Hitless Stacking Configuration Notes and Feature Limitations
- Layer 3 multicast traffic is supported by hitless stacking.
- After a switchover or failover, the syslog may contain invalid (non-existent) port numbers in messages such as “Interface portnum state up.” This is because some messages from the old active controller remain in the syslog after a switchover or failover.
- Failover for devices connected to the management port is not supported. For example, if during a failover, an end station is connected to the stack through the management port of the active controller, the connection is shut down. After the failover, the management port on the new active controller will work.
- The following describes hitless stacking limitations with software-based licensing
for BGP:
- To enable BGP on a stack unit, you should have an appropriate BGP license installed on all the stack units.
- If the active controller has a BGP license but any other unit in the stack does not have one, you cannot enable BGP on the stack unit.
- If the active controller is not running BGP, a stack unit is operational regardless of whether the active controller or stack units have a BGP license.
- If the active controller is running BGP and a unit without a BGP license joins the stack, the unit is put into a non-operational state. However, If the user installs a valid BGP license to a non-operational unit, the unit immediately becomes operational. If the user disables BGP instead, the active controller returns the non-operational units to operation.