What is a MAC Address and why is it important to me?

Layer 2 is also known as the data link layer. It is the second layer of OSI model. This layer transfers data between adjacent network nodes in a WAN (Wide area network, ISP or large corporate network) or between nodes on the same LAN (Local area network) segment. It is a way to transfer data between network entities and detect or correct errors happened in the physical layer. Layer 2 switching uses the local and permanent MAC (Media Access Control) address to send data around a local area on a switch.

Layer 2 addressing Media Access Control Addresses (or MAC Address) are a 48-Bit identifier for every piece of hardware we have in existence today. This is how devices differentiate themselves on the ethernet plane or better known as Layer 2 of the OSI/ISO model.

There are 2^48 (or 281,474,976,710,656) possible MAC addresses. MAC addresses identify many things, such as the type of device being used. A MAC address is used by the network to send and receive data (computer information) to the right place almost like mail being sent and received from a home mail address.

The first 3 Octet of a MAC Address are the Organizationally Unique Identifier or the "Manufacturer of the Product" and the last 3 Octet are the Network Interface Controller or NIC which are specific to the device they are given too. Each OUI has about 16 million devices they can assign NIC specific MAC Addresses to. 2^24 is 16,777,216 devices with unique address. If you've ever seen a switch each port on that switch has a unique MAC Address which is called a burn in address.. So a 48 port switch takes up 48 MAC Address from its manufacturers NIC Identification pool.

There can be 16,777,216 unique manufacturers around the globe with this current model. Some manufacturers already have so many devices in service that they have multiple OUI's I will cite Cisco a manufacturer of computer networking appliances as being one of them.

The following network technologies use the EUI-48 identifier format:

• IEEE 802 networks
• Ethernet
• 802.11 wireless networks (Wi-Fi)
• Bluetooth
• IEEE 802.5 Token Ring
• Fiber Distributed Data Interface (FDDI)
• Asynchronous Transfer Mode (ATM), switched virtual connections only, as part of an NSAP address
• Fibre Channel and Serial Attached SCSI (as part of a World Wide Name)
• The ITU-T G.hn standard, which provides a way to create a high-speed (up to 1 gigabit/s) local area network using existing home wiring (power lines, phone lines and coaxial cables). The G.hn Application Protocol Convergence (APC) layer accepts Ethernet frames that use the EUI-48 format and encapsulates them into G.hn Medium Access Control Service Data Units (MSDUs).

Every device that connects to an IEEE 802 network (such as Ethernet and WiFi) has an EUI-48 address. Common networked consumer devices such as PCs, smartphones and tablet computers use EUI-48 addresses.

More on this in the link below.

https://lnkd.in/diCq5kF

Also we have the EUI-64, 64-Bit addresses.

There are 2^64 address in this space 18,446,744,073,709,551,616 or 18 quintillion addresses.

EUI-64 (Extended Unique Identifier) is a method we can use to automatically configure IPv6 host addresses. An IPv6 device will use the MAC address of its interface to generate a unique 64-bit interface ID. However, a MAC address is 48 bit and the interface ID is 64 bit.

Here is a conversion table to get from 48-bit M.A.C. Addresses to 64-bit IPv6 Modified EUI-64 interface identifiers.

We add 2 more 8 bit Octets in the middle of our 48-Bit IEEE 802 MAC Address.

EUI-64 identifiers are used in:

• IEEE 1394 (FireWire)
• InfiniBand
• IPv6 (Modified EUI-64 as the least-significant 64 bits of a unicast network address or link-local address when stateless address autoconfiguration is used.)[13] IPv6 uses a modified EUI-64, treats MAC-48 as EUI-48 instead (as it is chosen from the same address pool) and inverts the local bit.[b] This results in extending MAC addresses (such as IEEE 802 MAC address) to modified EUI-64 using only FF-FE (and never FF-FF) and with the local bit inverted.[14]
• ZigBee / 802.15.4 / 6LoWPAN wireless personal-area networks
• IEEE 11073-20601 (IEEE 11073-20601 compliant medical devices)[15]

More on this below

https://lnkd.in/dYmJc4p

If you want to read more about Layer 2 switching I suggest checking out

https://embeddedgeeks.com/layer-2-switching/

or

https://en.wikipedia.org/wiki/Network_switch