Hi,
Which version of OCI are we talking about? The brocade SNMP data source phased out with 7.1 or so (may have been 7.0).
That isn't to say we're not using SNMP today, but we do that for performance acquisition exclusively. Inventory today is SSH.
In any case, when it comes to SNMPv3, you want to make sure that:
1. If there are any ACL's configured on the switches, the OCI server is included. You can check on the switch with the command "snmpconfig --show accesscontrol"
2. An existing user is assigned to one of the 6 SNMP slots. You can check with the commany "snmpconfig --show snmpv3". Please note that "snmpuser{1,2,3} and snmpadmin{1,2,3} are default entries and are not really usable out of the box. You want to configure this explicitly for an existing user by running "snmpconfig --set snmpv3". The use of an auth protocol and/or priv protocol is optional. My personal preference is to use SHA for auth and nothing for priv (which is for encrypting the data). If you choose to use a privacy protocol, I'd recommend AES since it uses more advanced cyphers than DES/3DES. Whatever you configure on the switches side though, the data source configuration in OCI need to match that: username/password and the authentication and privacy protocols in use.
3. If there is a firewall in between the OCI server and the switches, port 161/UDP can go through unidirectional from OCI => Switch.
I think I covered everything. I hope this helps.