Description: The status of a mirror group.  A mirror group will be inactive
when it was created.

The status of a mirror group can be changed automatically from inactive
to active when appropriate conditions were met, also, it can be changed
automatically from active to inactive when these conditions disappeared.

Followings are conditions for a mirror group to become active:
  group type          conditions
  ============================================================================
  local               mirroring-port, monitor-port
  remoteSource        mirroring-port, remote-probe vlan, reflector-port(may not
                      be supported by some products)
  remoteDestination   monitor-port, remote-probe vlan