A reference to MIB definitions specific to the
particular routing protocol which is responsible
for this route, as determined by the value
specified in the route's wfIpForwardProto value.
If this information is not present, its value
should be set to the OBJECT IDENTIFIER { 0 0 },
which is a syntactically valid object identifier,
and any implementation conforming to ASN.1
and the Basic Encoding Rules must be able to
generate and recognize this value.