What is the cause of this error?

One of Cisco Nexus Series interfaces has become errdisabled with the error message “DCX-No ACK in 100 PDUs”. What is the cause of this error?
A. The host has not responded to the Control Sub-TLV DCBX exchanges of the switch.
B. The acknowledgement number in the server response has not incremented for 100 exchanges.
C. Cisco Discovery Protocol is disabled on the switch.
D. LLDP is disabled on the switch.

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0 thoughts on “What is the cause of this error?

  1. Answer is A.

    Data Center Bridging Capability Exchange (DCBX) Type Length Values (TLV) are packaged within a Link Layer Discovery Protocol (LLDP) frame that is exchanged between the switch and the converged network adapter (CNA). One such Control Sub-TLV is used for acknowledgement (ACK), which is sequence-based. For example, the switch sends a Control Sub-TLV with a SeqNo of 1 and an AckNo of 2. The host is supposed to inverse this, and send an LLDP frame with a Control Sub-TLV with a SeqNo of 2 and an AckNo of 1. Refer to the Packet Captures section of this article for more details.

    The switch expects this exchange from the host every 30 seconds. If the switch does not see this exchange for 100 Protocol Data Units (PDUs) , which is 3000 seconds or 50 minutes, the switch disables with this error:

    N5k %ETHPORT-2-IF_DOWN_ERROR_DISABLED: Interface Ethernet115/1/17 is down
    (Error disabled. Reason:DCX-No ACK in 100 PDUs)
    N5k %ETHPORT-2-IF_DOWN_ERROR_DISABLED: Interface Ethernet116/1/16 is down
    (Error disabled. Reason:DCX-No ACK in 100 PDUs)

    https://www.cisco.com/c/en/us/support/docs/switches/nexus-5000-series-switches/116249-troubleshoot-nexus-00.html

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