Active/standby LAG is used to provide redundancy while keeping consistency of QOS enforcement. Some devices do not support LACP and therefore an alternative solution is required.
The active/standby decision for LAG member links is local decision driven by preconfigured selection-criteria. This decision was communicated to remote system using LACP signaling.
As an alternative, the operator can disable the signal transmitted by using the power-off option for standby-signaling in the CLI command at the LAG level at the port member level. The transmit laser is switched off for all LAG members in standby mode. On switch over (active-links failed), the laser is switched on and all LAG members become active.
This mode of operation cannot detect physical failures on the standby link, which means that the network operator cannot be certain that the standby links are capable to take over in case of active-links failure. This is an inherent limitation of this operational mode.
When LACP goes down on a standby link, a warning message announcing that LACP has expired on the corresponding member port is printed in log 99 at the other end.
The operation where standby ports are powered down is mutually exclusive with LACP and, therefore, is modeled as a separate mode of LACP operation of power-off. For this mode, the best-port selection criteria can be used. This criteria ensures that a subgroup with the best-port (the highest priority port) is always chosen to be used as the active subgroup.
It is not possible to have an active LACP in the power-off mode before the correct selection criteria is selected.