This object identifies the filter group
containing information about source IP
addresses and masks that need to be matched
for this filter. This value must match an entry
in cfgFilterGroupTable whose cfgFilterGroupType
value is set to 'network' and must match an entry
in cfgFilterNetworkGroupTable.
This object cannot be set if any of the following
objects are set:
cippfIpFilterSrcAddress
cippfIpFilterSrcMask.
This object is not instantiated if not applicable.