MACsec (Media Access Control Security) is a security technology that provides secure communication for all traffic on Ethernet links. MACsec provides Layer 2 hop-by-hop encryption, which enables data confidentiality and integrity to be maintained between nodes in the network. It operates at Layer 2 of the OSI model and encrypts packets before they are transmitted across the network cables and devices. References: Implementing and Operating Cisco Service Provider Network Core Technologies