Dvmrp circuit list. This is a list of DVMRP
circuits. If a circuit appears in this list, the filter
applies to DVMRP advertisements sent via that circuit.
If non-null, The octet string contains one or more 2-octet
circuit number. If the first 2-octet contains all f, this
filter does not applies to any circuits. If null, this
filter applies to any outbound
DVMRP circuit.