Because the agent-addr field in an SNMPv1 trap message can represent only IPv4 (32-bit) addresses, the SNMP agent on an IPv6 device will set the agent-addr field in a generated v1 trap to the null IP address 0.0.0.0.
Similarly, because the standard trap-forwarding MIBs can represent only IPv4 addresses, any trap forwarder that processes a v2c or v3 trap that is received from an IPv6 device will set the standard snmpTrapAddress.0 varbind to the null IP address 0.0.0.0.
In either case, the traditional trap forwarder will discard the trap because the source device address is not preserved in the forwarded trap. Forwarding such a trap would be futile because the target trap receiver would not be able to determine the source device address of the trap.
Until a Request For Comment (RFC) is drafted and accepted for updating the standard MIBs to be able to represent both IPv4 (32-bit) and IPv6 (128-bit) addresses, VMware, Inc. will employ two new private MIB objects that are IP-version independent to represent IPv4 and IPv6 addresses in forwarded traps.
Any trap receiver that is able to read and understand the new private MIB objects is able to decipher forwarded traps that contain a source IPv6 address. Only the IP Availability Manager’s built-in trap receiver and the SNMP Trap Adapter will have this capability. All other products discard any forwarded trap that contain a source IPv6 address.
The private MIB is defined in the SMARTS-MIB.my file located in the BASEDIR/smarts/conf/notifier directory in both the IP Manager installation area and the Service Assurance Manager installation area. Definitions of the two new IP-version-independent MIB objects, which are named smSnmpTrapInetAddressType and smSnmpTrapInetAddress, as well as definitions of other new, supporting MIB objects have been added to this file.
