23.3.2 Port detachment restriction function

The port detachment restriction functionality suppresses the functionality that detaches a faulty port so that link aggregation with the rest of the ports can continue if a link fault occurs. If the port detachment restriction functionality is used and a fault occurs on any port in a channel group, operation of the entire channel group stops on the assumption that a group-wide fault has occurred. If no ports in the channel group are faulty, then operation of the channel group is restarted.

By using this function in conjunction with redundancy features such as uplink redundancy, routes can be switched on a group-by-group basis even if only one port fails in the channel group.

This functionality is available only when LACP link aggregation is used.

The port detachment restriction functionality permits the channel groups of connected devices to perform link aggregation between them if the device with the higher priority judges that all ports in both channel groups are usable for aggregation. Because this functionality never permits link aggregation when any ports are detached, the intended bandwidth is guaranteed.

Priority is determined first by LACP system priority set in the configuration, and then by MAC addressof the channel group. That is, if LACP system-priorities are the same, MAC addressof the channel group is used.

The devices that determine whether all ports in a channel group can be aggregated are listed in the following order in order of selection priority:

1. LACP system priority

   Devices with lower LACP system-priority values take precedence.

2. MAC address of the channel group

   Devices with lower MAC addresses take precedence.