Very Computer

Hi!
I have some touble about oracle's snmp as following:
1.Network snmp commuity is public but oracle is tcp.world.They must be same?
2.Which port snmp use 161,162 or 1161,1162?
3.I have been setup unix snmp because It have snmpd and
master_peer(encap_peer).
   The lsnrctl also have dbsnmp_start that it say  runing.But I use MG-SOFT
mib browser can't see any oracle agent info.