PAUSE frames are Ethernet MAC control frames that allow devices on a full-duplex link to request a pause in frame transmission. They carry a PAUSE opcode and pause time parameter, specifying the length of the requested pause in units of 512 bit times. PAUSE frames are sent to a reserved multicast address to simplify flow control without requiring knowledge of the destination's individual address. Switches will not forward frames sent to this multicast address but will process them internally for flow control purposes.