Explanation
The Data Center Bridging Exchange Protocol (DCBXP) is an extension of LLDP. It is used to announce, exchange, and negotiate node parameters between peers. DCBXP parameters are packaged into a specific DCBXP TLV. This TLV is designed to provide an acknowledgement to the received LLDP packet. DCBXP is enabled by default, provided LLDP is enabled. DCBXP is disabled on ports where LLDP transmit or receive is disabled.
https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5000/sw/layer2/503_n2_1/b_Cisco_n5k_layer2