DVMRP gateway list. This octet string contains the addresses
of one or more routers that could send DVMRP updates to this
router. If a router address is included in this list,
this filter applies to DVMRP advertisements from that router.
If non-null, The octet string contains one or more 4-octet
IP addresses. If null, this filter applies to DVMRP updates
from any router.