A conceptual row in the nlHostTable.
The hlHostControlIndex value in the index identifies the
hlHostControlEntry on whose behalf this entry was created.
The protocolDirLocalIndex value in the index identifies the
network layer protocol of the nlHostAddress.
An example of the indexing of this entry is
nlHostOutPkts.1.783495.18.4.128.2.6.6.
Note that some combinations of index values may result in an
index that exceeds 128 sub-identifiers in length, which exceeds
the maximum for the SNMP protocol. Implementations should take
care to avoid such combinations.