This flag controls whether LLDP on a given port is made CDP-aware, meaning it will also recognize and interoperate with Cisco's proprietary CDP discovery protocol on that link rather than only speaking standard LLDP. Administrators enable this on ports connected to Cisco equipment that only speaks CDP, so neighbor-discovery information still gets exchanged despite the protocol mismatch. For example, setting this true on a port uplinked to a Cisco switch would let the local device still learn and report neighbor information even though the Cisco device is using CDP rather than LLDP.