Stateful Failover (Mirroring)

Stateful failover allows a backup platform to take over when a primary platform fails, without dropping existing sessions or breaking persistency. Stateful failover is provided by mirroring the content of the tables that define a session.

There are 3 Mirroring procedures that you can perform:

Active Platform (Device) Mirroring

Backup Platform (Device) Mirroring

Mirroring Platform (Device) Parameters

For effective and reliable mirroring you need to:

Provide a direct connection between the two platforms.

Configure an IP interface on each platform for the direct connection port and address used as the Mirroring Device Address for the other platform.

Exclude physical port used for inter-platform communication from Interface grouping.

Notes:  

Optionally you can also use a trunk (link aggregation) for direct connection between two platforms.

Mirroring is not supported when delayed binding is used with Layer 7 Persistent Switching Mode and configured to either overwrite or maintain.

Mirroring is not supported in conjunction with a farm that is configured for Layer 7 modification.

Mirroring is supported for the Layer 7 Persistent Switching Mode named first.

Client entries that are not mirrored are RADIUS client entries.

Mirroring can handle long and short sessions and support HTTP traffic. The following are mirrored:

Dynamic Session ID Table

DNS Persistency Table (AppDirector Global Only)

Proximity table