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[NFX150] Chassis cluster flaps if fxp0 interface is not plugged in

  [KB34759] Show Article Properties


Chassis clusters are supported on NFX150 beginning with Junos OS release 19.1R1. However, many customer environments do not have the IP network scheme to use an OOB port, and therefore cannot make use of the fxp0 interface.

This article gives the reason for the chassis cluster to flap if fxp0 is not plugged in on NFX150 devices and suggests that disabling this interface would resolve the issue.

  • Chassis cluster bounces and the device is unstable after enabling the chassis cluster.

  • The fxp0 interface is not plugged in.

  • The following alarm messages are seen with no fxp0 interface connected:

    • FPC Management0 Ethernet Link Down

    • Host 0 fxp0 : Ethernet Link Down


When the fxp0 interface is not connected, the system will determine that the FPC Management0 link is down. A new feature was introduced in Junos OS 18.4 that included a health monitoring check in a chassis cluster configuration. If the health monitoring check is not enabled, this feature could cause the node to reboot on its own.


In order to prevent the chassis from bouncing when fxp0 is not connected, in a chassis cluster environment, configure fxp0 to be disabled as shown below:

set interfaces fxp0 disable

This will prevent rolling reboots when the chassis cluster is enabled and there is no fxp0 interface link up.

If you have the fxp0 interface configured in a group, then you could do the following:

set groups node0 interface fxp0 disable
set groups node1 interface fxp0 disable
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