be unique, but - no one can guarantee it). Now to take a deeper look at this3.1 Reviewing the EthernetDiagram. The high bit is the I/G (individual/group) bit. When it is 0, we can assume that this is the MAC address of a device, and this address will likely be out in the source address field of the MAC header. When it is 1, we can assume that this is a broadcast or multicast address in an Ethernet environment, or a broadcast or functional address in a token ring and FDDI environment.The next bit is the global/local bit, or simply the G/L bit (which may also be referred to as the U/L bit, where U denotes global). When this bit is set to 0, it indicates a globally managed address (e.g., managed by IEEE). When this bit is set to 1, it indicates a locally managed address. The lower 24 bits of the Ethernet address represent locally managed or vendor-assigned codes. This part is typically assigned using 24 zeros for the first NIC, and then sequentially until 24 ones are used for the last NIC (block 16 777216). You will find that many manufacturers use the same 6-digit hexadecimal value as the last six digits of the serial number to indicate that this is the NIC they produced.Binary to Decimal and Hexadecimal ConversionsBefore we get started with the TCP/IP protocol and IP addressing (see Chapter 5 for details), it's important that you really understand the differences between binary, decimal, and hexadecimal values, and how to convert between these formats.Let's start with binary values, which are actually very simple. Numbers in binary use only 1 or 0, and each number is called 1 bit (bit, which is an abbreviation for the previous nary digi/). Usually we count in 4bit or 8bit units, which are called Nibble and Byte accordingly.