MACsec: Chassis cluster (HA) link encryption

Media Access Control Security (MACsec) is supported on control and fabric ports in chassis cluster mode. MACsec is an industry-standard security technology that provides secure communication for all traffic on Ethernet links. MACsec provides point-to-point security on Ethernet links between directly connected nodes and is capable of identifying and preventing most security threats, including denial of service, intrusion, man-in-the-middle, masquerading, passive wiretapping, and playback attacks. For devices in chassis cluster mode, static secure association key (SAK) and connectivity association key (CAK) are used to secure the control and fabric links.