Ethernet is a wired technology used to connect computers and devices into a local area network (LAN). It uses physical cables—such as copper wires or fiber optics—to send data safely and quickly between machines without using Wi-Fi.
etm: named after the historical, disproven physics concept of the luminiferous aether since its inventor envisioned the network cable as a pervasive, passive medium that carried data signals to every connected device.
An Ethernet frame is a data container used to transmit information across a local area network. A standard Ethernet II frame consists of a Destination MAC (6 bytes), Source MAC (6 bytes), EtherType (2 bytes), Payload/Data (46–1500 bytes), and a Frame Check Sequence (FCS) trailer (4 bytes).
E.g., suppose Device A wants to talk to Device B on the same LAN, it uses ARP (Address Resolution Protocol):
Device A knows B’s IP address, but needs its MAC address to build the Ethernet frame.
Device A sends an ARP Request to the broadcast MAC (FF:FF:FF:FF:FF:FF).
Device B responds with its specific MAC address.
Switches store these in a MAC Address Table to route frames directly to the correct physical port.
An Ethernet frame is a digital data packet used in local area networks (LANs), acting as a container wrapping around the actual data, adding routing addresses and error-checking info fopr data to move safely from a device to another.
An Ethernet frame is built as raw net data can't be dumped onto a physical wire/Wifi signal as a continuous data stream. Without frames, receiving hardware can't know where a message starts, ends, who sent it, or whether the data got corrupted during transmission.
Main reasons an Ethernet frame:
Addressing (where it goes): The frame attaches the source and destination MAC addresses (Layer 2), allowing switches to read the header and route the data directly to the correct device on the local network rather than flooding every device.
Synchronization and boundaries: The frame adds a Preamble and Start Frame Delimiter (SFD) at the start, followed by a fixed structure. This notifies the network interface card (NIC) that data is arriving and lets it align its clock to read the incoming bits accurately.
Error detection (being damaged or not): Every Ethernet frame ends with a Frame Check Sequence (FCS) containing a Cyclic Redundancy Check (CRC) hash. If electrical noise/signal loss flips a bit in transit, the receiver's calculation won't match, and the corrupted frame is immediately dropped.
Protocol Identification (internal content): The frame includes an EtherType field (e.g., 0x0800 for IPv4, 0x0806 for ARP). This tells the receiving device's operating system which upper-layer protocol (Layer 3) should process the payload.
Traffic control and fairness: Framing caps data into manageable chunks (typically up to 1500 bytes of payload), stopping 1 large file transfer from hogging the physical media and starving other network devices.