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Cisco Cluster Network Switch is in a reboot loop

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Category:
ontap-9
Specialty:
HW
Last Updated:

Applies to

  • FAS/AFF
  • ONTAP 9

Issue

  • Cluster ports connecting to the switch from both nodes go down at the same time.

    EMS 

    [node1: kernel: netif.linkDown:info]: Ethernet e0a: Link down, check cable.
    [node2: kernel: netif.linkDown:info]: Ethernet e0a: Link down, check cable.
    Sysconfig -a 

        NetApp Release 9.15.1P14: Tue Aug  5 11:53:54 EDT 2025
         System ID: 05XXXXX994 (node1); partner ID: 05XXXXX944 (node2)
         System Serial Number: 95XXXXXX2341 (node1)

        slot 0: Dual 10/25G Ethernet Controller E823L-SFP+
          e0b MAC Address:    d0:39:ea:c8:2a:36 (auto-25g_cr-fd-up)
              SFP Vendor:         CISCO-BIZLINK
              SFP Part Number:    L45593-D278-D20
              SFP Serial Number:  LCC2813GWAA-CH1
          e0a MAC Address:    d0:39:ea:c8:2a:37 (auto-unknown-fd-down)
              SFP Vendor:         CISCO-BIZLINK
              SFP Part Number:    L45593-D278-D20
              SFP Serial Number:  LCC2813GWAP-CH1

        NetApp Release 9.15.1P14: Tue Aug  5 11:53:54 EDT 2025
         System ID: 05XXXXX944 (node2); partner ID: 05XXXXX994 (node1)
         System Serial Number: 95XXXXXX2374 (node2)
         System Rev: A9

        slot 0: Dual 10/25G Ethernet Controller E823L-SFP+
          e0b MAC Address:    d0:39:ea:c8:26:bd (auto-25g_cr-fd-up)
              SFP Vendor:         CISCO-BIZLINK
              SFP Part Number:    L45593-D278-D20
              SFP Serial Number:  LCC2813GWAA-CH2
          e0a MAC Address:    d0:39:ea:c8:26:be (auto-unknown-fd-down)
              SFP Vendor:         CISCO-BIZLINK
              SFP Part Number:    L45593-D278-D20
              SFP Serial Number:  LCC2813GWAP-CH2
  • Cluster reports following health alerts: 
    Cluster1::> system health alert show
                   Node: node2
               Alert ID: ClusterSwitchConnectionDegraded_Alert
               Resource: node1
               Severity: Major
        Indication Time: Sat Jan 03 14:39:23 2026
               Suppress: false
            Acknowledge: false
         Probable Cause: Only one cluster switch, "switch2(FDXXXXXX3H)",
                         has been discovered to be connected to the cluster
                         ports of node "node1". If a cluster
                         connection was not discovered, but the expected
                         cluster switch is listed in the output of "system
                         switch ethernet show", it indicates that the node is
                         not currently receiving discovery information about
                         the missing switches.
        Possible Effect: If the remaining cluster switch,
                         "switch2(FDXXXXXX3H)", that is connected to
                         node "node1" fails, the node may lose access
                         to the cluster.
    Corrective Actions: 1) Ensure node "node1" is connected to multiple cluster switches. Inspect cables for damage or loose connections, check port status and health, verify VLAN configurations, ensure matching port speed and duplex settings, and review logs for errors.
                         2) Enable the corresponding link layer discovery protocol on the affected switch(es) if previously disabled. As a reminder for cluster switches, Broadcom switches use ISDP, Cisco switches use CDP, and Nvidia switches use LLDP. The discovery protocol should be enabled once configured with the correct Reference Configuration File (RCF).
                         Refer to your switch documentation for specific
                         instructions on enabling the protocol manually.

                   Node: node2
               Alert ID: SwitchIslIfDownWarn_Alert
               Resource: Ethernet1/35
               Severity: Major
        Indication Time: Sat Jan 03 13:42:39 2026
               Suppress: false
            Acknowledge: false
         Probable Cause: The cable attached to the ISL port
                         "switch2(FDXXXXXX3H)/Ethernet1/35" with the
                         description of "Intra-Cluster Switch ISL Port 1/35
                         (port channel)" might be faulty. For the port-channel,
                         please check each individual link.
        Possible Effect: Inter- or Intra- cluster redundancy might be lost.
    Corrective Actions: 1) Check whether the cable is fully inserted into the interface port on both ends.
                         2) Reconnect the ISL port using another cable. After
                         reconnecting it, verify whether the link of the ISL
                         port is up by executing the commands per the switch
                         configuration guide or by checking whether the Link
                         status LED is on.

                   Node: node2
               Alert ID: SwitchIslIfDownWarn_Alert
               Resource: Ethernet1/36
               Severity: Major
        Indication Time: Sat Jan 03 13:42:39 2026
               Suppress: false
            Acknowledge: false
         Probable Cause: The cable attached to the ISL port
                         "switch2(FDXXXXXX3H)/Ethernet1/36" with the
                         description of "Intra-Cluster Switch ISL Port 1/36
                         (port channel)" might be faulty. For the port-channel,
                         please check each individual link.
        Possible Effect: Inter- or Intra- cluster redundancy might be lost.
    Corrective Actions: 1) Check whether the cable is fully inserted into the interface port on both ends.
                         2) Reconnect the ISL port using another cable. After
                         reconnecting it, verify whether the link of the ISL
                         port is up by executing the commands per the switch
                         configuration guide or by checking whether the Link
                         status LED is on.
  • Unable to fetch switch logs as the switch is rebooting every 3 to 4 minutes.

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