Hold-down timers control how quickly a LAG responds to operational port state changes. The following timers are supported:
port-level hold-time (up/down) timer
This timer controls the delay before a port is added to or removed from a LAG when the port comes up or goes down. Each port in the LAG has the same timer value, which is configured on the primary LAG link (port). The timer is set with the config>port>ethernet>hold-time command.
subgroup-level hold-down timer
This timer controls the delay before a switch from the current subgroup to a new candidate subgroup, selected by the LAG subgroup selection algorithm. The timer is set with the config>lag>selection-criteria command.
The timer can be configured to never expire, which prevents a switch from an operationally up subgroup to a new candidate subgroup. This setting can be manually overridden by using the tools>perform>force>lag-id command (refer to the 7705 SAR OAM and Diagnostics Guide, ‟Tools Command Reference”, for information on this command).
If the port-level timer is set, it must expire before the subgroup selection occurs and this timer is started. The subgroup-level timer is supported only for LAGs running LACP.
LAG-level hold-down timer
This timer controls the delay before a LAG is declared operationally down when the available links fall below the required port or bandwidth minimum. This timer is recommended for MC-LAG operation. The timer prevents a LAG from being brought down when an MC-LAG switchover executes a make-before-break switch. The LAG-level timer is set with the config>lag>hold-time down command.
If the port-level timer is set, it must expire before the LAG operational status is processed and this timer is started.