What is OSI Layer 2?

Understanding OSI Layer 2

Data-link layer. Layer 2 of the OSI model handles reliable node-to-node data transfer across a physical link. It packages raw bits from the physical layer into data frames manages physical addressing MAC addresses controls access to the physical medium and performs error detection. Security at this layer addresses issues like MAC spoofing and ARP poisoning. Data-link layer security is addressed in standards like IEEE 802.1X ISO 27001 and NIST SP 800-53. Organizations implement Layer 2 security through switch port security MAC filtering VLAN segmentation ARP inspection and IEEE 802.1X authentication. For example a corporate network might implement port security on all access switches to limit the MAC addresses allowed on each port configure dynamic ARP inspection to prevent ARP spoofing attacks and deploy 802.1X to authenticate devices before they gain network access. Related terms MAC address Ethernet Frame Switches VLAN ARP 802.1X Port security.