Configuring LACP Link Protection

Note: When using LACP link protection, you can configure only two member links to an aggregated Ethernet interface: one active and one standby.

To force active and standby links within an aggregated Ethernet, you can configure LACP link protection and system priority at the aggregated Ethernet interface level using the link-protection and system-priority statements. Configuring values at this level results in only the configured interfaces using the defined configuration. LACP interface configuration also enables you to override global (chassis) LACP settings.

LACP link protection also uses port priority. You can configure port priority at the Ethernet interface [gigether-options] hierarchy level using the port-priority statement. If you choose not to configure port priority, LACP link protection uses the default value for port priority (127).

Note: LACP link protection supports per-unit scheduling configuration on aggregated Ethernet interfaces.

Enabling LACP Link Protection

To enable LACP link protection for an aggregated Ethernet interfaces, use the link-protection statement at the [edit interfaces aeX aggregated-ether-options lacp] hierarchy level:

By default, LACP link protection reverts to a higher-priority (lower-numbered) link when that higher-priority link becomes operational or a link is added to the aggregator that is determined to be higher in priority. However, you can suppress link calculation by adding the non-revertive statement to the LACP link protection configuration. In nonrevertive mode, once a link is active and collecting and distributing packets, the subsequent addition of a higher-priority (better) link does not result in a switch and the current link remains active.

If LACP link protection is configured to be nonrevertive at the global ([edit chassis] hierarchy) level, you can add the revertive statement to the LACP link protection configuration to override the nonrevertive setting for the interface. In revertive mode, the addition of a higher-priority link to the aggregator results in LACP performing a priority recalculation and switching from the current active link to the new active link.

Caution: If both ends of an aggregator have LACP link protection enabled, make sure to configure both ends of the aggregator to use the same mode. Mismatching LACP link protection modes can result in lost traffic.

Configuring LACP System Priority

To configure LACP system priority for aggregated Ethernet interfaces on the interface, use the system-priority statement at the [edit interfaces aeX aggregated-ether-options lacp] hierarchy level:

The system priority is a 2-octet binary value that is part of the LACP system ID. The LACP system ID consists of the system priority as the two most-significant octets and the interface MAC address as the six least-significant octets. The system with the numerically lower value for system priority has the higher priority. By default, system priority is 127, with a range of 0 to 65,535.

Configuring LACP Port Priority

To configure LACP port priority for aggregated Ethernet interfaces, use the port-priority statement at the [edit interfaces interface-name gigether-options 802.3ad aeX lacp] or [edit interfaces interface-name fastether-options 802.3ad aeX lacp] hierarchy levels:

The port priority is a 2-octet field that is part of the LACP port ID. The LACP port ID consists of the port priority as the two most-significant octets and the port number as the two least-significant octets. The system with the numerically lower value for port priority has the higher priority. By default, port priority is 127, with a range of 0 to 65,535.

Port aggregation selection is made by each system based on the highest port priority and are assigned by the system with the highest priority. Ports are selected and assigned starting with the highest priority port of the highest priority system and working down in priority from there.

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