The Switched Environment: Ethernet Switches, MAC Addresses, and Frame Forwarding

Vocabulary practice flashcards covering switched LAN environments, MAC address notation and structure, switch forwarding logic, CAM tables, and the operational differences between hubs and switches.

Switched Environment

A local area network (LAN) setup where network devices are interconnected using network switches rather than hubs.

Ethernet MAC Address

A 48-bit binary address expressed using 12 hexadecimal digits that uniquely identifies an Ethernet device or network interface.

Organizationally Unique Identifier (OUI)

The first 6 hexadecimal digits (3 bytes or 24 bits) of an Ethernet MAC address that identifies the vendor or manufacturer of the network interface.

Vendor-Assigned Value

The final 6 hexadecimal digits (3 bytes or 24 bits) of an Ethernet MAC address assigned uniquely by the manufacturer to identify a specific device interface.

Hexadecimal Padding

The convention of prepending leading zeroes to hexadecimal values to fill a complete 8-bit (two-digit) representation, such as writing a value of 5 as 05.

Hexadecimal Notation

Common formats used to distinguish hex numbers from decimal numbers, including the prefix 0x (e.g., 0x73), a subscript 16, or a trailing H (e.g., 73H).

Frame Forwarding

The Layer 2 process where an Ethernet switch receives data frames on an ingress port and directs them toward their destination based on Media Access Control (MAC) addresses.

Ingress Port

The specific switch port through which an incoming data frame enters the switch.

Switching Decision Criteria

The two primary criteria an Ethernet switch uses to forward traffic: the ingress port and the destination MAC address.

MAC Address Table

A dynamic table maintained by a switch that records each connected device's MAC address and maps it to the specific switch port to which it is attached.

Content Addressable Memory (CAM) Table

A specialized high-speed searching memory used in switches to store and quickly execute port-to-MAC address lookups.

Flooding

The action of a switch forwarding a received frame out of all ports except the ingress port, occurring when the destination MAC address is unknown in the MAC table or is a broadcast address.

Aging Timer

A countdown timer on a switch that maintains a MAC address entry for a set duration (typically five minutes) before deleting it if no frames from that source address are detected.

Hub

A passive networking device operating at the physical layer that connects multiple PCs in a LAN, transmitting electrical signals across half-duplex links without traffic reduction or path selection capabilities.

Switch

An active networking device operating at the data link layer (Layer 2) that directs frames and packets out dedicated ports using integrated circuits, software, and full-duplex communication.

Virtual Local Area Network (VLAN)

A feature supported by switches that enables the logical segmentation of switch ports and helps reduce the number of broadcast domains.