SNS HA clusters and LACP

This section does not explain how to configure a HA cluster.

Calculating the HA quality factor with LACP

You may recall that the quality factor is a mathematical formula that depends on the status (and sometimes the weight) of active interfaces, calculated on both nodes of the cluster in order to nominate the active node.

When the presence of an aggregate is detected, the calculation will be based on the status of the aggregated interface instead of the member interfaces of the aggregate so that the loss of a single interface in the aggregate would not change the quality factor.

Example

The SN2000 appliance used earlier has 10 active Ethernet interfaces of equal weight by default.

All of the interfaces have a working link.

An aggregate lagg0 contains two aggregated interfaces: 8 single interfaces and an aggregate, i.e., 9 interfaces.

The default weight is 100.

With this configuration, the quality factor will be calculated as follows:

(9x100 / 9x100)x100 = 100%

If either of the aggregated interfaces loses its connection, the quality factor will remain the same as it remains in the aggregate of an active interface.

If the aggregate loses its connection, the quality factor will change as follows:

(8x100 / 9x100)x100 = 89%.

  NOTE

Even in SSH, this behavior cannot be modified.