This variable is valid only for mirroring
transfers. It allows mirroring destinations
to be grouped. A given hpicfBridgeMirrorSessionID
can only be used with 1 destination. However,
multiple sources may be related to the same
hpicfBridgeMirrorSessionID. To ensure that the
hpicfBridgeMirrorSessionID is properly assigned,
it can only be updated when the respective
portCopyEntry object is in the notReady state.
For non-mirroring transfers, the value should
be set to 0.