Interface hold timers

You can configure hold timers that keep an interface operationally enabled or disabled for a specified amount of time following an event that brings the interface up or shuts the interface down.

For example, you can configure a hold timer that keeps an interface operationally disabled for a period of time following a system reboot, and you can configure a hold timer that keeps an interface operationally enabled for a period of time after the interface goes down.

The main use for hold timers is to reduce the number of link transitions and advertise/withdraw messages in networks where there are flapping optics.

You can configure a hold-time up timer and a hold-time down timer for an interface:

• hold-time up timer

  This timer specifies the amount of time an interface is kept operationally disabled following an event that normally enables it, such as entering the interface admin-state enable command or a system reboot.

  The interface remains disabled from the time the event occurs until the hold-time up timer expires. While the hold-time up timer is running, the transceiver is enabled but the system does not consider the interface operationally up until the timer expires.

• hold-time down timer

  This timer specifies the amount of time an interface remains operationally enabled following an event that brings the interface down. When triggered, the hold-time down timer keeps the interface operationally enabled until the timer expires. Entering the interface admin-state disable command does not trigger the hold-time down timer, nor does internal events such as fabric unavailability.

  If you manually disable the interface while the hold-time down timer is running, the interface is disabled immediately, and the timer is aborted.

The hold timers can be set to a value from 100 to 86 400 000 ms in a multiple of 50 ms. The default value is 0, which indicates that no hold time is considered when an interface changes state.

The hold timers are available for Ethernet interfaces only, including those that are part of a LAG. You cannot configure a hold timer for an interface in breakout mode.

The hold timer does not affect the port LED color, which reflects the physical status of the port; that is, the port LED is green when the hold-time up timer is running, and solid amber when the hold-time down timer is running.

--{ candidate shared default }--[  ]--
# info interface ethernet-1/1 ethernet
    interface ethernet-1/1 {
        ethernet {
            hold-time {
                up 200000
                down 100000
            }
        }
    }

--{ running }--[  ]--
# info from state interface ethernet-1/1 ethernet hold-time
    interface ethernet-1/1 {
        ethernet {
            hold-time {
                up 200000
                down 100000
                up-expires "2024-01-12T23:57:28.647Z (85 seconds from now)"
            }
        }
    }