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 would normally enable 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 1-86,400 seconds. There is no default value; if not configured, 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 200
                down 100
            }
        }
    }

--{ running }--[  ]--
# info from state interface ethernet-1/1 ethernet hold-time
    interface ethernet-1/1 {
        ethernet {
            hold-time {
                up 200
                down 100
                up-expires 85 seconds from now
            }
        }
    }