Description: For devices for which OpenView can do 'smart' network
(i.e, bridges and hubs) submap layout, this indicates
which port this interface corresponds to on the
device, according to following:

    Value               Meaning
    -------     -------------------------------------
    < 255       Corresponds to a single port (the
                value '1' means 'port 1').  This type
                of value is typical for bridges.

    >= 255      Corresponds to a port group where the
                port group number is obtained by
                subracting 255 (the value '257' means
                'port group 2').  This type of value
                is typical for hubs.

Note: The port number OpenView uses will not
necessarily match the vendor port number, but will
start at 1 for the first non-port-group port.  For
example, if a hub has 12 EtherTwist ports, identified
by the vendor as ports 1-12 and belonging to the same
port group, and also an AUI port identified by the
vendor as port 13, the AUI port will be port 1 for
purposes of OpenView.

For non-smart network connector devices, this value
should be 0 and can be ignored.