With IPHost Network Monitor you can run simple snmp requests against a IBM device in your network.
ipv6IfStatsOutDiscards
ipv6 If Stats Out Discards
1.3.6.1.2.1.55.1.6.1.12
The number of output IPv6 datagrams for which no problem was encountered to prevent their transmission to their destination, but which were discarded (e.g., for lack of buffer space). Note that this counter would include datagrams counted in ipv6IfStatsOutForwDatagrams if any such packets met this (discretionary) discard criterion.
Back to ibm-ipv6 MIB page.
IPHost Network monitor allows you to monitor ipv6IfStatsOutDiscards on IBM device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring IBM Flex systems right now.